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| <h1 class="top" id="Bash-Features-1"><span>Bash Features<a class="copiable-link" href="#Bash-Features-1"> ¶</a></span></h1> |
| |
| <p>This text is a brief description of the features that are present in |
| the Bash shell (version 5.2, 19 September 2022). |
| The Bash home page is <a class="url" href="http://www.gnu.org/software/bash/">http://www.gnu.org/software/bash/</a>. |
| </p> |
| <p>This is Edition 5.2, last updated 19 September 2022, |
| of <cite class="cite">The GNU Bash Reference Manual</cite>, |
| for <code class="code">Bash</code>, Version 5.2. |
| </p> |
| <p>Bash contains features that appear in other popular shells, and some |
| features that only appear in Bash. Some of the shells that Bash has |
| borrowed concepts from are the Bourne Shell (<samp class="file">sh</samp>), the Korn Shell |
| (<samp class="file">ksh</samp>), and the C-shell (<samp class="file">csh</samp> and its successor, |
| <samp class="file">tcsh</samp>). The following menu breaks the features up into |
| categories, noting which features were inspired by other shells and |
| which are specific to Bash. |
| </p> |
| <p>This manual is meant as a brief introduction to features found in |
| Bash. The Bash manual page should be used as the definitive |
| reference on shell behavior. |
| </p> |
| |
| <div class="element-contents" id="SEC_Contents"> |
| <h2 class="contents-heading">Table of Contents</h2> |
| |
| <div class="contents"> |
| |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Introduction-1" href="#Introduction">1 Introduction</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-What-is-Bash_003f-1" href="#What-is-Bash_003f">1.1 What is Bash?</a></li> |
| <li><a id="toc-What-is-a-shell_003f-1" href="#What-is-a-shell_003f">1.2 What is a shell?</a></li> |
| </ul></li> |
| <li><a id="toc-Definitions-1" href="#Definitions">2 Definitions</a></li> |
| <li><a id="toc-Basic-Shell-Features-1" href="#Basic-Shell-Features">3 Basic Shell Features</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Shell-Syntax-1" href="#Shell-Syntax">3.1 Shell Syntax</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Shell-Operation-1" href="#Shell-Operation">3.1.1 Shell Operation</a></li> |
| <li><a id="toc-Quoting-1" href="#Quoting">3.1.2 Quoting</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Escape-Character-1" href="#Escape-Character">3.1.2.1 Escape Character</a></li> |
| <li><a id="toc-Single-Quotes-1" href="#Single-Quotes">3.1.2.2 Single Quotes</a></li> |
| <li><a id="toc-Double-Quotes-1" href="#Double-Quotes">3.1.2.3 Double Quotes</a></li> |
| <li><a id="toc-ANSI_002dC-Quoting-1" href="#ANSI_002dC-Quoting">3.1.2.4 ANSI-C Quoting</a></li> |
| <li><a id="toc-Locale_002dSpecific-Translation" href="#Locale-Translation">3.1.2.5 Locale-Specific Translation</a></li> |
| </ul></li> |
| <li><a id="toc-Comments-1" href="#Comments">3.1.3 Comments</a></li> |
| </ul></li> |
| <li><a id="toc-Shell-Commands-1" href="#Shell-Commands">3.2 Shell Commands</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Reserved-Words-1" href="#Reserved-Words">3.2.1 Reserved Words</a></li> |
| <li><a id="toc-Simple-Commands-1" href="#Simple-Commands">3.2.2 Simple Commands</a></li> |
| <li><a id="toc-Pipelines-1" href="#Pipelines">3.2.3 Pipelines</a></li> |
| <li><a id="toc-Lists-of-Commands" href="#Lists">3.2.4 Lists of Commands</a></li> |
| <li><a id="toc-Compound-Commands-1" href="#Compound-Commands">3.2.5 Compound Commands</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Looping-Constructs-1" href="#Looping-Constructs">3.2.5.1 Looping Constructs</a></li> |
| <li><a id="toc-Conditional-Constructs-1" href="#Conditional-Constructs">3.2.5.2 Conditional Constructs</a></li> |
| <li><a id="toc-Grouping-Commands" href="#Command-Grouping">3.2.5.3 Grouping Commands</a></li> |
| </ul></li> |
| <li><a id="toc-Coprocesses-1" href="#Coprocesses">3.2.6 Coprocesses</a></li> |
| <li><a id="toc-GNU-Parallel-1" href="#GNU-Parallel">3.2.7 GNU Parallel</a></li> |
| </ul></li> |
| <li><a id="toc-Shell-Functions-1" href="#Shell-Functions">3.3 Shell Functions</a></li> |
| <li><a id="toc-Shell-Parameters-1" href="#Shell-Parameters">3.4 Shell Parameters</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Positional-Parameters-1" href="#Positional-Parameters">3.4.1 Positional Parameters</a></li> |
| <li><a id="toc-Special-Parameters-1" href="#Special-Parameters">3.4.2 Special Parameters</a></li> |
| </ul></li> |
| <li><a id="toc-Shell-Expansions-1" href="#Shell-Expansions">3.5 Shell Expansions</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Brace-Expansion-1" href="#Brace-Expansion">3.5.1 Brace Expansion</a></li> |
| <li><a id="toc-Tilde-Expansion-1" href="#Tilde-Expansion">3.5.2 Tilde Expansion</a></li> |
| <li><a id="toc-Shell-Parameter-Expansion-1" href="#Shell-Parameter-Expansion">3.5.3 Shell Parameter Expansion</a></li> |
| <li><a id="toc-Command-Substitution-1" href="#Command-Substitution">3.5.4 Command Substitution</a></li> |
| <li><a id="toc-Arithmetic-Expansion-1" href="#Arithmetic-Expansion">3.5.5 Arithmetic Expansion</a></li> |
| <li><a id="toc-Process-Substitution-1" href="#Process-Substitution">3.5.6 Process Substitution</a></li> |
| <li><a id="toc-Word-Splitting-1" href="#Word-Splitting">3.5.7 Word Splitting</a></li> |
| <li><a id="toc-Filename-Expansion-1" href="#Filename-Expansion">3.5.8 Filename Expansion</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Pattern-Matching-1" href="#Pattern-Matching">3.5.8.1 Pattern Matching</a></li> |
| </ul></li> |
| <li><a id="toc-Quote-Removal-1" href="#Quote-Removal">3.5.9 Quote Removal</a></li> |
| </ul></li> |
| <li><a id="toc-Redirections-1" href="#Redirections">3.6 Redirections</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Redirecting-Input" href="#Redirecting-Input">3.6.1 Redirecting Input</a></li> |
| <li><a id="toc-Redirecting-Output" href="#Redirecting-Output">3.6.2 Redirecting Output</a></li> |
| <li><a id="toc-Appending-Redirected-Output" href="#Appending-Redirected-Output">3.6.3 Appending Redirected Output</a></li> |
| <li><a id="toc-Redirecting-Standard-Output-and-Standard-Error" href="#Redirecting-Standard-Output-and-Standard-Error">3.6.4 Redirecting Standard Output and Standard Error</a></li> |
| <li><a id="toc-Appending-Standard-Output-and-Standard-Error" href="#Appending-Standard-Output-and-Standard-Error">3.6.5 Appending Standard Output and Standard Error</a></li> |
| <li><a id="toc-Here-Documents" href="#Here-Documents">3.6.6 Here Documents</a></li> |
| <li><a id="toc-Here-Strings" href="#Here-Strings">3.6.7 Here Strings</a></li> |
| <li><a id="toc-Duplicating-File-Descriptors" href="#Duplicating-File-Descriptors">3.6.8 Duplicating File Descriptors</a></li> |
| <li><a id="toc-Moving-File-Descriptors" href="#Moving-File-Descriptors">3.6.9 Moving File Descriptors</a></li> |
| <li><a id="toc-Opening-File-Descriptors-for-Reading-and-Writing" href="#Opening-File-Descriptors-for-Reading-and-Writing">3.6.10 Opening File Descriptors for Reading and Writing</a></li> |
| </ul></li> |
| <li><a id="toc-Executing-Commands-1" href="#Executing-Commands">3.7 Executing Commands</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Simple-Command-Expansion-1" href="#Simple-Command-Expansion">3.7.1 Simple Command Expansion</a></li> |
| <li><a id="toc-Command-Search-and-Execution-1" href="#Command-Search-and-Execution">3.7.2 Command Search and Execution</a></li> |
| <li><a id="toc-Command-Execution-Environment-1" href="#Command-Execution-Environment">3.7.3 Command Execution Environment</a></li> |
| <li><a id="toc-Environment-1" href="#Environment">3.7.4 Environment</a></li> |
| <li><a id="toc-Exit-Status-1" href="#Exit-Status">3.7.5 Exit Status</a></li> |
| <li><a id="toc-Signals-1" href="#Signals">3.7.6 Signals</a></li> |
| </ul></li> |
| <li><a id="toc-Shell-Scripts-1" href="#Shell-Scripts">3.8 Shell Scripts</a></li> |
| </ul></li> |
| <li><a id="toc-Shell-Builtin-Commands-1" href="#Shell-Builtin-Commands">4 Shell Builtin Commands</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Bourne-Shell-Builtins-1" href="#Bourne-Shell-Builtins">4.1 Bourne Shell Builtins</a></li> |
| <li><a id="toc-Bash-Builtin-Commands" href="#Bash-Builtins">4.2 Bash Builtin Commands</a></li> |
| <li><a id="toc-Modifying-Shell-Behavior-1" href="#Modifying-Shell-Behavior">4.3 Modifying Shell Behavior</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-The-Set-Builtin-1" href="#The-Set-Builtin">4.3.1 The Set Builtin</a></li> |
| <li><a id="toc-The-Shopt-Builtin-1" href="#The-Shopt-Builtin">4.3.2 The Shopt Builtin</a></li> |
| </ul></li> |
| <li><a id="toc-Special-Builtins-1" href="#Special-Builtins">4.4 Special Builtins</a></li> |
| </ul></li> |
| <li><a id="toc-Shell-Variables-1" href="#Shell-Variables">5 Shell Variables</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Bourne-Shell-Variables-1" href="#Bourne-Shell-Variables">5.1 Bourne Shell Variables</a></li> |
| <li><a id="toc-Bash-Variables-1" href="#Bash-Variables">5.2 Bash Variables</a></li> |
| </ul></li> |
| <li><a id="toc-Bash-Features-2" href="#Bash-Features">6 Bash Features</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Invoking-Bash-1" href="#Invoking-Bash">6.1 Invoking Bash</a></li> |
| <li><a id="toc-Bash-Startup-Files-1" href="#Bash-Startup-Files">6.2 Bash Startup Files</a></li> |
| <li><a id="toc-Interactive-Shells-1" href="#Interactive-Shells">6.3 Interactive Shells</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-What-is-an-Interactive-Shell_003f-1" href="#What-is-an-Interactive-Shell_003f">6.3.1 What is an Interactive Shell?</a></li> |
| <li><a id="toc-Is-this-Shell-Interactive_003f-1" href="#Is-this-Shell-Interactive_003f">6.3.2 Is this Shell Interactive?</a></li> |
| <li><a id="toc-Interactive-Shell-Behavior-1" href="#Interactive-Shell-Behavior">6.3.3 Interactive Shell Behavior</a></li> |
| </ul></li> |
| <li><a id="toc-Bash-Conditional-Expressions-1" href="#Bash-Conditional-Expressions">6.4 Bash Conditional Expressions</a></li> |
| <li><a id="toc-Shell-Arithmetic-1" href="#Shell-Arithmetic">6.5 Shell Arithmetic</a></li> |
| <li><a id="toc-Aliases-1" href="#Aliases">6.6 Aliases</a></li> |
| <li><a id="toc-Arrays-1" href="#Arrays">6.7 Arrays</a></li> |
| <li><a id="toc-The-Directory-Stack-1" href="#The-Directory-Stack">6.8 The Directory Stack</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Directory-Stack-Builtins-1" href="#Directory-Stack-Builtins">6.8.1 Directory Stack Builtins</a></li> |
| </ul></li> |
| <li><a id="toc-Controlling-the-Prompt-1" href="#Controlling-the-Prompt">6.9 Controlling the Prompt</a></li> |
| <li><a id="toc-The-Restricted-Shell-1" href="#The-Restricted-Shell">6.10 The Restricted Shell</a></li> |
| <li><a id="toc-Bash-POSIX-Mode-1" href="#Bash-POSIX-Mode">6.11 Bash POSIX Mode</a></li> |
| <li><a id="toc-Shell-Compatibility-Mode-1" href="#Shell-Compatibility-Mode">6.12 Shell Compatibility Mode</a></li> |
| </ul></li> |
| <li><a id="toc-Job-Control-1" href="#Job-Control">7 Job Control</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Job-Control-Basics-1" href="#Job-Control-Basics">7.1 Job Control Basics</a></li> |
| <li><a id="toc-Job-Control-Builtins-1" href="#Job-Control-Builtins">7.2 Job Control Builtins</a></li> |
| <li><a id="toc-Job-Control-Variables-1" href="#Job-Control-Variables">7.3 Job Control Variables</a></li> |
| </ul></li> |
| <li><a id="toc-Command-Line-Editing-1" href="#Command-Line-Editing">8 Command Line Editing</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Introduction-to-Line-Editing" href="#Introduction-and-Notation">8.1 Introduction to Line Editing</a></li> |
| <li><a id="toc-Readline-Interaction-1" href="#Readline-Interaction">8.2 Readline Interaction</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Readline-Bare-Essentials-1" href="#Readline-Bare-Essentials">8.2.1 Readline Bare Essentials</a></li> |
| <li><a id="toc-Readline-Movement-Commands-1" href="#Readline-Movement-Commands">8.2.2 Readline Movement Commands</a></li> |
| <li><a id="toc-Readline-Killing-Commands-1" href="#Readline-Killing-Commands">8.2.3 Readline Killing Commands</a></li> |
| <li><a id="toc-Readline-Arguments-1" href="#Readline-Arguments">8.2.4 Readline Arguments</a></li> |
| <li><a id="toc-Searching-for-Commands-in-the-History" href="#Searching">8.2.5 Searching for Commands in the History</a></li> |
| </ul></li> |
| <li><a id="toc-Readline-Init-File-1" href="#Readline-Init-File">8.3 Readline Init File</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Readline-Init-File-Syntax-1" href="#Readline-Init-File-Syntax">8.3.1 Readline Init File Syntax</a></li> |
| <li><a id="toc-Conditional-Init-Constructs-1" href="#Conditional-Init-Constructs">8.3.2 Conditional Init Constructs</a></li> |
| <li><a id="toc-Sample-Init-File-1" href="#Sample-Init-File">8.3.3 Sample Init File</a></li> |
| </ul></li> |
| <li><a id="toc-Bindable-Readline-Commands-1" href="#Bindable-Readline-Commands">8.4 Bindable Readline Commands</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Commands-For-Moving-1" href="#Commands-For-Moving">8.4.1 Commands For Moving</a></li> |
| <li><a id="toc-Commands-For-Manipulating-The-History" href="#Commands-For-History">8.4.2 Commands For Manipulating The History</a></li> |
| <li><a id="toc-Commands-For-Changing-Text" href="#Commands-For-Text">8.4.3 Commands For Changing Text</a></li> |
| <li><a id="toc-Killing-And-Yanking" href="#Commands-For-Killing">8.4.4 Killing And Yanking</a></li> |
| <li><a id="toc-Specifying-Numeric-Arguments" href="#Numeric-Arguments">8.4.5 Specifying Numeric Arguments</a></li> |
| <li><a id="toc-Letting-Readline-Type-For-You" href="#Commands-For-Completion">8.4.6 Letting Readline Type For You</a></li> |
| <li><a id="toc-Keyboard-Macros-1" href="#Keyboard-Macros">8.4.7 Keyboard Macros</a></li> |
| <li><a id="toc-Some-Miscellaneous-Commands" href="#Miscellaneous-Commands">8.4.8 Some Miscellaneous Commands</a></li> |
| </ul></li> |
| <li><a id="toc-Readline-vi-Mode-1" href="#Readline-vi-Mode">8.5 Readline vi Mode</a></li> |
| <li><a id="toc-Programmable-Completion-1" href="#Programmable-Completion">8.6 Programmable Completion</a></li> |
| <li><a id="toc-Programmable-Completion-Builtins-1" href="#Programmable-Completion-Builtins">8.7 Programmable Completion Builtins</a></li> |
| <li><a id="toc-A-Programmable-Completion-Example-1" href="#A-Programmable-Completion-Example">8.8 A Programmable Completion Example</a></li> |
| </ul></li> |
| <li><a id="toc-Using-History-Interactively-1" href="#Using-History-Interactively">9 Using History Interactively</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Bash-History-Facilities-1" href="#Bash-History-Facilities">9.1 Bash History Facilities</a></li> |
| <li><a id="toc-Bash-History-Builtins-1" href="#Bash-History-Builtins">9.2 Bash History Builtins</a></li> |
| <li><a id="toc-History-Expansion" href="#History-Interaction">9.3 History Expansion</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Event-Designators-1" href="#Event-Designators">9.3.1 Event Designators</a></li> |
| <li><a id="toc-Word-Designators-1" href="#Word-Designators">9.3.2 Word Designators</a></li> |
| <li><a id="toc-Modifiers-1" href="#Modifiers">9.3.3 Modifiers</a></li> |
| </ul></li> |
| </ul></li> |
| <li><a id="toc-Installing-Bash-1" href="#Installing-Bash">10 Installing Bash</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Basic-Installation-1" href="#Basic-Installation">10.1 Basic Installation</a></li> |
| <li><a id="toc-Compilers-and-Options-1" href="#Compilers-and-Options">10.2 Compilers and Options</a></li> |
| <li><a id="toc-Compiling-For-Multiple-Architectures-1" href="#Compiling-For-Multiple-Architectures">10.3 Compiling For Multiple Architectures</a></li> |
| <li><a id="toc-Installation-Names-1" href="#Installation-Names">10.4 Installation Names</a></li> |
| <li><a id="toc-Specifying-the-System-Type-1" href="#Specifying-the-System-Type">10.5 Specifying the System Type</a></li> |
| <li><a id="toc-Sharing-Defaults-1" href="#Sharing-Defaults">10.6 Sharing Defaults</a></li> |
| <li><a id="toc-Operation-Controls-1" href="#Operation-Controls">10.7 Operation Controls</a></li> |
| <li><a id="toc-Optional-Features-1" href="#Optional-Features">10.8 Optional Features</a></li> |
| </ul></li> |
| <li><a id="toc-Reporting-Bugs-1" href="#Reporting-Bugs">Appendix A Reporting Bugs</a></li> |
| <li><a id="toc-Major-Differences-From-The-Bourne-Shell-1" href="#Major-Differences-From-The-Bourne-Shell">Appendix B Major Differences From The Bourne Shell</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Implementation-Differences-From-The-SVR4_002e2-Shell" href="#Implementation-Differences-From-The-SVR4_002e2-Shell">B.1 Implementation Differences From The SVR4.2 Shell</a></li> |
| </ul></li> |
| <li><a id="toc-GNU-Free-Documentation-License-1" href="#GNU-Free-Documentation-License">Appendix C GNU Free Documentation License</a></li> |
| <li><a id="toc-Indexes-1" href="#Indexes">Appendix D Indexes</a> |
| <ul class="toc-numbered-mark"> |
| <li><a id="toc-Index-of-Shell-Builtin-Commands" href="#Builtin-Index" rel="index">D.1 Index of Shell Builtin Commands</a></li> |
| <li><a id="toc-Index-of-Shell-Reserved-Words" href="#Reserved-Word-Index" rel="index">D.2 Index of Shell Reserved Words</a></li> |
| <li><a id="toc-Parameter-and-Variable-Index" href="#Variable-Index" rel="index">D.3 Parameter and Variable Index</a></li> |
| <li><a id="toc-Function-Index-1" href="#Function-Index" rel="index">D.4 Function Index</a></li> |
| <li><a id="toc-Concept-Index-1" href="#Concept-Index" rel="index">D.5 Concept Index</a></li> |
| </ul></li> |
| </ul> |
| </div> |
| </div> |
| <hr> |
| <div class="chapter-level-extent" id="Introduction"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Definitions" accesskey="n" rel="next">Definitions</a>, Up: <a href="#Top" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h2 class="chapter" id="Introduction-1"><span>1 Introduction<a class="copiable-link" href="#Introduction-1"> ¶</a></span></h2> |
| |
| <ul class="mini-toc"> |
| <li><a href="#What-is-Bash_003f" accesskey="1">What is Bash?</a></li> |
| <li><a href="#What-is-a-shell_003f" accesskey="2">What is a shell?</a></li> |
| </ul> |
| <hr> |
| <div class="section-level-extent" id="What-is-Bash_003f"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#What-is-a-shell_003f" accesskey="n" rel="next">What is a shell?</a>, Up: <a href="#Introduction" accesskey="u" rel="up">Introduction</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="What-is-Bash_003f-1"><span>1.1 What is Bash?<a class="copiable-link" href="#What-is-Bash_003f-1"> ¶</a></span></h3> |
| |
| <p>Bash is the shell, or command language interpreter, |
| for the <small class="sc">GNU</small> operating system. |
| The name is an acronym for the ‘<samp class="samp">Bourne-Again SHell</samp>’, |
| a pun on Stephen Bourne, the author of the direct ancestor of |
| the current Unix shell <code class="code">sh</code>, |
| which appeared in the Seventh Edition Bell Labs Research version |
| of Unix. |
| </p> |
| <p>Bash is largely compatible with <code class="code">sh</code> and incorporates useful |
| features from the Korn shell <code class="code">ksh</code> and the C shell <code class="code">csh</code>. |
| It is intended to be a conformant implementation of the <small class="sc">IEEE</small> |
| <small class="sc">POSIX</small> Shell and Tools portion of the <small class="sc">IEEE</small> <small class="sc">POSIX</small> |
| specification (<small class="sc">IEEE</small> Standard 1003.1). |
| It offers functional improvements over <code class="code">sh</code> for both interactive and |
| programming use. |
| </p> |
| <p>While the <small class="sc">GNU</small> operating system provides other shells, including |
| a version of <code class="code">csh</code>, Bash is the default shell. |
| Like other <small class="sc">GNU</small> software, Bash is quite portable. It currently runs |
| on nearly every version of Unix and a few other operating systems − |
| independently-supported ports exist for <small class="sc">MS-DOS</small>, <small class="sc">OS/2</small>, |
| and Windows platforms. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="What-is-a-shell_003f"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#What-is-Bash_003f" accesskey="p" rel="prev">What is Bash?</a>, Up: <a href="#Introduction" accesskey="u" rel="up">Introduction</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="What-is-a-shell_003f-1"><span>1.2 What is a shell?<a class="copiable-link" href="#What-is-a-shell_003f-1"> ¶</a></span></h3> |
| |
| <p>At its base, a shell is simply a macro processor that executes |
| commands. The term macro processor means functionality where text |
| and symbols are expanded to create larger expressions. |
| </p> |
| <p>A Unix shell is both a command interpreter and a programming |
| language. As a command interpreter, the shell provides the user |
| interface to the rich set of <small class="sc">GNU</small> utilities. The programming |
| language features allow these utilities to be combined. |
| Files containing commands can be created, and become |
| commands themselves. These new commands have the same status as |
| system commands in directories such as <samp class="file">/bin</samp>, allowing users |
| or groups to establish custom environments to automate their common |
| tasks. |
| </p> |
| <p>Shells may be used interactively or non-interactively. In |
| interactive mode, they accept input typed from the keyboard. |
| When executing non-interactively, shells execute commands read |
| from a file. |
| </p> |
| <p>A shell allows execution of <small class="sc">GNU</small> commands, both synchronously and |
| asynchronously. |
| The shell waits for synchronous commands to complete before accepting |
| more input; asynchronous commands continue to execute in parallel |
| with the shell while it reads and executes additional commands. |
| The <em class="dfn">redirection</em> constructs permit |
| fine-grained control of the input and output of those commands. |
| Moreover, the shell allows control over the contents of commands’ |
| environments. |
| </p> |
| <p>Shells also provide a small set of built-in |
| commands (<em class="dfn">builtins</em>) implementing functionality impossible |
| or inconvenient to obtain via separate utilities. |
| For example, <code class="code">cd</code>, <code class="code">break</code>, <code class="code">continue</code>, and |
| <code class="code">exec</code> cannot be implemented outside of the shell because |
| they directly manipulate the shell itself. |
| The <code class="code">history</code>, <code class="code">getopts</code>, <code class="code">kill</code>, or <code class="code">pwd</code> |
| builtins, among others, could be implemented in separate utilities, |
| but they are more convenient to use as builtin commands. |
| All of the shell builtins are described in |
| subsequent sections. |
| </p> |
| <p>While executing commands is essential, most of the power (and |
| complexity) of shells is due to their embedded programming |
| languages. Like any high-level language, the shell provides |
| variables, flow control constructs, quoting, and functions. |
| </p> |
| <p>Shells offer features geared specifically for |
| interactive use rather than to augment the programming language. |
| These interactive features include job control, command line |
| editing, command history and aliases. Each of these features is |
| described in this manual. |
| </p> |
| <hr> |
| </div> |
| </div> |
| <div class="chapter-level-extent" id="Definitions"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Basic-Shell-Features" accesskey="n" rel="next">Basic Shell Features</a>, Previous: <a href="#Introduction" accesskey="p" rel="prev">Introduction</a>, Up: <a href="#Top" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h2 class="chapter" id="Definitions-1"><span>2 Definitions<a class="copiable-link" href="#Definitions-1"> ¶</a></span></h2> |
| <p>These definitions are used throughout the remainder of this manual. |
| </p> |
| <dl class="table"> |
| <dt><a id="index-POSIX"></a><span><code class="code">POSIX</code><a class="copiable-link" href="#index-POSIX"> ¶</a></span></dt> |
| <dd><p>A family of open system standards based on Unix. Bash |
| is primarily concerned with the Shell and Utilities portion of the |
| <small class="sc">POSIX</small> 1003.1 standard. |
| </p> |
| </dd> |
| <dt><code class="code">blank</code></dt> |
| <dd><p>A space or tab character. |
| </p> |
| </dd> |
| <dt><a id="index-builtin-1"></a><span><code class="code">builtin</code><a class="copiable-link" href="#index-builtin-1"> ¶</a></span></dt> |
| <dd><p>A command that is implemented internally by the shell itself, rather |
| than by an executable program somewhere in the file system. |
| </p> |
| </dd> |
| <dt><a id="index-control-operator"></a><span><code class="code">control operator</code><a class="copiable-link" href="#index-control-operator"> ¶</a></span></dt> |
| <dd><p>A <code class="code">token</code> that performs a control function. It is a <code class="code">newline</code> |
| or one of the following: |
| ‘<samp class="samp">||</samp>’, ‘<samp class="samp">&&</samp>’, ‘<samp class="samp">&</samp>’, ‘<samp class="samp">;</samp>’, ‘<samp class="samp">;;</samp>’, ‘<samp class="samp">;&</samp>’, ‘<samp class="samp">;;&</samp>’, |
| ‘<samp class="samp">|</samp>’, ‘<samp class="samp">|&</samp>’, ‘<samp class="samp">(</samp>’, or ‘<samp class="samp">)</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-exit-status"></a><span><code class="code">exit status</code><a class="copiable-link" href="#index-exit-status"> ¶</a></span></dt> |
| <dd><p>The value returned by a command to its caller. The value is restricted |
| to eight bits, so the maximum value is 255. |
| </p> |
| </dd> |
| <dt><a id="index-field"></a><span><code class="code">field</code><a class="copiable-link" href="#index-field"> ¶</a></span></dt> |
| <dd><p>A unit of text that is the result of one of the shell expansions. After |
| expansion, when executing a command, the resulting fields are used as |
| the command name and arguments. |
| </p> |
| </dd> |
| <dt><a id="index-filename"></a><span><code class="code">filename</code><a class="copiable-link" href="#index-filename"> ¶</a></span></dt> |
| <dd><p>A string of characters used to identify a file. |
| </p> |
| </dd> |
| <dt><a id="index-job"></a><span><code class="code">job</code><a class="copiable-link" href="#index-job"> ¶</a></span></dt> |
| <dd><p>A set of processes comprising a pipeline, and any processes descended |
| from it, that are all in the same process group. |
| </p> |
| </dd> |
| <dt><a id="index-job-control"></a><span><code class="code">job control</code><a class="copiable-link" href="#index-job-control"> ¶</a></span></dt> |
| <dd><p>A mechanism by which users can selectively stop (suspend) and restart |
| (resume) execution of processes. |
| </p> |
| </dd> |
| <dt><a id="index-metacharacter"></a><span><code class="code">metacharacter</code><a class="copiable-link" href="#index-metacharacter"> ¶</a></span></dt> |
| <dd><p>A character that, when unquoted, separates words. A metacharacter is |
| a <code class="code">space</code>, <code class="code">tab</code>, <code class="code">newline</code>, or one of the following characters: |
| ‘<samp class="samp">|</samp>’, ‘<samp class="samp">&</samp>’, ‘<samp class="samp">;</samp>’, ‘<samp class="samp">(</samp>’, ‘<samp class="samp">)</samp>’, ‘<samp class="samp"><</samp>’, or |
| ‘<samp class="samp">></samp>’. |
| </p> |
| </dd> |
| <dt><a class="index-entry-id" id="index-identifier"></a> |
| <a id="index-name"></a><span><code class="code">name</code><a class="copiable-link" href="#index-name"> ¶</a></span></dt> |
| <dd><p>A <code class="code">word</code> consisting solely of letters, numbers, and underscores, |
| and beginning with a letter or underscore. <code class="code">Name</code>s are used as |
| shell variable and function names. |
| Also referred to as an <code class="code">identifier</code>. |
| </p> |
| </dd> |
| <dt><a id="index-operator_002c-shell"></a><span><code class="code">operator</code><a class="copiable-link" href="#index-operator_002c-shell"> ¶</a></span></dt> |
| <dd><p>A <code class="code">control operator</code> or a <code class="code">redirection operator</code>. |
| See <a class="xref" href="#Redirections">Redirections</a>, for a list of redirection operators. |
| Operators contain at least one unquoted <code class="code">metacharacter</code>. |
| </p> |
| </dd> |
| <dt><a id="index-process-group"></a><span><code class="code">process group</code><a class="copiable-link" href="#index-process-group"> ¶</a></span></dt> |
| <dd><p>A collection of related processes each having the same process |
| group <small class="sc">ID</small>. |
| </p> |
| </dd> |
| <dt><a id="index-process-group-ID"></a><span><code class="code">process group ID</code><a class="copiable-link" href="#index-process-group-ID"> ¶</a></span></dt> |
| <dd><p>A unique identifier that represents a <code class="code">process group</code> |
| during its lifetime. |
| </p> |
| </dd> |
| <dt><a id="index-reserved-word"></a><span><code class="code">reserved word</code><a class="copiable-link" href="#index-reserved-word"> ¶</a></span></dt> |
| <dd><p>A <code class="code">word</code> that has a special meaning to the shell. Most reserved |
| words introduce shell flow control constructs, such as <code class="code">for</code> and |
| <code class="code">while</code>. |
| </p> |
| </dd> |
| <dt><a id="index-return-status"></a><span><code class="code">return status</code><a class="copiable-link" href="#index-return-status"> ¶</a></span></dt> |
| <dd><p>A synonym for <code class="code">exit status</code>. |
| </p> |
| </dd> |
| <dt><a id="index-signal"></a><span><code class="code">signal</code><a class="copiable-link" href="#index-signal"> ¶</a></span></dt> |
| <dd><p>A mechanism by which a process may be notified by the kernel |
| of an event occurring in the system. |
| </p> |
| </dd> |
| <dt><a id="index-special-builtin"></a><span><code class="code">special builtin</code><a class="copiable-link" href="#index-special-builtin"> ¶</a></span></dt> |
| <dd><p>A shell builtin command that has been classified as special by the |
| <small class="sc">POSIX</small> standard. |
| </p> |
| </dd> |
| <dt><a id="index-token"></a><span><code class="code">token</code><a class="copiable-link" href="#index-token"> ¶</a></span></dt> |
| <dd><p>A sequence of characters considered a single unit by the shell. |
| It is either a <code class="code">word</code> or an <code class="code">operator</code>. |
| </p> |
| </dd> |
| <dt><a id="index-word"></a><span><code class="code">word</code><a class="copiable-link" href="#index-word"> ¶</a></span></dt> |
| <dd><p>A sequence of characters treated as a unit by the shell. |
| Words may not include unquoted <code class="code">metacharacters</code>. |
| </p></dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="chapter-level-extent" id="Basic-Shell-Features"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Shell-Builtin-Commands" accesskey="n" rel="next">Shell Builtin Commands</a>, Previous: <a href="#Definitions" accesskey="p" rel="prev">Definitions</a>, Up: <a href="#Top" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h2 class="chapter" id="Basic-Shell-Features-1"><span>3 Basic Shell Features<a class="copiable-link" href="#Basic-Shell-Features-1"> ¶</a></span></h2> |
| <a class="index-entry-id" id="index-Bourne-shell"></a> |
| |
| <p>Bash is an acronym for ‘<samp class="samp">Bourne-Again SHell</samp>’. |
| The Bourne shell is |
| the traditional Unix shell originally written by Stephen Bourne. |
| All of the Bourne shell builtin commands are available in Bash, |
| The rules for evaluation and quoting are taken from the <small class="sc">POSIX</small> |
| specification for the ‘standard’ Unix shell. |
| </p> |
| <p>This chapter briefly summarizes the shell’s ‘building blocks’: |
| commands, control structures, shell functions, shell <i class="i">parameters</i>, |
| shell expansions, |
| <i class="i">redirections</i>, which are a way to direct input and output from |
| and to named files, and how the shell executes commands. |
| </p> |
| |
| <ul class="mini-toc"> |
| <li><a href="#Shell-Syntax" accesskey="1">Shell Syntax</a></li> |
| <li><a href="#Shell-Commands" accesskey="2">Shell Commands</a></li> |
| <li><a href="#Shell-Functions" accesskey="3">Shell Functions</a></li> |
| <li><a href="#Shell-Parameters" accesskey="4">Shell Parameters</a></li> |
| <li><a href="#Shell-Expansions" accesskey="5">Shell Expansions</a></li> |
| <li><a href="#Redirections" accesskey="6">Redirections</a></li> |
| <li><a href="#Executing-Commands" accesskey="7">Executing Commands</a></li> |
| <li><a href="#Shell-Scripts" accesskey="8">Shell Scripts</a></li> |
| </ul> |
| <hr> |
| <div class="section-level-extent" id="Shell-Syntax"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Shell-Commands" accesskey="n" rel="next">Shell Commands</a>, Up: <a href="#Basic-Shell-Features" accesskey="u" rel="up">Basic Shell Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Shell-Syntax-1"><span>3.1 Shell Syntax<a class="copiable-link" href="#Shell-Syntax-1"> ¶</a></span></h3> |
| |
| <p>When the shell reads input, it proceeds through a |
| sequence of operations. If the input indicates the beginning of a |
| comment, the shell ignores the comment symbol (‘<samp class="samp">#</samp>’), and the rest |
| of that line. |
| </p> |
| <p>Otherwise, roughly speaking, the shell reads its input and |
| divides the input into words and operators, employing the quoting rules |
| to select which meanings to assign various words and characters. |
| </p> |
| <p>The shell then parses these tokens into commands and other constructs, |
| removes the special meaning of certain words or characters, expands |
| others, redirects input and output as needed, executes the specified |
| command, waits for the command’s exit status, and makes that exit status |
| available for further inspection or processing. |
| </p> |
| <ul class="mini-toc"> |
| <li><a href="#Shell-Operation" accesskey="1">Shell Operation</a></li> |
| <li><a href="#Quoting" accesskey="2">Quoting</a></li> |
| <li><a href="#Comments" accesskey="3">Comments</a></li> |
| </ul> |
| <hr> |
| <div class="subsection-level-extent" id="Shell-Operation"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Quoting" accesskey="n" rel="next">Quoting</a>, Up: <a href="#Shell-Syntax" accesskey="u" rel="up">Shell Syntax</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Shell-Operation-1"><span>3.1.1 Shell Operation<a class="copiable-link" href="#Shell-Operation-1"> ¶</a></span></h4> |
| |
| <p>The following is a brief description of the shell’s operation when it |
| reads and executes a command. Basically, the shell does the |
| following: |
| </p> |
| <ol class="enumerate"> |
| <li> Reads its input from a file (see <a class="pxref" href="#Shell-Scripts">Shell Scripts</a>), from a string |
| supplied as an argument to the <samp class="option">-c</samp> invocation option |
| (see <a class="pxref" href="#Invoking-Bash">Invoking Bash</a>), or from the user’s terminal. |
| |
| </li><li> Breaks the input into words and operators, obeying the quoting rules |
| described in <a class="ref" href="#Quoting">Quoting</a>. These tokens are separated by |
| <code class="code">metacharacters</code>. Alias expansion is performed by this step |
| (see <a class="pxref" href="#Aliases">Aliases</a>). |
| |
| </li><li> Parses the tokens into simple and compound commands |
| (see <a class="pxref" href="#Shell-Commands">Shell Commands</a>). |
| |
| </li><li> Performs the various shell expansions (see <a class="pxref" href="#Shell-Expansions">Shell Expansions</a>), breaking |
| the expanded tokens into lists of filenames (see <a class="pxref" href="#Filename-Expansion">Filename Expansion</a>) |
| and commands and arguments. |
| |
| </li><li> Performs any necessary redirections (see <a class="pxref" href="#Redirections">Redirections</a>) and removes |
| the redirection operators and their operands from the argument list. |
| |
| </li><li> Executes the command (see <a class="pxref" href="#Executing-Commands">Executing Commands</a>). |
| |
| </li><li> Optionally waits for the command to complete and collects its exit |
| status (see <a class="pxref" href="#Exit-Status">Exit Status</a>). |
| |
| </li></ol> |
| |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Quoting"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Comments" accesskey="n" rel="next">Comments</a>, Previous: <a href="#Shell-Operation" accesskey="p" rel="prev">Shell Operation</a>, Up: <a href="#Shell-Syntax" accesskey="u" rel="up">Shell Syntax</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Quoting-1"><span>3.1.2 Quoting<a class="copiable-link" href="#Quoting-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-quoting"></a> |
| |
| <p>Quoting is used to remove the special meaning of certain |
| characters or words to the shell. Quoting can be used to |
| disable special treatment for special characters, to prevent |
| reserved words from being recognized as such, and to prevent |
| parameter expansion. |
| </p> |
| <p>Each of the shell metacharacters (see <a class="pxref" href="#Definitions">Definitions</a>) |
| has special meaning to the shell and must be quoted if it is to |
| represent itself. |
| When the command history expansion facilities are being used |
| (see <a class="pxref" href="#History-Interaction">History Expansion</a>), the |
| <em class="dfn">history expansion</em> character, usually ‘<samp class="samp">!</samp>’, must be quoted |
| to prevent history expansion. See <a class="xref" href="#Bash-History-Facilities">Bash History Facilities</a>, for |
| more details concerning history expansion. |
| </p> |
| <p>There are three quoting mechanisms: the |
| <em class="dfn">escape character</em>, single quotes, and double quotes. |
| </p> |
| <ul class="mini-toc"> |
| <li><a href="#Escape-Character" accesskey="1">Escape Character</a></li> |
| <li><a href="#Single-Quotes" accesskey="2">Single Quotes</a></li> |
| <li><a href="#Double-Quotes" accesskey="3">Double Quotes</a></li> |
| <li><a href="#ANSI_002dC-Quoting" accesskey="4">ANSI-C Quoting</a></li> |
| <li><a href="#Locale-Translation" accesskey="5">Locale-Specific Translation</a></li> |
| </ul> |
| <hr> |
| <div class="subsubsection-level-extent" id="Escape-Character"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Single-Quotes" accesskey="n" rel="next">Single Quotes</a>, Up: <a href="#Quoting" accesskey="u" rel="up">Quoting</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsubsection" id="Escape-Character-1"><span>3.1.2.1 Escape Character<a class="copiable-link" href="#Escape-Character-1"> ¶</a></span></h4> |
| <p>A non-quoted backslash ‘<samp class="samp">\</samp>’ is the Bash escape character. |
| It preserves the literal value of the next character that follows, |
| with the exception of <code class="code">newline</code>. If a <code class="code">\newline</code> pair |
| appears, and the backslash itself is not quoted, the <code class="code">\newline</code> |
| is treated as a line continuation (that is, it is removed from |
| the input stream and effectively ignored). |
| </p> |
| <hr> |
| </div> |
| <div class="subsubsection-level-extent" id="Single-Quotes"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Double-Quotes" accesskey="n" rel="next">Double Quotes</a>, Previous: <a href="#Escape-Character" accesskey="p" rel="prev">Escape Character</a>, Up: <a href="#Quoting" accesskey="u" rel="up">Quoting</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsubsection" id="Single-Quotes-1"><span>3.1.2.2 Single Quotes<a class="copiable-link" href="#Single-Quotes-1"> ¶</a></span></h4> |
| |
| <p>Enclosing characters in single quotes (‘<samp class="samp">'</samp>’) preserves the literal value |
| of each character within the quotes. A single quote may not occur |
| between single quotes, even when preceded by a backslash. |
| </p> |
| <hr> |
| </div> |
| <div class="subsubsection-level-extent" id="Double-Quotes"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#ANSI_002dC-Quoting" accesskey="n" rel="next">ANSI-C Quoting</a>, Previous: <a href="#Single-Quotes" accesskey="p" rel="prev">Single Quotes</a>, Up: <a href="#Quoting" accesskey="u" rel="up">Quoting</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsubsection" id="Double-Quotes-1"><span>3.1.2.3 Double Quotes<a class="copiable-link" href="#Double-Quotes-1"> ¶</a></span></h4> |
| |
| <p>Enclosing characters in double quotes (‘<samp class="samp">"</samp>’) preserves the literal value |
| of all characters within the quotes, with the exception of |
| ‘<samp class="samp">$</samp>’, ‘<samp class="samp">`</samp>’, ‘<samp class="samp">\</samp>’, |
| and, when history expansion is enabled, ‘<samp class="samp">!</samp>’. |
| When the shell is in |
| <small class="sc">POSIX</small> mode (see <a class="pxref" href="#Bash-POSIX-Mode">Bash POSIX Mode</a>), |
| the ‘<samp class="samp">!</samp>’ has no special meaning |
| within double quotes, even when history expansion is enabled. |
| The characters ‘<samp class="samp">$</samp>’ and ‘<samp class="samp">`</samp>’ |
| retain their special meaning within double quotes (see <a class="pxref" href="#Shell-Expansions">Shell Expansions</a>). |
| The backslash retains its special meaning only when followed by one of |
| the following characters: |
| ‘<samp class="samp">$</samp>’, ‘<samp class="samp">`</samp>’, ‘<samp class="samp">"</samp>’, ‘<samp class="samp">\</samp>’, or <code class="code">newline</code>. |
| Within double quotes, backslashes that are followed by one of these |
| characters are removed. Backslashes preceding characters without a |
| special meaning are left unmodified. |
| A double quote may be quoted within double quotes by preceding it with |
| a backslash. |
| If enabled, history expansion will be performed unless an ‘<samp class="samp">!</samp>’ |
| appearing in double quotes is escaped using a backslash. |
| The backslash preceding the ‘<samp class="samp">!</samp>’ is not removed. |
| </p> |
| <p>The special parameters ‘<samp class="samp">*</samp>’ and ‘<samp class="samp">@</samp>’ have special meaning |
| when in double quotes (see <a class="pxref" href="#Shell-Parameter-Expansion">Shell Parameter Expansion</a>). |
| </p> |
| <hr> |
| </div> |
| <div class="subsubsection-level-extent" id="ANSI_002dC-Quoting"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Locale-Translation" accesskey="n" rel="next">Locale-Specific Translation</a>, Previous: <a href="#Double-Quotes" accesskey="p" rel="prev">Double Quotes</a>, Up: <a href="#Quoting" accesskey="u" rel="up">Quoting</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsubsection" id="ANSI_002dC-Quoting-1"><span>3.1.2.4 ANSI-C Quoting<a class="copiable-link" href="#ANSI_002dC-Quoting-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-quoting_002c-ANSI"></a> |
| |
| <p>Character sequences of the form $’<var class="var">string</var>’ are treated as a special |
| kind of single quotes. |
| The sequence expands to <var class="var">string</var>, with backslash-escaped characters |
| in <var class="var">string</var> replaced as specified by the ANSI C standard. |
| Backslash escape sequences, if present, are decoded as follows: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">\a</code></dt> |
| <dd><p>alert (bell) |
| </p></dd> |
| <dt><code class="code">\b</code></dt> |
| <dd><p>backspace |
| </p></dd> |
| <dt><code class="code">\e</code></dt> |
| <dt><code class="code">\E</code></dt> |
| <dd><p>an escape character (not ANSI C) |
| </p></dd> |
| <dt><code class="code">\f</code></dt> |
| <dd><p>form feed |
| </p></dd> |
| <dt><code class="code">\n</code></dt> |
| <dd><p>newline |
| </p></dd> |
| <dt><code class="code">\r</code></dt> |
| <dd><p>carriage return |
| </p></dd> |
| <dt><code class="code">\t</code></dt> |
| <dd><p>horizontal tab |
| </p></dd> |
| <dt><code class="code">\v</code></dt> |
| <dd><p>vertical tab |
| </p></dd> |
| <dt><code class="code">\\</code></dt> |
| <dd><p>backslash |
| </p></dd> |
| <dt><code class="code">\'</code></dt> |
| <dd><p>single quote |
| </p></dd> |
| <dt><code class="code">\"</code></dt> |
| <dd><p>double quote |
| </p></dd> |
| <dt><code class="code">\?</code></dt> |
| <dd><p>question mark |
| </p></dd> |
| <dt><code class="code">\<var class="var">nnn</var></code></dt> |
| <dd><p>the eight-bit character whose value is the octal value <var class="var">nnn</var> |
| (one to three octal digits) |
| </p></dd> |
| <dt><code class="code">\x<var class="var">HH</var></code></dt> |
| <dd><p>the eight-bit character whose value is the hexadecimal value <var class="var">HH</var> |
| (one or two hex digits) |
| </p></dd> |
| <dt><code class="code">\u<var class="var">HHHH</var></code></dt> |
| <dd><p>the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value |
| <var class="var">HHHH</var> (one to four hex digits) |
| </p></dd> |
| <dt><code class="code">\U<var class="var">HHHHHHHH</var></code></dt> |
| <dd><p>the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value |
| <var class="var">HHHHHHHH</var> (one to eight hex digits) |
| </p></dd> |
| <dt><code class="code">\c<var class="var">x</var></code></dt> |
| <dd><p>a control-<var class="var">x</var> character |
| </p></dd> |
| </dl> |
| |
| <p>The expanded result is single-quoted, as if the dollar sign had not |
| been present. |
| </p> |
| <hr> |
| </div> |
| <div class="subsubsection-level-extent" id="Locale-Translation"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#ANSI_002dC-Quoting" accesskey="p" rel="prev">ANSI-C Quoting</a>, Up: <a href="#Quoting" accesskey="u" rel="up">Quoting</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsubsection" id="Locale_002dSpecific-Translation"><span>3.1.2.5 Locale-Specific Translation<a class="copiable-link" href="#Locale_002dSpecific-Translation"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-localization"></a> |
| <a class="index-entry-id" id="index-internationalization"></a> |
| <a class="index-entry-id" id="index-native-languages"></a> |
| <a class="index-entry-id" id="index-translation_002c-native-languages"></a> |
| |
| <p>Prefixing a double-quoted string with a dollar sign (‘<samp class="samp">$</samp>’), such |
| as <code class="verb">$"hello, world"</code>, |
| will cause the string to be translated according to the current locale. |
| The <code class="code">gettext</code> infrastructure performs the lookup and |
| translation, using the <code class="code">LC_MESSAGES</code>, <code class="code">TEXTDOMAINDIR</code>, |
| and <code class="code">TEXTDOMAIN</code> shell variables, as explained below. |
| See the gettext documentation for additional details not covered here. |
| If the current locale is <code class="code">C</code> or <code class="code">POSIX</code>, |
| if there are no translations available, |
| of if the string is not translated, |
| the dollar sign is ignored. |
| Since this is a form of double quoting, the string remains double-quoted |
| by default, whether or not it is translated and replaced. |
| If the <code class="code">noexpand_translation</code> option is enabled |
| using the <code class="code">shopt</code> builtin (see <a class="pxref" href="#The-Shopt-Builtin">The Shopt Builtin</a>), |
| translated strings are single-quoted instead of double-quoted. |
| </p> |
| <p>The rest of this section is a brief overview of how you use gettext to |
| create translations for strings in a shell script named <var class="var">scriptname</var>. |
| There are more details in the gettext documentation. |
| </p> |
| <hr> |
| <a class="node-id" id="Creating-Internationalized-Scripts"></a><div class="nav-panel"> |
| <p> |
| [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="node"><span>Creating Internationalized Scripts<a class="copiable-link" href="#Creating-Internationalized-Scripts"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-internationalized-scripts"></a> |
| <a class="index-entry-id" id="index-string-translations"></a> |
| <p>Once you’ve marked the strings in your script |
| that you want to translate using $"...", |
| you create a gettext "template" file using the command |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">bash --dump-po-strings <var class="var">scriptname</var> > <var class="var">domain</var>.pot |
| </pre></div> |
| |
| <p>The <var class="var">domain</var> is your <em class="dfn">message domain</em>. |
| It’s just an arbitrary string that’s used to identify the files gettext |
| needs, like a package or script name. |
| It needs to be unique among all |
| the message domains on systems where you install the translations, so |
| gettext knows which translations correspond to your script. |
| You’ll use the template file to create translations for each target language. |
| The template file conventionally has the suffix ‘<samp class="samp">.pot</samp>’. |
| </p> |
| <p>You copy this template file to a separate file for each target language |
| you want to support (called "PO" files, which use the suffix ‘<samp class="samp">.po</samp>’). |
| PO files use various naming conventions, but |
| when you are working to translate a template file into a particular |
| language, you first copy the template file to a file whose name is the |
| language you want to target, with the ‘<samp class="samp">.po</samp>’ suffix. |
| For instance, the Spanish translations of your strings would be |
| in a file named ‘<samp class="samp">es.po</samp>’, and to get started using a message |
| domain named "example," you would run |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">cp example.pot es.po |
| </pre></div> |
| |
| <p>Ultimately, PO files are often named <var class="var">domain</var>.po and installed in |
| directories that contain multiple translation files for a particular language. |
| </p> |
| <p>Whichever naming convention you choose, you will need to translate the |
| strings in the PO files into the appropriate languages. |
| This has to be done manually. |
| </p> |
| <p>When you have the translations and PO files complete, you’ll use the |
| gettext tools to produce what are called "MO" files, which are compiled |
| versions of the PO files the gettext tools use to look up translations |
| efficiently. |
| MO files are also called "message catalog" files. |
| You use the <code class="command">msgfmt</code> program to do this. |
| For instance, if you had a file with Spanish translations, you could run |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">msgfmt -o es.mo es.po |
| </pre></div> |
| |
| <p>to produce the corresponding MO file. |
| </p> |
| <p>Once you have the MO files, you decide where to install them and use the |
| <code class="code">TEXTDOMAINDIR</code> shell variable to tell the gettext tools where they are. |
| Make sure to use the same message domain to name the MO files |
| as you did for the PO files when you install them. |
| </p> |
| <a class="index-entry-id" id="index-LANG"></a> |
| <a class="index-entry-id" id="index-LC_005fMESSAGES"></a> |
| <a class="index-entry-id" id="index-TEXTDOMAIN"></a> |
| <a class="index-entry-id" id="index-TEXTDOMAINDIR"></a> |
| <p>Your users will use the <code class="env">LANG</code> or <code class="env">LC_MESSAGES</code> shell variables to |
| select the desired language. |
| </p> |
| <p>You set the <code class="env">TEXTDOMAIN</code> variable to the script’s message domain. |
| As above, you use the message domain to name your translation files. |
| </p> |
| <p>You, or possibly your users, set the <code class="env">TEXTDOMAINDIR</code> variable to the |
| name of a directory where the message catalog files are stored. |
| If you install the message files into the system’s standard message catalog |
| directory, you don’t need to worry about this variable. |
| </p> |
| <p>The directory where the message catalog files are stored varies between |
| systems. |
| Some use the message catalog selected by the <code class="env">LC_MESSAGES</code> |
| shell variable. |
| Others create the name of the message catalog from the value of the |
| <code class="env">TEXTDOMAIN</code> shell variable, possibly adding the ‘<samp class="samp">.mo</samp>’ suffix. |
| If you use the <code class="env">TEXTDOMAIN</code> variable, you may need to set the |
| <code class="env">TEXTDOMAINDIR</code> variable to the location of the message catalog files, |
| as above. |
| It’s common to use both variables in this fashion: |
| <code class="env">$TEXTDOMAINDIR</code>/<code class="env">$LC_MESSAGES</code>/LC_MESSAGES/<code class="env">$TEXTDOMAIN</code>.mo. |
| </p> |
| <p>If you used that last convention, and you wanted to store the message |
| catalog files with Spanish (es) and Esperanto (eo) translations into a |
| local directory you use for custom translation files, you could run |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">TEXTDOMAIN=example |
| TEXTDOMAINDIR=/usr/local/share/locale |
| |
| cp es.mo ${TEXTDOMAINDIR}/es/LC_MESSAGES/${TEXTDOMAIN}.mo |
| cp eo.mo ${TEXTDOMAINDIR}/eo/LC_MESSAGES/${TEXTDOMAIN}.mo |
| </pre></div> |
| |
| <p>When all of this is done, and the message catalog files containing the |
| compiled translations are installed in the correct location, |
| your users will be able to see translated strings |
| in any of the supported languages by setting the <code class="env">LANG</code> or |
| <code class="env">LC_MESSAGES</code> environment variables before running your script. |
| </p> |
| <hr> |
| </div> |
| </div> |
| <div class="subsection-level-extent" id="Comments"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Quoting" accesskey="p" rel="prev">Quoting</a>, Up: <a href="#Shell-Syntax" accesskey="u" rel="up">Shell Syntax</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Comments-1"><span>3.1.3 Comments<a class="copiable-link" href="#Comments-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-comments_002c-shell"></a> |
| |
| <p>In a non-interactive shell, or an interactive shell in which the |
| <code class="code">interactive_comments</code> option to the <code class="code">shopt</code> |
| builtin is enabled (see <a class="pxref" href="#The-Shopt-Builtin">The Shopt Builtin</a>), |
| a word beginning with ‘<samp class="samp">#</samp>’ |
| causes that word and all remaining characters on that line to |
| be ignored. An interactive shell without the <code class="code">interactive_comments</code> |
| option enabled does not allow comments. The <code class="code">interactive_comments</code> |
| option is on by default in interactive shells. |
| See <a class="xref" href="#Interactive-Shells">Interactive Shells</a>, for a description of what makes |
| a shell interactive. |
| </p> |
| <hr> |
| </div> |
| </div> |
| <div class="section-level-extent" id="Shell-Commands"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Shell-Functions" accesskey="n" rel="next">Shell Functions</a>, Previous: <a href="#Shell-Syntax" accesskey="p" rel="prev">Shell Syntax</a>, Up: <a href="#Basic-Shell-Features" accesskey="u" rel="up">Basic Shell Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Shell-Commands-1"><span>3.2 Shell Commands<a class="copiable-link" href="#Shell-Commands-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-commands_002c-shell"></a> |
| |
| <p>A simple shell command such as <code class="code">echo a b c</code> consists of the command |
| itself followed by arguments, separated by spaces. |
| </p> |
| <p>More complex shell commands are composed of simple commands arranged together |
| in a variety of ways: in a pipeline in which the output of one command |
| becomes the input of a second, in a loop or conditional construct, or in |
| some other grouping. |
| </p> |
| |
| <ul class="mini-toc"> |
| <li><a href="#Reserved-Words" accesskey="1">Reserved Words</a></li> |
| <li><a href="#Simple-Commands" accesskey="2">Simple Commands</a></li> |
| <li><a href="#Pipelines" accesskey="3">Pipelines</a></li> |
| <li><a href="#Lists" accesskey="4">Lists of Commands</a></li> |
| <li><a href="#Compound-Commands" accesskey="5">Compound Commands</a></li> |
| <li><a href="#Coprocesses" accesskey="6">Coprocesses</a></li> |
| <li><a href="#GNU-Parallel" accesskey="7">GNU Parallel</a></li> |
| </ul> |
| <hr> |
| <div class="subsection-level-extent" id="Reserved-Words"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Simple-Commands" accesskey="n" rel="next">Simple Commands</a>, Up: <a href="#Shell-Commands" accesskey="u" rel="up">Shell Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Reserved-Words-1"><span>3.2.1 Reserved Words<a class="copiable-link" href="#Reserved-Words-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-reserved-words"></a> |
| |
| <p>Reserved words are words that have special meaning to the shell. |
| They are used to begin and end the shell’s compound commands. |
| </p> |
| <p>The following words are recognized as reserved when unquoted and |
| the first word of a command (see below for exceptions): |
| </p> |
| <table class="multitable"> |
| <tbody><tr><td width="10%"><code class="code">if</code></td><td width="10%"><code class="code">then</code></td><td width="10%"><code class="code">elif</code></td><td width="10%"><code class="code">else</code></td><td width="12%"><code class="code">fi</code></td><td width="10%"><code class="code">time</code></td></tr> |
| <tr><td width="10%"><code class="code">for</code></td><td width="10%"><code class="code">in</code></td><td width="10%"><code class="code">until</code></td><td width="10%"><code class="code">while</code></td><td width="12%"><code class="code">do</code></td><td width="10%"><code class="code">done</code></td></tr> |
| <tr><td width="10%"><code class="code">case</code></td><td width="10%"><code class="code">esac</code></td><td width="10%"><code class="code">coproc</code></td><td width="10%"><code class="code">select</code></td><td width="12%"><code class="code">function</code></td></tr> |
| <tr><td width="10%"><code class="code">{</code></td><td width="10%"><code class="code">}</code></td><td width="10%"><code class="code">[[</code></td><td width="10%"><code class="code">]]</code></td><td width="12%"><code class="code">!</code></td></tr> |
| </tbody> |
| </table> |
| |
| <p><code class="code">in</code> is recognized as a reserved word if it is the third word of a |
| <code class="code">case</code> or <code class="code">select</code> command. |
| <code class="code">in</code> and <code class="code">do</code> are recognized as reserved |
| words if they are the third word in a <code class="code">for</code> command. |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Simple-Commands"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Pipelines" accesskey="n" rel="next">Pipelines</a>, Previous: <a href="#Reserved-Words" accesskey="p" rel="prev">Reserved Words</a>, Up: <a href="#Shell-Commands" accesskey="u" rel="up">Shell Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Simple-Commands-1"><span>3.2.2 Simple Commands<a class="copiable-link" href="#Simple-Commands-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-commands_002c-simple"></a> |
| |
| <p>A simple command is the kind of command encountered most often. |
| It’s just a sequence of words separated by <code class="code">blank</code>s, terminated |
| by one of the shell’s control operators (see <a class="pxref" href="#Definitions">Definitions</a>). The |
| first word generally specifies a command to be executed, with the |
| rest of the words being that command’s arguments. |
| </p> |
| <p>The return status (see <a class="pxref" href="#Exit-Status">Exit Status</a>) of a simple command is |
| its exit status as provided |
| by the <small class="sc">POSIX</small> 1003.1 <code class="code">waitpid</code> function, or 128+<var class="var">n</var> if |
| the command was terminated by signal <var class="var">n</var>. |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Pipelines"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Lists" accesskey="n" rel="next">Lists of Commands</a>, Previous: <a href="#Simple-Commands" accesskey="p" rel="prev">Simple Commands</a>, Up: <a href="#Shell-Commands" accesskey="u" rel="up">Shell Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Pipelines-1"><span>3.2.3 Pipelines<a class="copiable-link" href="#Pipelines-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-pipeline"></a> |
| <a class="index-entry-id" id="index-commands_002c-pipelines"></a> |
| |
| <p>A <code class="code">pipeline</code> is a sequence of one or more commands separated by |
| one of the control operators ‘<samp class="samp">|</samp>’ or ‘<samp class="samp">|&</samp>’. |
| </p> |
| <a class="index-entry-id" id="index-time"></a> |
| <a class="index-entry-id" id="index-_0021"></a> |
| <a class="index-entry-id" id="index-command-timing"></a> |
| <p>The format for a pipeline is |
| </p><div class="example"> |
| <pre class="example-preformatted">[time [-p]] [!] <var class="var">command1</var> [ | or |& <var class="var">command2</var> ] ... |
| </pre></div> |
| |
| <p>The output of each command in the pipeline is connected via a pipe |
| to the input of the next command. |
| That is, each command reads the previous command’s output. This |
| connection is performed before any redirections specified by |
| <var class="var">command1</var>. |
| </p> |
| <p>If ‘<samp class="samp">|&</samp>’ is used, <var class="var">command1</var>’s standard error, in addition to |
| its standard output, is connected to |
| <var class="var">command2</var>’s standard input through the pipe; |
| it is shorthand for <code class="code">2>&1 |</code>. |
| This implicit redirection of the standard error to the standard output is |
| performed after any redirections specified by <var class="var">command1</var>. |
| </p> |
| <p>The reserved word <code class="code">time</code> causes timing statistics |
| to be printed for the pipeline once it finishes. |
| The statistics currently consist of elapsed (wall-clock) time and |
| user and system time consumed by the command’s execution. |
| The <samp class="option">-p</samp> option changes the output format to that specified |
| by <small class="sc">POSIX</small>. |
| When the shell is in <small class="sc">POSIX</small> mode (see <a class="pxref" href="#Bash-POSIX-Mode">Bash POSIX Mode</a>), |
| it does not recognize <code class="code">time</code> as a reserved word if the next |
| token begins with a ‘<samp class="samp">-</samp>’. |
| The <code class="env">TIMEFORMAT</code> variable may be set to a format string that |
| specifies how the timing information should be displayed. |
| See <a class="xref" href="#Bash-Variables">Bash Variables</a>, for a description of the available formats. |
| The use of <code class="code">time</code> as a reserved word permits the timing of |
| shell builtins, shell functions, and pipelines. An external |
| <code class="code">time</code> command cannot time these easily. |
| </p> |
| <p>When the shell is in <small class="sc">POSIX</small> mode (see <a class="pxref" href="#Bash-POSIX-Mode">Bash POSIX Mode</a>), <code class="code">time</code> |
| may be followed by a newline. In this case, the shell displays the |
| total user and system time consumed by the shell and its children. |
| The <code class="env">TIMEFORMAT</code> variable may be used to specify the format of |
| the time information. |
| </p> |
| <p>If the pipeline is not executed asynchronously (see <a class="pxref" href="#Lists">Lists of Commands</a>), the |
| shell waits for all commands in the pipeline to complete. |
| </p> |
| <p>Each command in a multi-command pipeline, |
| where pipes are created, |
| is executed in its own <em class="dfn">subshell</em>, which is a |
| separate process (see <a class="pxref" href="#Command-Execution-Environment">Command Execution Environment</a>). |
| If the <code class="code">lastpipe</code> option is enabled using the <code class="code">shopt</code> builtin |
| (see <a class="pxref" href="#The-Shopt-Builtin">The Shopt Builtin</a>), |
| the last element of a pipeline may be run by the shell process |
| when job control is not active. |
| </p> |
| <p>The exit |
| status of a pipeline is the exit status of the last command in the |
| pipeline, unless the <code class="code">pipefail</code> option is enabled |
| (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>). |
| If <code class="code">pipefail</code> is enabled, the pipeline’s return status is the |
| value of the last (rightmost) command to exit with a non-zero status, |
| or zero if all commands exit successfully. |
| If the reserved word ‘<samp class="samp">!</samp>’ precedes the pipeline, the |
| exit status is the logical negation of the exit status as described |
| above. |
| The shell waits for all commands in the pipeline to terminate before |
| returning a value. |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Lists"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Compound-Commands" accesskey="n" rel="next">Compound Commands</a>, Previous: <a href="#Pipelines" accesskey="p" rel="prev">Pipelines</a>, Up: <a href="#Shell-Commands" accesskey="u" rel="up">Shell Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Lists-of-Commands"><span>3.2.4 Lists of Commands<a class="copiable-link" href="#Lists-of-Commands"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-commands_002c-lists"></a> |
| |
| <p>A <code class="code">list</code> is a sequence of one or more pipelines separated by one |
| of the operators ‘<samp class="samp">;</samp>’, ‘<samp class="samp">&</samp>’, ‘<samp class="samp">&&</samp>’, or ‘<samp class="samp">||</samp>’, |
| and optionally terminated by one of ‘<samp class="samp">;</samp>’, ‘<samp class="samp">&</samp>’, or a |
| <code class="code">newline</code>. |
| </p> |
| <p>Of these list operators, ‘<samp class="samp">&&</samp>’ and ‘<samp class="samp">||</samp>’ |
| have equal precedence, followed by ‘<samp class="samp">;</samp>’ and ‘<samp class="samp">&</samp>’, |
| which have equal precedence. |
| </p> |
| <p>A sequence of one or more newlines may appear in a <code class="code">list</code> |
| to delimit commands, equivalent to a semicolon. |
| </p> |
| <p>If a command is terminated by the control operator ‘<samp class="samp">&</samp>’, |
| the shell executes the command asynchronously in a subshell. |
| This is known as executing the command in the <em class="dfn">background</em>, |
| and these are referred to as <em class="dfn">asynchronous</em> commands. |
| The shell does not wait for the command to finish, and the return |
| status is 0 (true). |
| When job control is not active (see <a class="pxref" href="#Job-Control">Job Control</a>), |
| the standard input for asynchronous commands, in the absence of any |
| explicit redirections, is redirected from <code class="code">/dev/null</code>. |
| </p> |
| <p>Commands separated by a ‘<samp class="samp">;</samp>’ are executed sequentially; the shell |
| waits for each command to terminate in turn. The return status is the |
| exit status of the last command executed. |
| </p> |
| <p><small class="sc">AND</small> and <small class="sc">OR</small> lists are sequences of one or more pipelines |
| separated by the control operators ‘<samp class="samp">&&</samp>’ and ‘<samp class="samp">||</samp>’, |
| respectively. <small class="sc">AND</small> and <small class="sc">OR</small> lists are executed with left |
| associativity. |
| </p> |
| <p>An <small class="sc">AND</small> list has the form |
| </p><div class="example"> |
| <pre class="example-preformatted"><var class="var">command1</var> && <var class="var">command2</var> |
| </pre></div> |
| |
| <p><var class="var">command2</var> is executed if, and only if, <var class="var">command1</var> |
| returns an exit status of zero (success). |
| </p> |
| <p>An <small class="sc">OR</small> list has the form |
| </p><div class="example"> |
| <pre class="example-preformatted"><var class="var">command1</var> || <var class="var">command2</var> |
| </pre></div> |
| |
| <p><var class="var">command2</var> is executed if, and only if, <var class="var">command1</var> |
| returns a non-zero exit status. |
| </p> |
| <p>The return status of |
| <small class="sc">AND</small> and <small class="sc">OR</small> lists is the exit status of the last command |
| executed in the list. |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Compound-Commands"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Coprocesses" accesskey="n" rel="next">Coprocesses</a>, Previous: <a href="#Lists" accesskey="p" rel="prev">Lists of Commands</a>, Up: <a href="#Shell-Commands" accesskey="u" rel="up">Shell Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Compound-Commands-1"><span>3.2.5 Compound Commands<a class="copiable-link" href="#Compound-Commands-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-commands_002c-compound"></a> |
| |
| |
| <p>Compound commands are the shell programming language constructs. |
| Each construct begins with a reserved word or control operator and is |
| terminated by a corresponding reserved word or operator. |
| Any redirections (see <a class="pxref" href="#Redirections">Redirections</a>) associated with a compound command |
| apply to all commands within that compound command unless explicitly overridden. |
| </p> |
| <p>In most cases a list of commands in a compound command’s description may be |
| separated from the rest of the command by one or more newlines, and may be |
| followed by a newline in place of a semicolon. |
| </p> |
| <p>Bash provides looping constructs, conditional commands, and mechanisms |
| to group commands and execute them as a unit. |
| </p> |
| <ul class="mini-toc"> |
| <li><a href="#Looping-Constructs" accesskey="1">Looping Constructs</a></li> |
| <li><a href="#Conditional-Constructs" accesskey="2">Conditional Constructs</a></li> |
| <li><a href="#Command-Grouping" accesskey="3">Grouping Commands</a></li> |
| </ul> |
| <hr> |
| <div class="subsubsection-level-extent" id="Looping-Constructs"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Conditional-Constructs" accesskey="n" rel="next">Conditional Constructs</a>, Up: <a href="#Compound-Commands" accesskey="u" rel="up">Compound Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsubsection" id="Looping-Constructs-1"><span>3.2.5.1 Looping Constructs<a class="copiable-link" href="#Looping-Constructs-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-commands_002c-looping"></a> |
| |
| <p>Bash supports the following looping constructs. |
| </p> |
| <p>Note that wherever a ‘<samp class="samp">;</samp>’ appears in the description of a |
| command’s syntax, it may be replaced with one or more newlines. |
| </p> |
| <dl class="table"> |
| <dt><a class="index-entry-id" id="index-do"></a> |
| <a class="index-entry-id" id="index-done"></a> |
| <a id="index-until"></a><span><code class="code">until</code><a class="copiable-link" href="#index-until"> ¶</a></span></dt> |
| <dd><p>The syntax of the <code class="code">until</code> command is: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">until <var class="var">test-commands</var>; do <var class="var">consequent-commands</var>; done |
| </pre></div> |
| |
| <p>Execute <var class="var">consequent-commands</var> as long as |
| <var class="var">test-commands</var> has an exit status which is not zero. |
| The return status is the exit status of the last command executed |
| in <var class="var">consequent-commands</var>, or zero if none was executed. |
| </p> |
| </dd> |
| <dt><a id="index-while"></a><span><code class="code">while</code><a class="copiable-link" href="#index-while"> ¶</a></span></dt> |
| <dd><p>The syntax of the <code class="code">while</code> command is: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">while <var class="var">test-commands</var>; do <var class="var">consequent-commands</var>; done |
| </pre></div> |
| |
| <p>Execute <var class="var">consequent-commands</var> as long as |
| <var class="var">test-commands</var> has an exit status of zero. |
| The return status is the exit status of the last command executed |
| in <var class="var">consequent-commands</var>, or zero if none was executed. |
| </p> |
| </dd> |
| <dt><a id="index-for"></a><span><code class="code">for</code><a class="copiable-link" href="#index-for"> ¶</a></span></dt> |
| <dd><p>The syntax of the <code class="code">for</code> command is: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">for <var class="var">name</var> [ [in [<var class="var">words</var> ...] ] ; ] do <var class="var">commands</var>; done |
| </pre></div> |
| |
| <p>Expand <var class="var">words</var> (see <a class="pxref" href="#Shell-Expansions">Shell Expansions</a>), and execute <var class="var">commands</var> |
| once for each member |
| in the resultant list, with <var class="var">name</var> bound to the current member. |
| If ‘<samp class="samp">in <var class="var">words</var></samp>’ is not present, the <code class="code">for</code> command |
| executes the <var class="var">commands</var> once for each positional parameter that is |
| set, as if ‘<samp class="samp">in "$@"</samp>’ had been specified |
| (see <a class="pxref" href="#Special-Parameters">Special Parameters</a>). |
| </p> |
| <p>The return status is the exit status of the last command that executes. |
| If there are no items in the expansion of <var class="var">words</var>, no commands are |
| executed, and the return status is zero. |
| </p> |
| <p>An alternate form of the <code class="code">for</code> command is also supported: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">for (( <var class="var">expr1</var> ; <var class="var">expr2</var> ; <var class="var">expr3</var> )) ; do <var class="var">commands</var> ; done |
| </pre></div> |
| |
| <p>First, the arithmetic expression <var class="var">expr1</var> is evaluated according |
| to the rules described below (see <a class="pxref" href="#Shell-Arithmetic">Shell Arithmetic</a>). |
| The arithmetic expression <var class="var">expr2</var> is then evaluated repeatedly |
| until it evaluates to zero. |
| Each time <var class="var">expr2</var> evaluates to a non-zero value, <var class="var">commands</var> are |
| executed and the arithmetic expression <var class="var">expr3</var> is evaluated. |
| If any expression is omitted, it behaves as if it evaluates to 1. |
| The return value is the exit status of the last command in <var class="var">commands</var> |
| that is executed, or false if any of the expressions is invalid. |
| </p></dd> |
| </dl> |
| |
| <p>The <code class="code">break</code> and <code class="code">continue</code> builtins (see <a class="pxref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>) |
| may be used to control loop execution. |
| </p> |
| <hr> |
| </div> |
| <div class="subsubsection-level-extent" id="Conditional-Constructs"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Command-Grouping" accesskey="n" rel="next">Grouping Commands</a>, Previous: <a href="#Looping-Constructs" accesskey="p" rel="prev">Looping Constructs</a>, Up: <a href="#Compound-Commands" accesskey="u" rel="up">Compound Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsubsection" id="Conditional-Constructs-1"><span>3.2.5.2 Conditional Constructs<a class="copiable-link" href="#Conditional-Constructs-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-commands_002c-conditional"></a> |
| |
| <dl class="table"> |
| <dt><a class="index-entry-id" id="index-then"></a> |
| <a class="index-entry-id" id="index-else"></a> |
| <a class="index-entry-id" id="index-elif"></a> |
| <a class="index-entry-id" id="index-fi"></a> |
| <a id="index-if"></a><span><code class="code">if</code><a class="copiable-link" href="#index-if"> ¶</a></span></dt> |
| <dd><p>The syntax of the <code class="code">if</code> command is: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">if <var class="var">test-commands</var>; then |
| <var class="var">consequent-commands</var>; |
| [elif <var class="var">more-test-commands</var>; then |
| <var class="var">more-consequents</var>;] |
| [else <var class="var">alternate-consequents</var>;] |
| fi |
| </pre></div> |
| |
| <p>The <var class="var">test-commands</var> list is executed, and if its return status is zero, |
| the <var class="var">consequent-commands</var> list is executed. |
| If <var class="var">test-commands</var> returns a non-zero status, each <code class="code">elif</code> list |
| is executed in turn, and if its exit status is zero, |
| the corresponding <var class="var">more-consequents</var> is executed and the |
| command completes. |
| If ‘<samp class="samp">else <var class="var">alternate-consequents</var></samp>’ is present, and |
| the final command in the final <code class="code">if</code> or <code class="code">elif</code> clause |
| has a non-zero exit status, then <var class="var">alternate-consequents</var> is executed. |
| The return status is the exit status of the last command executed, or |
| zero if no condition tested true. |
| </p> |
| </dd> |
| <dt><a class="index-entry-id" id="index-in"></a> |
| <a class="index-entry-id" id="index-esac"></a> |
| <a id="index-case"></a><span><code class="code">case</code><a class="copiable-link" href="#index-case"> ¶</a></span></dt> |
| <dd><p>The syntax of the <code class="code">case</code> command is: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">case <var class="var">word</var> in |
| [ [(] <var class="var">pattern</var> [| <var class="var">pattern</var>]...) <var class="var">command-list</var> ;;]... |
| esac |
| </pre></div> |
| |
| <p><code class="code">case</code> will selectively execute the <var class="var">command-list</var> corresponding to |
| the first <var class="var">pattern</var> that matches <var class="var">word</var>. |
| The match is performed according |
| to the rules described below in <a class="ref" href="#Pattern-Matching">Pattern Matching</a>. |
| If the <code class="code">nocasematch</code> shell option |
| (see the description of <code class="code">shopt</code> in <a class="ref" href="#The-Shopt-Builtin">The Shopt Builtin</a>) |
| is enabled, the match is performed without regard to the case |
| of alphabetic characters. |
| The ‘<samp class="samp">|</samp>’ is used to separate multiple patterns, and the ‘<samp class="samp">)</samp>’ |
| operator terminates a pattern list. |
| A list of patterns and an associated command-list is known |
| as a <var class="var">clause</var>. |
| </p> |
| <p>Each clause must be terminated with ‘<samp class="samp">;;</samp>’, ‘<samp class="samp">;&</samp>’, or ‘<samp class="samp">;;&</samp>’. |
| The <var class="var">word</var> undergoes tilde expansion, parameter expansion, command |
| substitution, arithmetic expansion, and quote removal |
| (see <a class="pxref" href="#Shell-Parameter-Expansion">Shell Parameter Expansion</a>) |
| before matching is attempted. |
| Each <var class="var">pattern</var> undergoes tilde expansion, parameter expansion, |
| command substitution, arithmetic expansion, process substitution, and |
| quote removal. |
| </p> |
| <p>There may be an arbitrary number of <code class="code">case</code> clauses, each terminated |
| by a ‘<samp class="samp">;;</samp>’, ‘<samp class="samp">;&</samp>’, or ‘<samp class="samp">;;&</samp>’. |
| The first pattern that matches determines the |
| command-list that is executed. |
| It’s a common idiom to use ‘<samp class="samp">*</samp>’ as the final pattern to define the |
| default case, since that pattern will always match. |
| </p> |
| <p>Here is an example using <code class="code">case</code> in a script that could be used to |
| describe one interesting feature of an animal: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">echo -n "Enter the name of an animal: " |
| read ANIMAL |
| echo -n "The $ANIMAL has " |
| case $ANIMAL in |
| horse | dog | cat) echo -n "four";; |
| man | kangaroo ) echo -n "two";; |
| *) echo -n "an unknown number of";; |
| esac |
| echo " legs." |
| </pre></div> |
| |
| |
| <p>If the ‘<samp class="samp">;;</samp>’ operator is used, no subsequent matches are attempted after |
| the first pattern match. |
| Using ‘<samp class="samp">;&</samp>’ in place of ‘<samp class="samp">;;</samp>’ causes execution to continue with |
| the <var class="var">command-list</var> associated with the next clause, if any. |
| Using ‘<samp class="samp">;;&</samp>’ in place of ‘<samp class="samp">;;</samp>’ causes the shell to test the patterns |
| in the next clause, if any, and execute any associated <var class="var">command-list</var> |
| on a successful match, |
| continuing the case statement execution as if the pattern list had not matched. |
| </p> |
| <p>The return status is zero if no <var class="var">pattern</var> is matched. Otherwise, the |
| return status is the exit status of the <var class="var">command-list</var> executed. |
| </p> |
| </dd> |
| <dt><a id="index-select"></a><span><code class="code">select</code><a class="copiable-link" href="#index-select"> ¶</a></span></dt> |
| <dd> |
| <p>The <code class="code">select</code> construct allows the easy generation of menus. |
| It has almost the same syntax as the <code class="code">for</code> command: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">select <var class="var">name</var> [in <var class="var">words</var> ...]; do <var class="var">commands</var>; done |
| </pre></div> |
| |
| <p>The list of words following <code class="code">in</code> is expanded, generating a list |
| of items, and the set of expanded words is printed on the standard |
| error output stream, each preceded by a number. If the |
| ‘<samp class="samp">in <var class="var">words</var></samp>’ is omitted, the positional parameters are printed, |
| as if ‘<samp class="samp">in "$@"</samp>’ had been specified. |
| <code class="code">select</code> then displays the <code class="env">PS3</code> |
| prompt and reads a line from the standard input. |
| If the line consists of a number corresponding to one of the displayed |
| words, then the value of <var class="var">name</var> is set to that word. |
| If the line is empty, the words and prompt are displayed again. |
| If <code class="code">EOF</code> is read, the <code class="code">select</code> command completes and returns 1. |
| Any other value read causes <var class="var">name</var> to be set to null. |
| The line read is saved in the variable <code class="env">REPLY</code>. |
| </p> |
| <p>The <var class="var">commands</var> are executed after each selection until a |
| <code class="code">break</code> command is executed, at which |
| point the <code class="code">select</code> command completes. |
| </p> |
| <p>Here is an example that allows the user to pick a filename from the |
| current directory, and displays the name and index of the file |
| selected. |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">select fname in *; |
| do |
| echo you picked $fname \($REPLY\) |
| break; |
| done |
| </pre></div> |
| |
| </dd> |
| <dt><code class="code">((…))</code></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">(( <var class="var">expression</var> )) |
| </pre></div> |
| |
| <p>The arithmetic <var class="var">expression</var> is evaluated according to the rules |
| described below (see <a class="pxref" href="#Shell-Arithmetic">Shell Arithmetic</a>). |
| The <var class="var">expression</var> undergoes the same expansions |
| as if it were within double quotes, |
| but double quote characters in <var class="var">expression</var> are not treated specially |
| are removed. |
| If the value of the expression is non-zero, the return status is 0; |
| otherwise the return status is 1. |
| </p> |
| |
| </dd> |
| <dt><a class="index-entry-id" id="index-_005d_005d"></a> |
| <a id="index-_005b_005b"></a><span><code class="code">[[…]]</code><a class="copiable-link" href="#index-_005b_005b"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">[[ <var class="var">expression</var> ]] |
| </pre></div> |
| |
| <p>Return a status of 0 or 1 depending on the evaluation of |
| the conditional expression <var class="var">expression</var>. |
| Expressions are composed of the primaries described below in |
| <a class="ref" href="#Bash-Conditional-Expressions">Bash Conditional Expressions</a>. |
| The words between the <code class="code">[[</code> and <code class="code">]]</code> do not undergo word splitting |
| and filename expansion. |
| The shell performs tilde expansion, parameter and |
| variable expansion, arithmetic expansion, command substitution, process |
| substitution, and quote removal on those words |
| (the expansions that would occur if the words were enclosed in double quotes). |
| Conditional operators such as ‘<samp class="samp">-f</samp>’ must be unquoted to be recognized |
| as primaries. |
| </p> |
| <p>When used with <code class="code">[[</code>, the ‘<samp class="samp"><</samp>’ and ‘<samp class="samp">></samp>’ operators sort |
| lexicographically using the current locale. |
| </p> |
| <p>When the ‘<samp class="samp">==</samp>’ and ‘<samp class="samp">!=</samp>’ operators are used, the string to the |
| right of the operator is considered a pattern and matched according |
| to the rules described below in <a class="ref" href="#Pattern-Matching">Pattern Matching</a>, |
| as if the <code class="code">extglob</code> shell option were enabled. |
| The ‘<samp class="samp">=</samp>’ operator is identical to ‘<samp class="samp">==</samp>’. |
| If the <code class="code">nocasematch</code> shell option |
| (see the description of <code class="code">shopt</code> in <a class="ref" href="#The-Shopt-Builtin">The Shopt Builtin</a>) |
| is enabled, the match is performed without regard to the case |
| of alphabetic characters. |
| The return value is 0 if the string matches (‘<samp class="samp">==</samp>’) or does not |
| match (‘<samp class="samp">!=</samp>’) the pattern, and 1 otherwise. |
| </p> |
| <p>If you quote any part of the pattern, |
| using any of the shell’s quoting mechanisms, |
| the quoted portion is matched literally. |
| This means every character in the quoted portion matches itself, |
| instead of having any special pattern matching meaning. |
| </p> |
| <p>An additional binary operator, ‘<samp class="samp">=~</samp>’, is available, with the same |
| precedence as ‘<samp class="samp">==</samp>’ and ‘<samp class="samp">!=</samp>’. |
| When you use ‘<samp class="samp">=~</samp>’, the string to the right of the operator is considered |
| a <small class="sc">POSIX</small> extended regular expression pattern and matched accordingly |
| (using the <small class="sc">POSIX</small> <code class="code">regcomp</code> and <code class="code">regexec</code> interfaces |
| usually described in <i class="i">regex</i>(3)). |
| The return value is 0 if the string matches the pattern, and 1 if it does not. |
| If the regular expression is syntactically incorrect, the conditional |
| expression returns 2. |
| If the <code class="code">nocasematch</code> shell option |
| (see the description of <code class="code">shopt</code> in <a class="ref" href="#The-Shopt-Builtin">The Shopt Builtin</a>) |
| is enabled, the match is performed without regard to the case |
| of alphabetic characters. |
| </p> |
| <p>You can quote any part of the pattern |
| to force the quoted portion to be matched literally |
| instead of as a regular expression (see above). |
| If the pattern is stored in a shell variable, quoting the variable |
| expansion forces the entire pattern to be matched literally. |
| </p> |
| <p>The pattern will match if it matches any part of the string. |
| If you want to force the pattern to match the entire string, |
| anchor the pattern using the ‘<samp class="samp">^</samp>’ and ‘<samp class="samp">$</samp>’ regular expression |
| operators. |
| </p> |
| <p>For example, the following will match a line |
| (stored in the shell variable <code class="code">line</code>) |
| if there is a sequence of characters anywhere in the value consisting of |
| any number, including zero, of |
| characters in the <code class="code">space</code> character class, |
| immediately followed by zero or one instances of ‘<samp class="samp">a</samp>’, |
| then a ‘<samp class="samp">b</samp>’: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">[[ $line =~ [[:space:]]*(a)?b ]] |
| </pre></div> |
| |
| <p>That means values for <code class="code">line</code> like |
| ‘<samp class="samp">aab</samp>’, ‘<samp class="samp"> aaaaaab</samp>’, ‘<samp class="samp">xaby</samp>’, and ‘<samp class="samp"> ab</samp>’ |
| will all match, |
| as will a line containing a ‘<samp class="samp">b</samp>’ anywhere in its value. |
| </p> |
| <p>If you want to match a character that’s special to the regular expression |
| grammar (‘<samp class="samp">^$|[]()\.*+?</samp>’), it has to be quoted to remove its special |
| meaning. |
| This means that in the pattern ‘<samp class="samp">xxx.txt</samp>’, the ‘<samp class="samp">.</samp>’ matches any |
| character in the string (its usual regular expression meaning), but in the |
| pattern ‘<samp class="samp">"xxx.txt"</samp>’, it can only match a literal ‘<samp class="samp">.</samp>’. |
| </p> |
| <p>Likewise, if you want to include a character in your pattern that has a |
| special meaning to the regular expression grammar, you must make sure it’s |
| not quoted. |
| If you want to anchor a pattern at the beginning or end of the string, |
| for instance, you cannot quote the ‘<samp class="samp">^</samp>’ or ‘<samp class="samp">$</samp>’ |
| characters using any form of shell quoting. |
| </p> |
| <p>If you want to match ‘<samp class="samp">initial string</samp>’ at the start of a line, |
| the following will work: |
| </p><div class="example"> |
| <pre class="example-preformatted">[[ $line =~ ^"initial string" ]] |
| </pre></div> |
| <p>but this will not: |
| </p><div class="example"> |
| <pre class="example-preformatted">[[ $line =~ "^initial string" ]] |
| </pre></div> |
| <p>because in the second example the ‘<samp class="samp">^</samp>’ is quoted and doesn’t have its |
| usual special meaning. |
| </p> |
| <p>It is sometimes difficult to specify a regular expression properly |
| without using quotes, or to keep track of the quoting used by regular |
| expressions while paying attention to |
| shell quoting and the shell’s quote removal. |
| Storing the regular expression in a shell variable is often a useful |
| way to avoid problems with quoting characters that are special to the |
| shell. |
| For example, the following is equivalent to the pattern used above: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">pattern='[[:space:]]*(a)?b' |
| [[ $line =~ $pattern ]] |
| </pre></div> |
| |
| <p>Shell programmers should take special care with backslashes, since |
| backslashes are used by both the shell and regular expressions to remove |
| the special meaning from the following character. |
| This means that after the shell’s word expansions complete |
| (see <a class="pxref" href="#Shell-Expansions">Shell Expansions</a>), |
| any backslashes remaining in parts of the pattern |
| that were originally not quoted can remove the |
| special meaning of pattern characters. |
| If any part of the pattern is quoted, the shell does its best to ensure that |
| the regular expression treats those remaining backslashes as literal, |
| if they appeared in a quoted portion. |
| </p> |
| <p>The following two sets of commands are <em class="emph">not</em> equivalent: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">pattern='\.' |
| |
| [[ . =~ $pattern ]] |
| [[ . =~ \. ]] |
| |
| [[ . =~ "$pattern" ]] |
| [[ . =~ '\.' ]] |
| </pre></div> |
| |
| <p>The first two matches will succeed, but the second two will not, because |
| in the second two the backslash will be part of the pattern to be matched. |
| In the first two examples, the pattern passed to the regular expression |
| parser is ‘<samp class="samp">\.</samp>’. The backslash removes the special meaning from |
| ‘<samp class="samp">.</samp>’, so the literal ‘<samp class="samp">.</samp>’ matches. |
| In the second two examples, the pattern passed to the regular expression |
| parser has the backslash quoted (e.g., ‘<samp class="samp">\\\.</samp>’), which will not match |
| the string, since it does not contain a backslash. |
| If the string in the first examples were anything other than ‘<samp class="samp">.</samp>’, say |
| ‘<samp class="samp">a</samp>’, the pattern would not match, because the quoted ‘<samp class="samp">.</samp>’ in the |
| pattern loses its special meaning of matching any single character. |
| </p> |
| <p>Bracket expressions in regular expressions can be sources of errors as well, |
| since characters that are normally special in regular expressions |
| lose their special meanings between brackets. |
| However, you can use bracket expressions to match special pattern characters |
| without quoting them, so they are sometimes useful for this purpose. |
| </p> |
| <p>Though it might seem like a strange way to write it, the following pattern |
| will match a ‘<samp class="samp">.</samp>’ in the string: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">[[ . =~ [.] ]] |
| </pre></div> |
| |
| <p>The shell performs any word expansions before passing the pattern |
| to the regular expression functions, |
| so you can assume that the shell’s quoting takes precedence. |
| As noted above, the regular expression parser will interpret any |
| unquoted backslashes remaining in the pattern after shell expansion |
| according to its own rules. |
| The intention is to avoid making shell programmers quote things twice |
| as much as possible, so shell quoting should be sufficient to quote |
| special pattern characters where that’s necessary. |
| </p> |
| <p>The array variable <code class="code">BASH_REMATCH</code> records which parts of the string |
| matched the pattern. |
| The element of <code class="code">BASH_REMATCH</code> with index 0 contains the portion of |
| the string matching the entire regular expression. |
| Substrings matched by parenthesized subexpressions within the regular |
| expression are saved in the remaining <code class="code">BASH_REMATCH</code> indices. |
| The element of <code class="code">BASH_REMATCH</code> with index <var class="var">n</var> is the portion of the |
| string matching the <var class="var">n</var>th parenthesized subexpression. |
| </p> |
| <p>Bash sets |
| <code class="code">BASH_REMATCH</code> |
| in the global scope; declaring it as a local variable will lead to |
| unexpected results. |
| </p> |
| <p>Expressions may be combined using the following operators, listed |
| in decreasing order of precedence: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">( <var class="var">expression</var> )</code></dt> |
| <dd><p>Returns the value of <var class="var">expression</var>. |
| This may be used to override the normal precedence of operators. |
| </p> |
| </dd> |
| <dt><code class="code">! <var class="var">expression</var></code></dt> |
| <dd><p>True if <var class="var">expression</var> is false. |
| </p> |
| </dd> |
| <dt><code class="code"><var class="var">expression1</var> && <var class="var">expression2</var></code></dt> |
| <dd><p>True if both <var class="var">expression1</var> and <var class="var">expression2</var> are true. |
| </p> |
| </dd> |
| <dt><code class="code"><var class="var">expression1</var> || <var class="var">expression2</var></code></dt> |
| <dd><p>True if either <var class="var">expression1</var> or <var class="var">expression2</var> is true. |
| </p></dd> |
| </dl> |
| |
| <p>The <code class="code">&&</code> and <code class="code">||</code> operators do not evaluate <var class="var">expression2</var> if the |
| value of <var class="var">expression1</var> is sufficient to determine the return |
| value of the entire conditional expression. |
| </p></dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="subsubsection-level-extent" id="Command-Grouping"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Conditional-Constructs" accesskey="p" rel="prev">Conditional Constructs</a>, Up: <a href="#Compound-Commands" accesskey="u" rel="up">Compound Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsubsection" id="Grouping-Commands"><span>3.2.5.3 Grouping Commands<a class="copiable-link" href="#Grouping-Commands"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-commands_002c-grouping"></a> |
| |
| <p>Bash provides two ways to group a list of commands to be executed |
| as a unit. When commands are grouped, redirections may be applied |
| to the entire command list. For example, the output of all the |
| commands in the list may be redirected to a single stream. |
| </p> |
| <dl class="table"> |
| <dt><code class="code">()</code></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">( <var class="var">list</var> ) |
| </pre></div> |
| |
| <p>Placing a list of commands between parentheses forces the shell to create |
| a subshell (see <a class="pxref" href="#Command-Execution-Environment">Command Execution Environment</a>), and each |
| of the commands in <var class="var">list</var> is executed in that subshell environment. |
| Since the <var class="var">list</var> is executed in a subshell, variable assignments do not |
| remain in effect after the subshell completes. |
| </p> |
| </dd> |
| <dt><a class="index-entry-id" id="index-_007d"></a> |
| <a id="index-_007b"></a><span><code class="code">{}</code><a class="copiable-link" href="#index-_007b"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">{ <var class="var">list</var>; } |
| </pre></div> |
| |
| <p>Placing a list of commands between curly braces causes the list to |
| be executed in the current shell context. No subshell is created. |
| The semicolon (or newline) following <var class="var">list</var> is required. |
| </p></dd> |
| </dl> |
| |
| <p>In addition to the creation of a subshell, there is a subtle difference |
| between these two constructs due to historical reasons. The braces |
| are reserved words, so they must be separated from the <var class="var">list</var> |
| by <code class="code">blank</code>s or other shell metacharacters. |
| The parentheses are operators, and are |
| recognized as separate tokens by the shell even if they are not separated |
| from the <var class="var">list</var> by whitespace. |
| </p> |
| <p>The exit status of both of these constructs is the exit status of |
| <var class="var">list</var>. |
| </p> |
| <hr> |
| </div> |
| </div> |
| <div class="subsection-level-extent" id="Coprocesses"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#GNU-Parallel" accesskey="n" rel="next">GNU Parallel</a>, Previous: <a href="#Compound-Commands" accesskey="p" rel="prev">Compound Commands</a>, Up: <a href="#Shell-Commands" accesskey="u" rel="up">Shell Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Coprocesses-1"><span>3.2.6 Coprocesses<a class="copiable-link" href="#Coprocesses-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-coprocess"></a> |
| |
| <p>A <code class="code">coprocess</code> is a shell command preceded by the <code class="code">coproc</code> |
| reserved word. |
| A coprocess is executed asynchronously in a subshell, as if the command |
| had been terminated with the ‘<samp class="samp">&</samp>’ control operator, with a two-way pipe |
| established between the executing shell and the coprocess. |
| </p> |
| <p>The syntax for a coprocess is: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">coproc [<var class="var">NAME</var>] <var class="var">command</var> [<var class="var">redirections</var>] |
| </pre></div> |
| |
| <p>This creates a coprocess named <var class="var">NAME</var>. |
| <var class="var">command</var> may be either a simple command (see <a class="pxref" href="#Simple-Commands">Simple Commands</a>) |
| or a compound command (see <a class="pxref" href="#Compound-Commands">Compound Commands</a>). |
| <var class="var">NAME</var> is a shell variable name. |
| If <var class="var">NAME</var> is not supplied, the default name is <code class="code">COPROC</code>. |
| </p> |
| <p>The recommended form to use for a coprocess is |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">coproc <var class="var">NAME</var> { <var class="var">command</var>; } |
| </pre></div> |
| |
| <p>This form is recommended because simple commands result in the coprocess |
| always being named <code class="code">COPROC</code>, and it is simpler to use and more complete |
| than the other compound commands. |
| </p> |
| <p>There are other forms of coprocesses: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">coproc <var class="var">NAME</var> <var class="var">compound-command</var> |
| coproc <var class="var">compound-command</var> |
| coproc <var class="var">simple-command</var> |
| </pre></div> |
| |
| <p>If <var class="var">command</var> is a compound command, <var class="var">NAME</var> is optional. The |
| word following <code class="code">coproc</code> determines whether that word is interpreted |
| as a variable name: it is interpreted as <var class="var">NAME</var> if it is not a |
| reserved word that introduces a compound command. |
| If <var class="var">command</var> is a simple command, <var class="var">NAME</var> is not allowed; this |
| is to avoid confusion between <var class="var">NAME</var> and the first word of the simple |
| command. |
| </p> |
| <p>When the coprocess is executed, the shell creates an array variable |
| (see <a class="pxref" href="#Arrays">Arrays</a>) |
| named <var class="var">NAME</var> in the context of the executing shell. |
| The standard output of <var class="var">command</var> |
| is connected via a pipe to a file descriptor in the executing shell, |
| and that file descriptor is assigned to <var class="var">NAME</var>[0]. |
| The standard input of <var class="var">command</var> |
| is connected via a pipe to a file descriptor in the executing shell, |
| and that file descriptor is assigned to <var class="var">NAME</var>[1]. |
| This pipe is established before any redirections specified by the |
| command (see <a class="pxref" href="#Redirections">Redirections</a>). |
| The file descriptors can be utilized as arguments to shell commands |
| and redirections using standard word expansions. |
| Other than those created to execute command and process substitutions, |
| the file descriptors are not available in subshells. |
| </p> |
| <p>The process ID of the shell spawned to execute the coprocess is |
| available as the value of the variable <code class="env"><var class="var">NAME</var>_PID</code>. |
| The <code class="code">wait</code> |
| builtin command may be used to wait for the coprocess to terminate. |
| </p> |
| <p>Since the coprocess is created as an asynchronous command, |
| the <code class="code">coproc</code> command always returns success. |
| The return status of a coprocess is the exit status of <var class="var">command</var>. |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="GNU-Parallel"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Coprocesses" accesskey="p" rel="prev">Coprocesses</a>, Up: <a href="#Shell-Commands" accesskey="u" rel="up">Shell Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="GNU-Parallel-1"><span>3.2.7 GNU Parallel<a class="copiable-link" href="#GNU-Parallel-1"> ¶</a></span></h4> |
| |
| <p>There are ways to run commands in parallel that are not built into Bash. |
| GNU Parallel is a tool to do just that. |
| </p> |
| <p>GNU Parallel, as its name suggests, can be used to build and run commands |
| in parallel. You may run the same command with different arguments, whether |
| they are filenames, usernames, hostnames, or lines read from files. GNU |
| Parallel provides shorthand references to many of the most common operations |
| (input lines, various portions of the input line, different ways to specify |
| the input source, and so on). Parallel can replace <code class="code">xargs</code> or feed |
| commands from its input sources to several different instances of Bash. |
| </p> |
| <p>For a complete description, refer to the GNU Parallel documentation, which |
| is available at |
| <a class="url" href="https://www.gnu.org/software/parallel/parallel_tutorial.html">https://www.gnu.org/software/parallel/parallel_tutorial.html</a>. |
| </p> |
| <hr> |
| </div> |
| </div> |
| <div class="section-level-extent" id="Shell-Functions"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Shell-Parameters" accesskey="n" rel="next">Shell Parameters</a>, Previous: <a href="#Shell-Commands" accesskey="p" rel="prev">Shell Commands</a>, Up: <a href="#Basic-Shell-Features" accesskey="u" rel="up">Basic Shell Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Shell-Functions-1"><span>3.3 Shell Functions<a class="copiable-link" href="#Shell-Functions-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-shell-function"></a> |
| <a class="index-entry-id" id="index-functions_002c-shell"></a> |
| |
| <p>Shell functions are a way to group commands for later execution |
| using a single name for the group. They are executed just like |
| a "regular" command. |
| When the name of a shell function is used as a simple command name, |
| the list of commands associated with that function name is executed. |
| Shell functions are executed in the current |
| shell context; no new process is created to interpret them. |
| </p> |
| <p>Functions are declared using this syntax: |
| <a class="index-entry-id" id="index-function"></a> |
| </p><div class="example"> |
| <pre class="example-preformatted"><var class="var">fname</var> () <var class="var">compound-command</var> [ <var class="var">redirections</var> ] |
| </pre></div> |
| |
| <p>or |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">function <var class="var">fname</var> [()] <var class="var">compound-command</var> [ <var class="var">redirections</var> ] |
| </pre></div> |
| |
| <p>This defines a shell function named <var class="var">fname</var>. The reserved |
| word <code class="code">function</code> is optional. |
| If the <code class="code">function</code> reserved |
| word is supplied, the parentheses are optional. |
| The <em class="dfn">body</em> of the function is the compound command |
| <var class="var">compound-command</var> (see <a class="pxref" href="#Compound-Commands">Compound Commands</a>). |
| That command is usually a <var class="var">list</var> enclosed between { and }, but |
| may be any compound command listed above. |
| If the <code class="code">function</code> reserved word is used, but the |
| parentheses are not supplied, the braces are recommended. |
| <var class="var">compound-command</var> is executed whenever <var class="var">fname</var> is specified as the |
| name of a simple command. |
| When the shell is in <small class="sc">POSIX</small> mode (see <a class="pxref" href="#Bash-POSIX-Mode">Bash POSIX Mode</a>), |
| <var class="var">fname</var> must be a valid shell name and |
| may not be the same as one of the special builtins |
| (see <a class="pxref" href="#Special-Builtins">Special Builtins</a>). |
| In default mode, a function name can be any unquoted shell word that does |
| not contain ‘<samp class="samp">$</samp>’. |
| Any redirections (see <a class="pxref" href="#Redirections">Redirections</a>) associated with the shell function |
| are performed when the function is executed. |
| A function definition may be deleted using the <samp class="option">-f</samp> option to the |
| <code class="code">unset</code> builtin (see <a class="pxref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>). |
| </p> |
| <p>The exit status of a function definition is zero unless a syntax error |
| occurs or a readonly function with the same name already exists. |
| When executed, the exit status of a function is the exit status of the |
| last command executed in the body. |
| </p> |
| <p>Note that for historical reasons, in the most common usage the curly braces |
| that surround the body of the function must be separated from the body by |
| <code class="code">blank</code>s or newlines. |
| This is because the braces are reserved words and are only recognized |
| as such when they are separated from the command list |
| by whitespace or another shell metacharacter. |
| Also, when using the braces, the <var class="var">list</var> must be terminated by a semicolon, |
| a ‘<samp class="samp">&</samp>’, or a newline. |
| </p> |
| <p>When a function is executed, the arguments to the |
| function become the positional parameters |
| during its execution (see <a class="pxref" href="#Positional-Parameters">Positional Parameters</a>). |
| The special parameter ‘<samp class="samp">#</samp>’ that expands to the number of |
| positional parameters is updated to reflect the change. |
| Special parameter <code class="code">0</code> is unchanged. |
| The first element of the <code class="env">FUNCNAME</code> variable is set to the |
| name of the function while the function is executing. |
| </p> |
| <p>All other aspects of the shell execution |
| environment are identical between a function and its caller |
| with these exceptions: |
| the <code class="env">DEBUG</code> and <code class="env">RETURN</code> traps |
| are not inherited unless the function has been given the |
| <code class="code">trace</code> attribute using the <code class="code">declare</code> builtin or |
| the <code class="code">-o functrace</code> option has been enabled with |
| the <code class="code">set</code> builtin, |
| (in which case all functions inherit the <code class="env">DEBUG</code> and <code class="env">RETURN</code> traps), |
| and the <code class="env">ERR</code> trap is not inherited unless the <code class="code">-o errtrace</code> |
| shell option has been enabled. |
| See <a class="xref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>, for the description of the |
| <code class="code">trap</code> builtin. |
| </p> |
| <p>The <code class="env">FUNCNEST</code> variable, if set to a numeric value greater |
| than 0, defines a maximum function nesting level. Function |
| invocations that exceed the limit cause the entire command to |
| abort. |
| </p> |
| <p>If the builtin command <code class="code">return</code> |
| is executed in a function, the function completes and |
| execution resumes with the next command after the function |
| call. |
| Any command associated with the <code class="code">RETURN</code> trap is executed |
| before execution resumes. |
| When a function completes, the values of the |
| positional parameters and the special parameter ‘<samp class="samp">#</samp>’ |
| are restored to the values they had prior to the function’s |
| execution. If a numeric argument is given to <code class="code">return</code>, |
| that is the function’s return status; otherwise the function’s |
| return status is the exit status of the last command executed |
| before the <code class="code">return</code>. |
| </p> |
| <p>Variables local to the function may be declared with the |
| <code class="code">local</code> builtin (<em class="dfn">local variables</em>). |
| Ordinarily, variables and their values |
| are shared between a function and its caller. |
| These variables are visible only to |
| the function and the commands it invokes. This is particularly |
| important when a shell function calls other functions. |
| </p> |
| <p>In the following description, the <em class="dfn">current scope</em> is a currently- |
| executing function. |
| Previous scopes consist of that function’s caller and so on, |
| back to the "global" scope, where the shell is not executing |
| any shell function. |
| Consequently, a local variable at the current local scope is a variable |
| declared using the <code class="code">local</code> or <code class="code">declare</code> builtins in the |
| function that is currently executing. |
| </p> |
| <p>Local variables "shadow" variables with the same name declared at |
| previous scopes. For instance, a local variable declared in a function |
| hides a global variable of the same name: references and assignments |
| refer to the local variable, leaving the global variable unmodified. |
| When the function returns, the global variable is once again visible. |
| </p> |
| <p>The shell uses <em class="dfn">dynamic scoping</em> to control a variable’s visibility |
| within functions. |
| With dynamic scoping, visible variables and their values |
| are a result of the sequence of function calls that caused execution |
| to reach the current function. |
| The value of a variable that a function sees depends |
| on its value within its caller, if any, whether that caller is |
| the "global" scope or another shell function. |
| This is also the value that a local variable |
| declaration "shadows", and the value that is restored when the function |
| returns. |
| </p> |
| <p>For example, if a variable <code class="env">var</code> is declared as local in function |
| <code class="code">func1</code>, and <code class="code">func1</code> calls another function <code class="code">func2</code>, |
| references to <code class="env">var</code> made from within <code class="code">func2</code> will resolve to the |
| local variable <code class="env">var</code> from <code class="code">func1</code>, shadowing any global variable |
| named <code class="env">var</code>. |
| </p> |
| <p>The following script demonstrates this behavior. |
| When executed, the script displays |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">In func2, var = func1 local |
| </pre></div> |
| |
| <div class="example"> |
| <pre class="example-preformatted">func1() |
| { |
| local var='func1 local' |
| func2 |
| } |
| |
| func2() |
| { |
| echo "In func2, var = $var" |
| } |
| |
| var=global |
| func1 |
| </pre></div> |
| |
| <p>The <code class="code">unset</code> builtin also acts using the same dynamic scope: if a |
| variable is local to the current scope, <code class="code">unset</code> will unset it; |
| otherwise the unset will refer to the variable found in any calling scope |
| as described above. |
| If a variable at the current local scope is unset, it will remain so |
| (appearing as unset) |
| until it is reset in that scope or until the function returns. |
| Once the function returns, any instance of the variable at a previous |
| scope will become visible. |
| If the unset acts on a variable at a previous scope, any instance of a |
| variable with that name that had been shadowed will become visible |
| (see below how <code class="code">localvar_unset</code>shell option changes this behavior). |
| </p> |
| <p>Function names and definitions may be listed with the |
| <samp class="option">-f</samp> option to the <code class="code">declare</code> (<code class="code">typeset</code>) |
| builtin command (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>). |
| The <samp class="option">-F</samp> option to <code class="code">declare</code> or <code class="code">typeset</code> |
| will list the function names only |
| (and optionally the source file and line number, if the <code class="code">extdebug</code> |
| shell option is enabled). |
| Functions may be exported so that child shell processes |
| (those created when executing a separate shell invocation) |
| automatically have them defined with the |
| <samp class="option">-f</samp> option to the <code class="code">export</code> builtin |
| (see <a class="pxref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>). |
| </p> |
| <p>Functions may be recursive. |
| The <code class="code">FUNCNEST</code> variable may be used to limit the depth of the |
| function call stack and restrict the number of function invocations. |
| By default, no limit is placed on the number of recursive calls. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Shell-Parameters"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Shell-Expansions" accesskey="n" rel="next">Shell Expansions</a>, Previous: <a href="#Shell-Functions" accesskey="p" rel="prev">Shell Functions</a>, Up: <a href="#Basic-Shell-Features" accesskey="u" rel="up">Basic Shell Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Shell-Parameters-1"><span>3.4 Shell Parameters<a class="copiable-link" href="#Shell-Parameters-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-parameters"></a> |
| <a class="index-entry-id" id="index-variable_002c-shell"></a> |
| <a class="index-entry-id" id="index-shell-variable"></a> |
| |
| |
| <p>A <em class="dfn">parameter</em> is an entity that stores values. |
| It can be a <code class="code">name</code>, a number, or one of the special characters |
| listed below. |
| A <em class="dfn">variable</em> is a parameter denoted by a <code class="code">name</code>. |
| A variable has a <code class="code">value</code> and zero or more <code class="code">attributes</code>. |
| Attributes are assigned using the <code class="code">declare</code> builtin command |
| (see the description of the <code class="code">declare</code> builtin in <a class="ref" href="#Bash-Builtins">Bash Builtin Commands</a>). |
| </p> |
| <p>A parameter is set if it has been assigned a value. The null string is |
| a valid value. Once a variable is set, it may be unset only by using |
| the <code class="code">unset</code> builtin command. |
| </p> |
| <p>A variable may be assigned to by a statement of the form |
| </p><div class="example"> |
| <pre class="example-preformatted"><var class="var">name</var>=[<var class="var">value</var>] |
| </pre></div> |
| <p>If <var class="var">value</var> |
| is not given, the variable is assigned the null string. All |
| <var class="var">value</var>s undergo tilde expansion, parameter and variable expansion, |
| command substitution, arithmetic expansion, and quote |
| removal (see <a class="pxref" href="#Shell-Parameter-Expansion">Shell Parameter Expansion</a>). |
| If the variable has its <code class="code">integer</code> |
| attribute set, then <var class="var">value</var> |
| is evaluated as an arithmetic expression even if the <code class="code">$((…))</code> |
| expansion is not used (see <a class="pxref" href="#Arithmetic-Expansion">Arithmetic Expansion</a>). |
| Word splitting and filename expansion are not performed. |
| Assignment statements may also appear as arguments to the |
| <code class="code">alias</code>, |
| <code class="code">declare</code>, <code class="code">typeset</code>, <code class="code">export</code>, <code class="code">readonly</code>, |
| and <code class="code">local</code> builtin commands (<em class="dfn">declaration</em> commands). |
| When in <small class="sc">POSIX</small> mode (see <a class="pxref" href="#Bash-POSIX-Mode">Bash POSIX Mode</a>), these builtins may appear |
| in a command after one or more instances of the <code class="code">command</code> builtin |
| and retain these assignment statement properties. |
| </p> |
| <p>In the context where an assignment statement is assigning a value |
| to a shell variable or array index (see <a class="pxref" href="#Arrays">Arrays</a>), the ‘<samp class="samp">+=</samp>’ |
| operator can be used to |
| append to or add to the variable’s previous value. |
| This includes arguments to builtin commands such as <code class="code">declare</code> that |
| accept assignment statements (declaration commands). |
| When ‘<samp class="samp">+=</samp>’ is applied to a variable for which the <code class="code">integer</code> attribute |
| has been set, <var class="var">value</var> is evaluated as an arithmetic expression and |
| added to the variable’s current value, which is also evaluated. |
| When ‘<samp class="samp">+=</samp>’ is applied to an array variable using compound assignment |
| (see <a class="pxref" href="#Arrays">Arrays</a>), the |
| variable’s value is not unset (as it is when using ‘<samp class="samp">=</samp>’), and new |
| values are appended to the array beginning at one greater than the array’s |
| maximum index (for indexed arrays), or added as additional key-value pairs |
| in an associative array. |
| When applied to a string-valued variable, <var class="var">value</var> is expanded and |
| appended to the variable’s value. |
| </p> |
| <p>A variable can be assigned the <code class="code">nameref</code> attribute using the |
| <samp class="option">-n</samp> option to the <code class="code">declare</code> or <code class="code">local</code> builtin commands |
| (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>) |
| to create a <em class="dfn">nameref</em>, or a reference to another variable. |
| This allows variables to be manipulated indirectly. |
| Whenever the nameref variable is referenced, assigned to, unset, or has |
| its attributes modified (other than using or changing the nameref |
| attribute itself), the |
| operation is actually performed on the variable specified by the nameref |
| variable’s value. |
| A nameref is commonly used within shell functions to refer to a variable |
| whose name is passed as an argument to the function. |
| For instance, if a variable name is passed to a shell function as its first |
| argument, running |
| </p><div class="example"> |
| <pre class="example-preformatted">declare -n ref=$1 |
| </pre></div> |
| <p>inside the function creates a nameref variable <code class="env">ref</code> whose value is |
| the variable name passed as the first argument. |
| References and assignments to <code class="env">ref</code>, and changes to its attributes, |
| are treated as references, assignments, and attribute modifications |
| to the variable whose name was passed as <code class="code">$1</code>. |
| </p> |
| <p>If the control variable in a <code class="code">for</code> loop has the nameref attribute, |
| the list of words can be a list of shell variables, and a name reference |
| will be established for each word in the list, in turn, when the loop is |
| executed. |
| Array variables cannot be given the nameref attribute. |
| However, nameref variables can reference array variables and subscripted |
| array variables. |
| Namerefs can be unset using the <samp class="option">-n</samp> option to the <code class="code">unset</code> builtin |
| (see <a class="pxref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>). |
| Otherwise, if <code class="code">unset</code> is executed with the name of a nameref variable |
| as an argument, the variable referenced by the nameref variable will be unset. |
| </p> |
| <ul class="mini-toc"> |
| <li><a href="#Positional-Parameters" accesskey="1">Positional Parameters</a></li> |
| <li><a href="#Special-Parameters" accesskey="2">Special Parameters</a></li> |
| </ul> |
| <hr> |
| <div class="subsection-level-extent" id="Positional-Parameters"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Special-Parameters" accesskey="n" rel="next">Special Parameters</a>, Up: <a href="#Shell-Parameters" accesskey="u" rel="up">Shell Parameters</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Positional-Parameters-1"><span>3.4.1 Positional Parameters<a class="copiable-link" href="#Positional-Parameters-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-parameters_002c-positional"></a> |
| |
| <p>A <em class="dfn">positional parameter</em> is a parameter denoted by one or more |
| digits, other than the single digit <code class="code">0</code>. Positional parameters are |
| assigned from the shell’s arguments when it is invoked, |
| and may be reassigned using the <code class="code">set</code> builtin command. |
| Positional parameter <code class="code">N</code> may be referenced as <code class="code">${N}</code>, or |
| as <code class="code">$N</code> when <code class="code">N</code> consists of a single digit. |
| Positional parameters may not be assigned to with assignment statements. |
| The <code class="code">set</code> and <code class="code">shift</code> builtins are used to set and |
| unset them (see <a class="pxref" href="#Shell-Builtin-Commands">Shell Builtin Commands</a>). |
| The positional parameters are |
| temporarily replaced when a shell function is executed |
| (see <a class="pxref" href="#Shell-Functions">Shell Functions</a>). |
| </p> |
| <p>When a positional parameter consisting of more than a single |
| digit is expanded, it must be enclosed in braces. |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Special-Parameters"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Positional-Parameters" accesskey="p" rel="prev">Positional Parameters</a>, Up: <a href="#Shell-Parameters" accesskey="u" rel="up">Shell Parameters</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Special-Parameters-1"><span>3.4.2 Special Parameters<a class="copiable-link" href="#Special-Parameters-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-parameters_002c-special"></a> |
| |
| <p>The shell treats several parameters specially. These parameters may |
| only be referenced; assignment to them is not allowed. |
| </p> |
| <dl class="vtable"> |
| <dt><a id="index-_002a"></a><span><code class="code">*</code><a class="copiable-link" href="#index-_002a"> ¶</a></span></dt> |
| <dd><a class="index-entry-id" id="index-_0024_002a"></a> |
| <p>($*) Expands to the positional parameters, starting from one. |
| When the expansion is not within double quotes, each positional parameter |
| expands to a separate word. |
| In contexts where it is performed, those words |
| are subject to further word splitting and filename expansion. |
| When the expansion occurs within double quotes, it expands to a single word |
| with the value of each parameter separated by the first character of the |
| <code class="env">IFS</code> special variable. That is, <code class="code">"$*"</code> is equivalent |
| to <code class="code">"$1<var class="var">c</var>$2<var class="var">c</var>…"</code>, where <var class="var">c</var> |
| is the first character of the value of the <code class="code">IFS</code> |
| variable. |
| If <code class="env">IFS</code> is unset, the parameters are separated by spaces. |
| If <code class="env">IFS</code> is null, the parameters are joined without intervening |
| separators. |
| </p> |
| </dd> |
| <dt><a id="index-_0040"></a><span><code class="code">@</code><a class="copiable-link" href="#index-_0040"> ¶</a></span></dt> |
| <dd><a class="index-entry-id" id="index-_0024_0040"></a> |
| <p>($@) Expands to the positional parameters, starting from one. |
| In contexts where word splitting is performed, this expands each |
| positional parameter to a separate word; if not within double |
| quotes, these words are subject to word splitting. |
| In contexts where word splitting is not performed, |
| this expands to a single word |
| with each positional parameter separated by a space. |
| When the |
| expansion occurs within double quotes, and word splitting is performed, |
| each parameter expands to a |
| separate word. That is, <code class="code">"$@"</code> is equivalent to |
| <code class="code">"$1" "$2" …</code>. |
| If the double-quoted expansion occurs within a word, the expansion of |
| the first parameter is joined with the beginning part of the original |
| word, and the expansion of the last parameter is joined with the last |
| part of the original word. |
| When there are no positional parameters, <code class="code">"$@"</code> and |
| <code class="code">$@</code> |
| expand to nothing (i.e., they are removed). |
| </p> |
| </dd> |
| <dt><a id="index-_0023"></a><span><code class="code">#</code><a class="copiable-link" href="#index-_0023"> ¶</a></span></dt> |
| <dd><a class="index-entry-id" id="index-_0024_0023"></a> |
| <p>($#) Expands to the number of positional parameters in decimal. |
| </p> |
| </dd> |
| <dt><a id="index-_003f"></a><span><code class="code">?</code><a class="copiable-link" href="#index-_003f"> ¶</a></span></dt> |
| <dd><a class="index-entry-id" id="index-_0024_003f"></a> |
| <p>($?) Expands to the exit status of the most recently executed foreground |
| pipeline. |
| </p> |
| </dd> |
| <dt><a id="index-_002d"></a><span><code class="code">-</code><a class="copiable-link" href="#index-_002d"> ¶</a></span></dt> |
| <dd><a class="index-entry-id" id="index-_0024_002d"></a> |
| <p>($-, a hyphen.) Expands to the current option flags as specified upon |
| invocation, by the <code class="code">set</code> |
| builtin command, or those set by the shell itself |
| (such as the <samp class="option">-i</samp> option). |
| </p> |
| </dd> |
| <dt><a id="index-_0024"></a><span><code class="code">$</code><a class="copiable-link" href="#index-_0024"> ¶</a></span></dt> |
| <dd><a class="index-entry-id" id="index-_0024_0024"></a> |
| <p>($$) Expands to the process <small class="sc">ID</small> of the shell. In a subshell, it |
| expands to the process <small class="sc">ID</small> of the invoking shell, not the subshell. |
| </p> |
| </dd> |
| <dt><a id="index-_0021-1"></a><span><code class="code">!</code><a class="copiable-link" href="#index-_0021-1"> ¶</a></span></dt> |
| <dd><a class="index-entry-id" id="index-_0024_0021"></a> |
| <p>($!) Expands to the process <small class="sc">ID</small> of the job most recently placed into the |
| background, whether executed as an asynchronous command or using |
| the <code class="code">bg</code> builtin (see <a class="pxref" href="#Job-Control-Builtins">Job Control Builtins</a>). |
| </p> |
| </dd> |
| <dt><a id="index-0"></a><span><code class="code">0</code><a class="copiable-link" href="#index-0"> ¶</a></span></dt> |
| <dd><a class="index-entry-id" id="index-_00240"></a> |
| <p>($0) Expands to the name of the shell or shell script. This is set at |
| shell initialization. If Bash is invoked with a file of commands |
| (see <a class="pxref" href="#Shell-Scripts">Shell Scripts</a>), <code class="code">$0</code> is set to the name of that file. |
| If Bash is started with the <samp class="option">-c</samp> option (see <a class="pxref" href="#Invoking-Bash">Invoking Bash</a>), |
| then <code class="code">$0</code> is set to the first argument after the string to be |
| executed, if one is present. Otherwise, it is set |
| to the filename used to invoke Bash, as given by argument zero. |
| </p></dd> |
| </dl> |
| |
| <hr> |
| </div> |
| </div> |
| <div class="section-level-extent" id="Shell-Expansions"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Redirections" accesskey="n" rel="next">Redirections</a>, Previous: <a href="#Shell-Parameters" accesskey="p" rel="prev">Shell Parameters</a>, Up: <a href="#Basic-Shell-Features" accesskey="u" rel="up">Basic Shell Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Shell-Expansions-1"><span>3.5 Shell Expansions<a class="copiable-link" href="#Shell-Expansions-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-expansion"></a> |
| |
| <p>Expansion is performed on the command line after it has been split into |
| <code class="code">token</code>s. There are seven kinds of expansion performed: |
| </p> |
| <ul class="itemize mark-bullet"> |
| <li>brace expansion |
| </li><li>tilde expansion |
| </li><li>parameter and variable expansion |
| </li><li>command substitution |
| </li><li>arithmetic expansion |
| </li><li>word splitting |
| </li><li>filename expansion |
| </li></ul> |
| |
| |
| <p>The order of expansions is: |
| brace expansion; |
| tilde expansion, parameter and variable expansion, arithmetic expansion, |
| and command substitution (done in a left-to-right fashion); |
| word splitting; |
| and filename expansion. |
| </p> |
| <p>On systems that can support it, there is an additional expansion |
| available: <em class="dfn">process substitution</em>. |
| This is performed at the |
| same time as tilde, parameter, variable, and arithmetic expansion and |
| command substitution. |
| </p> |
| <p>After these expansions are performed, quote characters present in the |
| original word are removed unless they have been quoted themselves |
| (<em class="dfn">quote removal</em>). |
| </p> |
| <p>Only brace expansion, word splitting, and filename expansion |
| can increase the number of words of the expansion; other expansions |
| expand a single word to a single word. |
| The only exceptions to this are the expansions of |
| <code class="code">"$@"</code> and <code class="code">$*</code> (see <a class="pxref" href="#Special-Parameters">Special Parameters</a>), and |
| <code class="code">"${<var class="var">name</var>[@]}"</code> and <code class="code">${<var class="var">name</var>[*]}</code> |
| (see <a class="pxref" href="#Arrays">Arrays</a>). |
| </p> |
| <p>After all expansions, <code class="code">quote removal</code> (see <a class="pxref" href="#Quote-Removal">Quote Removal</a>) |
| is performed. |
| </p> |
| <ul class="mini-toc"> |
| <li><a href="#Brace-Expansion" accesskey="1">Brace Expansion</a></li> |
| <li><a href="#Tilde-Expansion" accesskey="2">Tilde Expansion</a></li> |
| <li><a href="#Shell-Parameter-Expansion" accesskey="3">Shell Parameter Expansion</a></li> |
| <li><a href="#Command-Substitution" accesskey="4">Command Substitution</a></li> |
| <li><a href="#Arithmetic-Expansion" accesskey="5">Arithmetic Expansion</a></li> |
| <li><a href="#Process-Substitution" accesskey="6">Process Substitution</a></li> |
| <li><a href="#Word-Splitting" accesskey="7">Word Splitting</a></li> |
| <li><a href="#Filename-Expansion" accesskey="8">Filename Expansion</a></li> |
| <li><a href="#Quote-Removal" accesskey="9">Quote Removal</a></li> |
| </ul> |
| <hr> |
| <div class="subsection-level-extent" id="Brace-Expansion"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Tilde-Expansion" accesskey="n" rel="next">Tilde Expansion</a>, Up: <a href="#Shell-Expansions" accesskey="u" rel="up">Shell Expansions</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Brace-Expansion-1"><span>3.5.1 Brace Expansion<a class="copiable-link" href="#Brace-Expansion-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-brace-expansion"></a> |
| <a class="index-entry-id" id="index-expansion_002c-brace"></a> |
| |
| <p>Brace expansion is a mechanism by which arbitrary strings may be generated. |
| This mechanism is similar to |
| <em class="dfn">filename expansion</em> (see <a class="pxref" href="#Filename-Expansion">Filename Expansion</a>), |
| but the filenames generated need not exist. |
| Patterns to be brace expanded take the form of an optional <var class="var">preamble</var>, |
| followed by either a series of comma-separated strings or a sequence expression |
| between a pair of braces, |
| followed by an optional <var class="var">postscript</var>. |
| The preamble is prefixed to each string contained within the braces, and |
| the postscript is then appended to each resulting string, expanding left |
| to right. |
| </p> |
| <p>Brace expansions may be nested. |
| The results of each expanded string are not sorted; left to right order |
| is preserved. |
| For example, |
| </p><div class="example"> |
| <pre class="example-preformatted">bash$ echo a{d,c,b}e |
| ade ace abe |
| </pre></div> |
| |
| <p>A sequence expression takes the form <code class="code">{<var class="var">x</var>..<var class="var">y</var>[..<var class="var">incr</var>]}</code>, |
| where <var class="var">x</var> and <var class="var">y</var> are either integers or letters, |
| and <var class="var">incr</var>, an optional increment, is an integer. |
| When integers are supplied, the expression expands to each number between |
| <var class="var">x</var> and <var class="var">y</var>, inclusive. |
| Supplied integers may be prefixed with ‘<samp class="samp">0</samp>’ to force each term to have the |
| same width. |
| When either <var class="var">x</var> or <var class="var">y</var> begins with a zero, the shell |
| attempts to force all generated terms to contain the same number of digits, |
| zero-padding where necessary. |
| When letters are supplied, the expression expands to each character |
| lexicographically between <var class="var">x</var> and <var class="var">y</var>, inclusive, |
| using the default C locale. |
| Note that both <var class="var">x</var> and <var class="var">y</var> must be of the same type |
| (integer or letter). |
| When the increment is supplied, it is used as the difference between |
| each term. The default increment is 1 or -1 as appropriate. |
| </p> |
| <p>Brace expansion is performed before any other expansions, |
| and any characters special to other expansions are preserved |
| in the result. It is strictly textual. Bash |
| does not apply any syntactic interpretation to the context of the |
| expansion or the text between the braces. |
| </p> |
| <p>A correctly-formed brace expansion must contain unquoted opening |
| and closing braces, and at least one unquoted comma or a valid |
| sequence expression. |
| Any incorrectly formed brace expansion is left unchanged. |
| </p> |
| <p>A { or ‘<samp class="samp">,</samp>’ may be quoted with a backslash to prevent its |
| being considered part of a brace expression. |
| To avoid conflicts with parameter expansion, the string ‘<samp class="samp">${</samp>’ |
| is not considered eligible for brace expansion, |
| and inhibits brace expansion until the closing ‘<samp class="samp">}</samp>’. |
| </p> |
| <p>This construct is typically used as shorthand when the common |
| prefix of the strings to be generated is longer than in the |
| above example: |
| </p><div class="example"> |
| <pre class="example-preformatted">mkdir /usr/local/src/bash/{old,new,dist,bugs} |
| </pre></div> |
| <p>or |
| </p><div class="example"> |
| <pre class="example-preformatted">chown root /usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}} |
| </pre></div> |
| |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Tilde-Expansion"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Shell-Parameter-Expansion" accesskey="n" rel="next">Shell Parameter Expansion</a>, Previous: <a href="#Brace-Expansion" accesskey="p" rel="prev">Brace Expansion</a>, Up: <a href="#Shell-Expansions" accesskey="u" rel="up">Shell Expansions</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Tilde-Expansion-1"><span>3.5.2 Tilde Expansion<a class="copiable-link" href="#Tilde-Expansion-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-tilde-expansion"></a> |
| <a class="index-entry-id" id="index-expansion_002c-tilde"></a> |
| |
| <p>If a word begins with an unquoted tilde character (‘<samp class="samp">~</samp>’), all of the |
| characters up to the first unquoted slash (or all characters, |
| if there is no unquoted slash) are considered a <em class="dfn">tilde-prefix</em>. |
| If none of the characters in the tilde-prefix are quoted, the |
| characters in the tilde-prefix following the tilde are treated as a |
| possible <em class="dfn">login name</em>. |
| If this login name is the null string, the tilde is replaced with the |
| value of the <code class="env">HOME</code> shell variable. |
| If <code class="env">HOME</code> is unset, the home directory of the user executing the |
| shell is substituted instead. |
| Otherwise, the tilde-prefix is replaced with the home directory |
| associated with the specified login name. |
| </p> |
| <p>If the tilde-prefix is ‘<samp class="samp">~+</samp>’, the value of |
| the shell variable <code class="env">PWD</code> replaces the tilde-prefix. |
| If the tilde-prefix is ‘<samp class="samp">~-</samp>’, the value of the shell variable |
| <code class="env">OLDPWD</code>, if it is set, is substituted. |
| </p> |
| <p>If the characters following the tilde in the tilde-prefix consist of a |
| number <var class="var">N</var>, optionally prefixed by a ‘<samp class="samp">+</samp>’ or a ‘<samp class="samp">-</samp>’, |
| the tilde-prefix is replaced with the |
| corresponding element from the directory stack, as it would be displayed |
| by the <code class="code">dirs</code> builtin invoked with the characters following tilde |
| in the tilde-prefix as an argument (see <a class="pxref" href="#The-Directory-Stack">The Directory Stack</a>). |
| If the tilde-prefix, sans the tilde, consists of a number without a |
| leading ‘<samp class="samp">+</samp>’ or ‘<samp class="samp">-</samp>’, ‘<samp class="samp">+</samp>’ is assumed. |
| </p> |
| <p>If the login name is invalid, or the tilde expansion fails, the word is |
| left unchanged. |
| </p> |
| <p>Each variable assignment is checked for unquoted tilde-prefixes immediately |
| following a ‘<samp class="samp">:</samp>’ or the first ‘<samp class="samp">=</samp>’. |
| In these cases, tilde expansion is also performed. |
| Consequently, one may use filenames with tildes in assignments to |
| <code class="env">PATH</code>, <code class="env">MAILPATH</code>, and <code class="env">CDPATH</code>, |
| and the shell assigns the expanded value. |
| </p> |
| <p>The following table shows how Bash treats unquoted tilde-prefixes: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">~</code></dt> |
| <dd><p>The value of <code class="code">$HOME</code> |
| </p></dd> |
| <dt><code class="code">~/foo</code></dt> |
| <dd><p><samp class="file">$HOME/foo</samp> |
| </p> |
| </dd> |
| <dt><code class="code">~fred/foo</code></dt> |
| <dd><p>The subdirectory <code class="code">foo</code> of the home directory of the user |
| <code class="code">fred</code> |
| </p> |
| </dd> |
| <dt><code class="code">~+/foo</code></dt> |
| <dd><p><samp class="file">$PWD/foo</samp> |
| </p> |
| </dd> |
| <dt><code class="code">~-/foo</code></dt> |
| <dd><p><samp class="file">${OLDPWD-'~-'}/foo</samp> |
| </p> |
| </dd> |
| <dt><code class="code">~<var class="var">N</var></code></dt> |
| <dd><p>The string that would be displayed by ‘<samp class="samp">dirs +<var class="var">N</var></samp>’ |
| </p> |
| </dd> |
| <dt><code class="code">~+<var class="var">N</var></code></dt> |
| <dd><p>The string that would be displayed by ‘<samp class="samp">dirs +<var class="var">N</var></samp>’ |
| </p> |
| </dd> |
| <dt><code class="code">~-<var class="var">N</var></code></dt> |
| <dd><p>The string that would be displayed by ‘<samp class="samp">dirs -<var class="var">N</var></samp>’ |
| </p></dd> |
| </dl> |
| |
| <p>Bash also performs tilde expansion on words satisfying the conditions of |
| variable assignments (see <a class="pxref" href="#Shell-Parameters">Shell Parameters</a>) |
| when they appear as arguments to simple commands. |
| Bash does not do this, except for the declaration commands listed |
| above, when in <small class="sc">POSIX</small> mode. |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Shell-Parameter-Expansion"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Command-Substitution" accesskey="n" rel="next">Command Substitution</a>, Previous: <a href="#Tilde-Expansion" accesskey="p" rel="prev">Tilde Expansion</a>, Up: <a href="#Shell-Expansions" accesskey="u" rel="up">Shell Expansions</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Shell-Parameter-Expansion-1"><span>3.5.3 Shell Parameter Expansion<a class="copiable-link" href="#Shell-Parameter-Expansion-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-parameter-expansion"></a> |
| <a class="index-entry-id" id="index-expansion_002c-parameter"></a> |
| |
| <p>The ‘<samp class="samp">$</samp>’ character introduces parameter expansion, |
| command substitution, or arithmetic expansion. The parameter name |
| or symbol to be expanded may be enclosed in braces, which |
| are optional but serve to protect the variable to be expanded from |
| characters immediately following it which could be |
| interpreted as part of the name. |
| </p> |
| <p>When braces are used, the matching ending brace is the first ‘<samp class="samp">}</samp>’ |
| not escaped by a backslash or within a quoted string, and not within an |
| embedded arithmetic expansion, command substitution, or parameter |
| expansion. |
| </p> |
| <p>The basic form of parameter expansion is ${<var class="var">parameter</var>}. |
| The value of <var class="var">parameter</var> is substituted. |
| The <var class="var">parameter</var> is a shell parameter as described above |
| (see <a class="pxref" href="#Shell-Parameters">Shell Parameters</a>) or an array reference (see <a class="pxref" href="#Arrays">Arrays</a>). |
| The braces are required when <var class="var">parameter</var> |
| is a positional parameter with more than one digit, |
| or when <var class="var">parameter</var> is followed by a character that is not to be |
| interpreted as part of its name. |
| </p> |
| <p>If the first character of <var class="var">parameter</var> is an exclamation point (!), |
| and <var class="var">parameter</var> is not a nameref, |
| it introduces a level of indirection. |
| Bash uses the value formed by expanding the rest of |
| <var class="var">parameter</var> as the new <var class="var">parameter</var>; this is then |
| expanded and that value is used in the rest of the expansion, rather |
| than the expansion of the original <var class="var">parameter</var>. |
| This is known as <code class="code">indirect expansion</code>. |
| The value is subject to tilde expansion, |
| parameter expansion, command substitution, and arithmetic expansion. |
| If <var class="var">parameter</var> is a nameref, this expands to the name of the |
| variable referenced by <var class="var">parameter</var> instead of performing the |
| complete indirect expansion. |
| The exceptions to this are the expansions of ${!<var class="var">prefix</var>*} |
| and ${!<var class="var">name</var>[@]} |
| described below. |
| The exclamation point must immediately follow the left brace in order to |
| introduce indirection. |
| </p> |
| <p>In each of the cases below, <var class="var">word</var> is subject to tilde expansion, |
| parameter expansion, command substitution, and arithmetic expansion. |
| </p> |
| <p>When not performing substring expansion, using the form described |
| below (e.g., ‘<samp class="samp">:-</samp>’), Bash tests for a parameter that is unset or null. |
| Omitting the colon results in a test only for a parameter that is unset. |
| Put another way, if the colon is included, |
| the operator tests for both <var class="var">parameter</var>’s existence and that its value |
| is not null; if the colon is omitted, the operator tests only for existence. |
| </p> |
| <dl class="table"> |
| <dt><code class="code">${<var class="var">parameter</var>:−<var class="var">word</var>}</code></dt> |
| <dd><p>If <var class="var">parameter</var> is unset or null, the expansion of |
| <var class="var">word</var> is substituted. Otherwise, the value of |
| <var class="var">parameter</var> is substituted. |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">$ v=123 |
| $ echo ${v-unset} |
| 123 |
| </pre></div> |
| |
| </dd> |
| <dt><code class="code">${<var class="var">parameter</var>:=<var class="var">word</var>}</code></dt> |
| <dd><p>If <var class="var">parameter</var> |
| is unset or null, the expansion of <var class="var">word</var> |
| is assigned to <var class="var">parameter</var>. |
| The value of <var class="var">parameter</var> is then substituted. |
| Positional parameters and special parameters may not be assigned to |
| in this way. |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">$ var= |
| $ : ${var:=DEFAULT} |
| $ echo $var |
| DEFAULT |
| </pre></div> |
| |
| </dd> |
| <dt><code class="code">${<var class="var">parameter</var>:?<var class="var">word</var>}</code></dt> |
| <dd><p>If <var class="var">parameter</var> |
| is null or unset, the expansion of <var class="var">word</var> (or a message |
| to that effect if <var class="var">word</var> |
| is not present) is written to the standard error and the shell, if it |
| is not interactive, exits. Otherwise, the value of <var class="var">parameter</var> is |
| substituted. |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">$ var= |
| $ : ${var:?var is unset or null} |
| bash: var: var is unset or null |
| </pre></div> |
| |
| </dd> |
| <dt><code class="code">${<var class="var">parameter</var>:+<var class="var">word</var>}</code></dt> |
| <dd><p>If <var class="var">parameter</var> |
| is null or unset, nothing is substituted, otherwise the expansion of |
| <var class="var">word</var> is substituted. |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">$ var=123 |
| $ echo ${var:+var is set and not null} |
| var is set and not null |
| </pre></div> |
| |
| </dd> |
| <dt><code class="code">${<var class="var">parameter</var>:<var class="var">offset</var>}</code></dt> |
| <dt><code class="code">${<var class="var">parameter</var>:<var class="var">offset</var>:<var class="var">length</var>}</code></dt> |
| <dd><p>This is referred to as Substring Expansion. |
| It expands to up to <var class="var">length</var> characters of the value of <var class="var">parameter</var> |
| starting at the character specified by <var class="var">offset</var>. |
| If <var class="var">parameter</var> is ‘<samp class="samp">@</samp>’ or ‘<samp class="samp">*</samp>’, an indexed array subscripted by |
| ‘<samp class="samp">@</samp>’ or ‘<samp class="samp">*</samp>’, or an associative array name, the results differ as |
| described below. |
| If <var class="var">length</var> is omitted, it expands to the substring of the value of |
| <var class="var">parameter</var> starting at the character specified by <var class="var">offset</var> |
| and extending to the end of the value. |
| <var class="var">length</var> and <var class="var">offset</var> are arithmetic expressions |
| (see <a class="pxref" href="#Shell-Arithmetic">Shell Arithmetic</a>). |
| </p> |
| <p>If <var class="var">offset</var> evaluates to a number less than zero, the value |
| is used as an offset in characters |
| from the end of the value of <var class="var">parameter</var>. |
| If <var class="var">length</var> evaluates to a number less than zero, |
| it is interpreted as an offset in characters |
| from the end of the value of <var class="var">parameter</var> rather than |
| a number of characters, and the expansion is the characters between |
| <var class="var">offset</var> and that result. |
| Note that a negative offset must be separated from the colon by at least |
| one space to avoid being confused with the ‘<samp class="samp">:-</samp>’ expansion. |
| </p> |
| <p>Here are some examples illustrating substring expansion on parameters and |
| subscripted arrays: |
| </p> |
| <pre class="verbatim">$ string=01234567890abcdefgh |
| $ echo ${string:7} |
| 7890abcdefgh |
| $ echo ${string:7:0} |
| |
| $ echo ${string:7:2} |
| 78 |
| $ echo ${string:7:-2} |
| 7890abcdef |
| $ echo ${string: -7} |
| bcdefgh |
| $ echo ${string: -7:0} |
| |
| $ echo ${string: -7:2} |
| bc |
| $ echo ${string: -7:-2} |
| bcdef |
| $ set -- 01234567890abcdefgh |
| $ echo ${1:7} |
| 7890abcdefgh |
| $ echo ${1:7:0} |
| |
| $ echo ${1:7:2} |
| 78 |
| $ echo ${1:7:-2} |
| 7890abcdef |
| $ echo ${1: -7} |
| bcdefgh |
| $ echo ${1: -7:0} |
| |
| $ echo ${1: -7:2} |
| bc |
| $ echo ${1: -7:-2} |
| bcdef |
| $ array[0]=01234567890abcdefgh |
| $ echo ${array[0]:7} |
| 7890abcdefgh |
| $ echo ${array[0]:7:0} |
| |
| $ echo ${array[0]:7:2} |
| 78 |
| $ echo ${array[0]:7:-2} |
| 7890abcdef |
| $ echo ${array[0]: -7} |
| bcdefgh |
| $ echo ${array[0]: -7:0} |
| |
| $ echo ${array[0]: -7:2} |
| bc |
| $ echo ${array[0]: -7:-2} |
| bcdef |
| </pre> |
| <p>If <var class="var">parameter</var> is ‘<samp class="samp">@</samp>’ or ‘<samp class="samp">*</samp>’, the result is <var class="var">length</var> |
| positional parameters beginning at <var class="var">offset</var>. |
| A negative <var class="var">offset</var> is taken relative to one greater than the greatest |
| positional parameter, so an offset of -1 evaluates to the last positional |
| parameter. |
| It is an expansion error if <var class="var">length</var> evaluates to a number less than zero. |
| </p> |
| <p>The following examples illustrate substring expansion using positional |
| parameters: |
| </p> |
| <pre class="verbatim">$ set -- 1 2 3 4 5 6 7 8 9 0 a b c d e f g h |
| $ echo ${@:7} |
| 7 8 9 0 a b c d e f g h |
| $ echo ${@:7:0} |
| |
| $ echo ${@:7:2} |
| 7 8 |
| $ echo ${@:7:-2} |
| bash: -2: substring expression < 0 |
| $ echo ${@: -7:2} |
| b c |
| $ echo ${@:0} |
| ./bash 1 2 3 4 5 6 7 8 9 0 a b c d e f g h |
| $ echo ${@:0:2} |
| ./bash 1 |
| $ echo ${@: -7:0} |
| |
| </pre> |
| <p>If <var class="var">parameter</var> is an indexed array name subscripted |
| by ‘<samp class="samp">@</samp>’ or ‘<samp class="samp">*</samp>’, the result is the <var class="var">length</var> |
| members of the array beginning with <code class="code">${<var class="var">parameter</var>[<var class="var">offset</var>]}</code>. |
| A negative <var class="var">offset</var> is taken relative to one greater than the maximum |
| index of the specified array. |
| It is an expansion error if <var class="var">length</var> evaluates to a number less than zero. |
| </p> |
| <p>These examples show how you can use substring expansion with indexed |
| arrays: |
| </p> |
| <pre class="verbatim">$ array=(0 1 2 3 4 5 6 7 8 9 0 a b c d e f g h) |
| $ echo ${array[@]:7} |
| 7 8 9 0 a b c d e f g h |
| $ echo ${array[@]:7:2} |
| 7 8 |
| $ echo ${array[@]: -7:2} |
| b c |
| $ echo ${array[@]: -7:-2} |
| bash: -2: substring expression < 0 |
| $ echo ${array[@]:0} |
| 0 1 2 3 4 5 6 7 8 9 0 a b c d e f g h |
| $ echo ${array[@]:0:2} |
| 0 1 |
| $ echo ${array[@]: -7:0} |
| |
| </pre> |
| <p>Substring expansion applied to an associative array produces undefined |
| results. |
| </p> |
| <p>Substring indexing is zero-based unless the positional parameters |
| are used, in which case the indexing starts at 1 by default. |
| If <var class="var">offset</var> is 0, and the positional parameters are used, <code class="code">$0</code> is |
| prefixed to the list. |
| </p> |
| </dd> |
| <dt><code class="code">${!<var class="var">prefix</var>*}</code></dt> |
| <dt><code class="code">${!<var class="var">prefix</var>@}</code></dt> |
| <dd><p>Expands to the names of variables whose names begin with <var class="var">prefix</var>, |
| separated by the first character of the <code class="env">IFS</code> special variable. |
| When ‘<samp class="samp">@</samp>’ is used and the expansion appears within double quotes, each |
| variable name expands to a separate word. |
| </p> |
| </dd> |
| <dt><code class="code">${!<var class="var">name</var>[@]}</code></dt> |
| <dt><code class="code">${!<var class="var">name</var>[*]}</code></dt> |
| <dd><p>If <var class="var">name</var> is an array variable, expands to the list of array indices |
| (keys) assigned in <var class="var">name</var>. |
| If <var class="var">name</var> is not an array, expands to 0 if <var class="var">name</var> is set and null |
| otherwise. |
| When ‘<samp class="samp">@</samp>’ is used and the expansion appears within double quotes, each |
| key expands to a separate word. |
| </p> |
| </dd> |
| <dt><code class="code">${#<var class="var">parameter</var>}</code></dt> |
| <dd><p>The length in characters of the expanded value of <var class="var">parameter</var> is |
| substituted. |
| If <var class="var">parameter</var> is ‘<samp class="samp">*</samp>’ or ‘<samp class="samp">@</samp>’, the value substituted |
| is the number of positional parameters. |
| If <var class="var">parameter</var> is an array name subscripted by ‘<samp class="samp">*</samp>’ or ‘<samp class="samp">@</samp>’, |
| the value substituted is the number of elements in the array. |
| If <var class="var">parameter</var> |
| is an indexed array name subscripted by a negative number, that number is |
| interpreted as relative to one greater than the maximum index of |
| <var class="var">parameter</var>, so negative indices count back from the end of the |
| array, and an index of -1 references the last element. |
| </p> |
| </dd> |
| <dt><code class="code">${<var class="var">parameter</var>#<var class="var">word</var>}</code></dt> |
| <dt><code class="code">${<var class="var">parameter</var>##<var class="var">word</var>}</code></dt> |
| <dd><p>The <var class="var">word</var> |
| is expanded to produce a pattern and matched according to the rules |
| described below (see <a class="pxref" href="#Pattern-Matching">Pattern Matching</a>). If the pattern matches |
| the beginning of the expanded value of <var class="var">parameter</var>, |
| then the result of the expansion is the expanded value of <var class="var">parameter</var> |
| with the shortest matching pattern (the ‘<samp class="samp">#</samp>’ case) or the |
| longest matching pattern (the ‘<samp class="samp">##</samp>’ case) deleted. |
| If <var class="var">parameter</var> is ‘<samp class="samp">@</samp>’ or ‘<samp class="samp">*</samp>’, |
| the pattern removal operation is applied to each positional |
| parameter in turn, and the expansion is the resultant list. |
| If <var class="var">parameter</var> is an array variable subscripted with |
| ‘<samp class="samp">@</samp>’ or ‘<samp class="samp">*</samp>’, |
| the pattern removal operation is applied to each member of the |
| array in turn, and the expansion is the resultant list. |
| </p> |
| </dd> |
| <dt><code class="code">${<var class="var">parameter</var>%<var class="var">word</var>}</code></dt> |
| <dt><code class="code">${<var class="var">parameter</var>%%<var class="var">word</var>}</code></dt> |
| <dd><p>The <var class="var">word</var> |
| is expanded to produce a pattern and matched according to the rules |
| described below (see <a class="pxref" href="#Pattern-Matching">Pattern Matching</a>). |
| If the pattern matches a trailing portion of the expanded value of |
| <var class="var">parameter</var>, then the result of the expansion is the value of |
| <var class="var">parameter</var> with the shortest matching pattern (the ‘<samp class="samp">%</samp>’ case) |
| or the longest matching pattern (the ‘<samp class="samp">%%</samp>’ case) deleted. |
| If <var class="var">parameter</var> is ‘<samp class="samp">@</samp>’ or ‘<samp class="samp">*</samp>’, |
| the pattern removal operation is applied to each positional |
| parameter in turn, and the expansion is the resultant list. |
| If <var class="var">parameter</var> |
| is an array variable subscripted with ‘<samp class="samp">@</samp>’ or ‘<samp class="samp">*</samp>’, |
| the pattern removal operation is applied to each member of the |
| array in turn, and the expansion is the resultant list. |
| </p> |
| </dd> |
| <dt><code class="code">${<var class="var">parameter</var>/<var class="var">pattern</var>/<var class="var">string</var>}</code></dt> |
| <dt><code class="code">${<var class="var">parameter</var>//<var class="var">pattern</var>/<var class="var">string</var>}</code></dt> |
| <dt><code class="code">${<var class="var">parameter</var>/#<var class="var">pattern</var>/<var class="var">string</var>}</code></dt> |
| <dt><code class="code">${<var class="var">parameter</var>/%<var class="var">pattern</var>/<var class="var">string</var>}</code></dt> |
| <dd><p>The <var class="var">pattern</var> is expanded to produce a pattern just as in |
| filename expansion. |
| <var class="var">Parameter</var> is expanded and the longest match of <var class="var">pattern</var> |
| against its value is replaced with <var class="var">string</var>. |
| <var class="var">string</var> undergoes tilde expansion, parameter and variable expansion, |
| arithmetic expansion, command and process substitution, and quote removal. |
| The match is performed according to the rules described below |
| (see <a class="pxref" href="#Pattern-Matching">Pattern Matching</a>). |
| </p> |
| <p>In the first form above, only the first match is replaced. |
| If there are two slashes separating <var class="var">parameter</var> and <var class="var">pattern</var> |
| (the second form above), all matches of <var class="var">pattern</var> are |
| replaced with <var class="var">string</var>. |
| If <var class="var">pattern</var> is preceded by ‘<samp class="samp">#</samp>’ (the third form above), |
| it must match at the beginning of the expanded value of <var class="var">parameter</var>. |
| If <var class="var">pattern</var> is preceded by ‘<samp class="samp">%</samp>’ (the fourth form above), |
| it must match at the end of the expanded value of <var class="var">parameter</var>. |
| If the expansion of <var class="var">string</var> is null, |
| matches of <var class="var">pattern</var> are deleted. |
| If <var class="var">string</var> is null, |
| matches of <var class="var">pattern</var> are deleted |
| and the ‘<samp class="samp">/</samp>’ following <var class="var">pattern</var> may be omitted. |
| </p> |
| <p>If the <code class="code">patsub_replacement</code> shell option is enabled using <code class="code">shopt</code>, |
| any unquoted instances of ‘<samp class="samp">&</samp>’ in <var class="var">string</var> are replaced with the |
| matching portion of <var class="var">pattern</var>. |
| This is intended to duplicate a common <code class="code">sed</code> idiom. |
| </p> |
| <p>Quoting any part of <var class="var">string</var> inhibits replacement in the |
| expansion of the quoted portion, including replacement strings stored |
| in shell variables. |
| Backslash will escape ‘<samp class="samp">&</samp>’ in <var class="var">string</var>; the backslash is removed |
| in order to permit a literal ‘<samp class="samp">&</samp>’ in the replacement string. |
| Users should take care if <var class="var">string</var> is double-quoted to avoid |
| unwanted interactions between the backslash and double-quoting, since |
| backslash has special meaning within double quotes. |
| Pattern substitution performs the check for unquoted ‘<samp class="samp">&</samp>’ after |
| expanding <var class="var">string</var>, |
| so users should ensure to properly quote any occurrences of ‘<samp class="samp">&</samp>’ |
| they want to be taken literally in the replacement |
| and ensure any instances of ‘<samp class="samp">&</samp>’ they want to be replaced are unquoted. |
| </p> |
| <p>For instance, |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">var=abcdef |
| rep='& ' |
| echo ${var/abc/& } |
| echo "${var/abc/& }" |
| echo ${var/abc/$rep} |
| echo "${var/abc/$rep}" |
| </pre></div> |
| |
| <p>will display four lines of "abc def", while |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">var=abcdef |
| rep='& ' |
| echo ${var/abc/\& } |
| echo "${var/abc/\& }" |
| echo ${var/abc/"& "} |
| echo ${var/abc/"$rep"} |
| </pre></div> |
| |
| <p>will display four lines of "& def". |
| Like the pattern removal operators, double quotes surrounding the |
| replacement string quote the expanded characters, while double quotes |
| enclosing the entire parameter substitution do not, since |
| the expansion is performed in a |
| context that doesn’t take any enclosing double quotes into account. |
| </p> |
| <p>Since backslash can escape ‘<samp class="samp">&</samp>’, it can also escape a backslash in |
| the replacement string. |
| This means that ‘<samp class="samp">\\</samp>’ will insert a literal |
| backslash into the replacement, so these two <code class="code">echo</code> commands |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">var=abcdef |
| rep='\\&xyz' |
| echo ${var/abc/\\&xyz} |
| echo ${var/abc/$rep} |
| </pre></div> |
| |
| <p>will both output ‘<samp class="samp">\abcxyzdef</samp>’. |
| </p> |
| <p>It should rarely be necessary to enclose only <var class="var">string</var> in double |
| quotes. |
| </p> |
| <p>If the <code class="code">nocasematch</code> shell option |
| (see the description of <code class="code">shopt</code> in <a class="ref" href="#The-Shopt-Builtin">The Shopt Builtin</a>) |
| is enabled, the match is performed without regard to the case |
| of alphabetic characters. |
| If <var class="var">parameter</var> is ‘<samp class="samp">@</samp>’ or ‘<samp class="samp">*</samp>’, |
| the substitution operation is applied to each positional |
| parameter in turn, and the expansion is the resultant list. |
| If <var class="var">parameter</var> |
| is an array variable subscripted with ‘<samp class="samp">@</samp>’ or ‘<samp class="samp">*</samp>’, |
| the substitution operation is applied to each member of the |
| array in turn, and the expansion is the resultant list. |
| </p> |
| </dd> |
| <dt><code class="code">${<var class="var">parameter</var>^<var class="var">pattern</var>}</code></dt> |
| <dt><code class="code">${<var class="var">parameter</var>^^<var class="var">pattern</var>}</code></dt> |
| <dt><code class="code">${<var class="var">parameter</var>,<var class="var">pattern</var>}</code></dt> |
| <dt><code class="code">${<var class="var">parameter</var>,,<var class="var">pattern</var>}</code></dt> |
| <dd><p>This expansion modifies the case of alphabetic characters in <var class="var">parameter</var>. |
| The <var class="var">pattern</var> is expanded to produce a pattern just as in |
| filename expansion. |
| Each character in the expanded value of <var class="var">parameter</var> is tested against |
| <var class="var">pattern</var>, and, if it matches the pattern, its case is converted. |
| The pattern should not attempt to match more than one character. |
| </p> |
| <p>The ‘<samp class="samp">^</samp>’ operator converts lowercase letters matching <var class="var">pattern</var> |
| to uppercase; the ‘<samp class="samp">,</samp>’ operator converts matching uppercase letters |
| to lowercase. |
| The ‘<samp class="samp">^^</samp>’ and ‘<samp class="samp">,,</samp>’ expansions convert each matched character in the |
| expanded value; the ‘<samp class="samp">^</samp>’ and ‘<samp class="samp">,</samp>’ expansions match and convert only |
| the first character in the expanded value. |
| If <var class="var">pattern</var> is omitted, it is treated like a ‘<samp class="samp">?</samp>’, which matches |
| every character. |
| </p> |
| <p>If <var class="var">parameter</var> is ‘<samp class="samp">@</samp>’ or ‘<samp class="samp">*</samp>’, |
| the case modification operation is applied to each positional |
| parameter in turn, and the expansion is the resultant list. |
| If <var class="var">parameter</var> |
| is an array variable subscripted with ‘<samp class="samp">@</samp>’ or ‘<samp class="samp">*</samp>’, |
| the case modification operation is applied to each member of the |
| array in turn, and the expansion is the resultant list. |
| </p> |
| </dd> |
| <dt><code class="code">${<var class="var">parameter</var>@<var class="var">operator</var>}</code></dt> |
| <dd><p>The expansion is either a transformation of the value of <var class="var">parameter</var> |
| or information about <var class="var">parameter</var> itself, depending on the value of |
| <var class="var">operator</var>. Each <var class="var">operator</var> is a single letter: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">U</code></dt> |
| <dd><p>The expansion is a string that is the value of <var class="var">parameter</var> with lowercase |
| alphabetic characters converted to uppercase. |
| </p></dd> |
| <dt><code class="code">u</code></dt> |
| <dd><p>The expansion is a string that is the value of <var class="var">parameter</var> with the first |
| character converted to uppercase, if it is alphabetic. |
| </p></dd> |
| <dt><code class="code">L</code></dt> |
| <dd><p>The expansion is a string that is the value of <var class="var">parameter</var> with uppercase |
| alphabetic characters converted to lowercase. |
| </p></dd> |
| <dt><code class="code">Q</code></dt> |
| <dd><p>The expansion is a string that is the value of <var class="var">parameter</var> quoted in a |
| format that can be reused as input. |
| </p></dd> |
| <dt><code class="code">E</code></dt> |
| <dd><p>The expansion is a string that is the value of <var class="var">parameter</var> with backslash |
| escape sequences expanded as with the <code class="code">$'…'</code> quoting mechanism. |
| </p></dd> |
| <dt><code class="code">P</code></dt> |
| <dd><p>The expansion is a string that is the result of expanding the value of |
| <var class="var">parameter</var> as if it were a prompt string (see <a class="pxref" href="#Controlling-the-Prompt">Controlling the Prompt</a>). |
| </p></dd> |
| <dt><code class="code">A</code></dt> |
| <dd><p>The expansion is a string in the form of |
| an assignment statement or <code class="code">declare</code> command that, if |
| evaluated, will recreate <var class="var">parameter</var> with its attributes and value. |
| </p></dd> |
| <dt><code class="code">K</code></dt> |
| <dd><p>Produces a possibly-quoted version of the value of <var class="var">parameter</var>, |
| except that it prints the values of |
| indexed and associative arrays as a sequence of quoted key-value pairs |
| (see <a class="pxref" href="#Arrays">Arrays</a>). |
| </p></dd> |
| <dt><code class="code">a</code></dt> |
| <dd><p>The expansion is a string consisting of flag values representing |
| <var class="var">parameter</var>’s attributes. |
| </p></dd> |
| <dt><code class="code">k</code></dt> |
| <dd><p>Like the ‘<samp class="samp">K</samp>’ transformation, but expands the keys and values of |
| indexed and associative arrays to separate words after word splitting. |
| </p></dd> |
| </dl> |
| |
| <p>If <var class="var">parameter</var> is ‘<samp class="samp">@</samp>’ or ‘<samp class="samp">*</samp>’, |
| the operation is applied to each positional |
| parameter in turn, and the expansion is the resultant list. |
| If <var class="var">parameter</var> |
| is an array variable subscripted with ‘<samp class="samp">@</samp>’ or ‘<samp class="samp">*</samp>’, |
| the operation is applied to each member of the |
| array in turn, and the expansion is the resultant list. |
| </p> |
| <p>The result of the expansion is subject to word splitting and filename |
| expansion as described below. |
| </p></dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Command-Substitution"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Arithmetic-Expansion" accesskey="n" rel="next">Arithmetic Expansion</a>, Previous: <a href="#Shell-Parameter-Expansion" accesskey="p" rel="prev">Shell Parameter Expansion</a>, Up: <a href="#Shell-Expansions" accesskey="u" rel="up">Shell Expansions</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Command-Substitution-1"><span>3.5.4 Command Substitution<a class="copiable-link" href="#Command-Substitution-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-command-substitution"></a> |
| |
| <p>Command substitution allows the output of a command to replace |
| the command itself. |
| Command substitution occurs when a command is enclosed as follows: |
| </p><div class="example"> |
| <pre class="example-preformatted">$(<var class="var">command</var>) |
| </pre></div> |
| <p>or |
| </p><div class="example"> |
| <pre class="example-preformatted">`<var class="var">command</var>` |
| </pre></div> |
| |
| <p>Bash performs the expansion by executing <var class="var">command</var> in a subshell environment |
| and replacing the command substitution with the standard output of the |
| command, with any trailing newlines deleted. |
| Embedded newlines are not deleted, but they may be removed during |
| word splitting. |
| The command substitution <code class="code">$(cat <var class="var">file</var>)</code> can be |
| replaced by the equivalent but faster <code class="code">$(< <var class="var">file</var>)</code>. |
| </p> |
| <p>When the old-style backquote form of substitution is used, |
| backslash retains its literal meaning except when followed by |
| ‘<samp class="samp">$</samp>’, ‘<samp class="samp">`</samp>’, or ‘<samp class="samp">\</samp>’. |
| The first backquote not preceded by a backslash terminates the |
| command substitution. |
| When using the <code class="code">$(<var class="var">command</var>)</code> form, all characters between |
| the parentheses make up the command; none are treated specially. |
| </p> |
| <p>Command substitutions may be nested. To nest when using the backquoted |
| form, escape the inner backquotes with backslashes. |
| </p> |
| <p>If the substitution appears within double quotes, word splitting and |
| filename expansion are not performed on the results. |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Arithmetic-Expansion"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Process-Substitution" accesskey="n" rel="next">Process Substitution</a>, Previous: <a href="#Command-Substitution" accesskey="p" rel="prev">Command Substitution</a>, Up: <a href="#Shell-Expansions" accesskey="u" rel="up">Shell Expansions</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Arithmetic-Expansion-1"><span>3.5.5 Arithmetic Expansion<a class="copiable-link" href="#Arithmetic-Expansion-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-expansion_002c-arithmetic"></a> |
| <a class="index-entry-id" id="index-arithmetic-expansion"></a> |
| |
| <p>Arithmetic expansion allows the evaluation of an arithmetic expression |
| and the substitution of the result. The format for arithmetic expansion is: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">$(( <var class="var">expression</var> )) |
| </pre></div> |
| |
| <p>The <var class="var">expression</var> undergoes the same expansions |
| as if it were within double quotes, |
| but double quote characters in <var class="var">expression</var> are not treated specially |
| and are removed. |
| All tokens in the expression undergo parameter and variable expansion, |
| command substitution, and quote removal. |
| The result is treated as the arithmetic expression to be evaluated. |
| Arithmetic expansions may be nested. |
| </p> |
| <p>The evaluation is performed according to the rules listed below |
| (see <a class="pxref" href="#Shell-Arithmetic">Shell Arithmetic</a>). |
| If the expression is invalid, Bash prints a message indicating |
| failure to the standard error and no substitution occurs. |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Process-Substitution"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Word-Splitting" accesskey="n" rel="next">Word Splitting</a>, Previous: <a href="#Arithmetic-Expansion" accesskey="p" rel="prev">Arithmetic Expansion</a>, Up: <a href="#Shell-Expansions" accesskey="u" rel="up">Shell Expansions</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Process-Substitution-1"><span>3.5.6 Process Substitution<a class="copiable-link" href="#Process-Substitution-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-process-substitution"></a> |
| |
| <p>Process substitution allows a process’s input or output to be |
| referred to using a filename. |
| It takes the form of |
| </p><div class="example"> |
| <pre class="example-preformatted"><(<var class="var">list</var>) |
| </pre></div> |
| <p>or |
| </p><div class="example"> |
| <pre class="example-preformatted">>(<var class="var">list</var>) |
| </pre></div> |
| <p>The process <var class="var">list</var> is run asynchronously, and its input or output |
| appears as a filename. |
| This filename is |
| passed as an argument to the current command as the result of the |
| expansion. |
| If the <code class="code">>(<var class="var">list</var>)</code> form is used, writing to |
| the file will provide input for <var class="var">list</var>. If the |
| <code class="code"><(<var class="var">list</var>)</code> form is used, the file passed as an |
| argument should be read to obtain the output of <var class="var">list</var>. |
| Note that no space may appear between the <code class="code"><</code> or <code class="code">></code> |
| and the left parenthesis, otherwise the construct would be interpreted |
| as a redirection. |
| Process substitution is supported on systems that support named |
| pipes (<small class="sc">FIFO</small>s) or the <samp class="file">/dev/fd</samp> method of naming open files. |
| </p> |
| <p>When available, process substitution is performed simultaneously with |
| parameter and variable expansion, command substitution, and arithmetic |
| expansion. |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Word-Splitting"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Filename-Expansion" accesskey="n" rel="next">Filename Expansion</a>, Previous: <a href="#Process-Substitution" accesskey="p" rel="prev">Process Substitution</a>, Up: <a href="#Shell-Expansions" accesskey="u" rel="up">Shell Expansions</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Word-Splitting-1"><span>3.5.7 Word Splitting<a class="copiable-link" href="#Word-Splitting-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-word-splitting"></a> |
| |
| <p>The shell scans the results of parameter expansion, command substitution, |
| and arithmetic expansion that did not occur within double quotes for |
| word splitting. |
| </p> |
| <p>The shell treats each character of <code class="env">$IFS</code> as a delimiter, and splits |
| the results of the other expansions into words using these characters |
| as field terminators. |
| If <code class="env">IFS</code> is unset, or its value is exactly <code class="code"><space><tab><newline></code>, |
| the default, then sequences of |
| <code class="code"> <space></code>, <code class="code"><tab></code>, and <code class="code"><newline></code> |
| at the beginning and end of the results of the previous |
| expansions are ignored, and any sequence of <code class="env">IFS</code> |
| characters not at the beginning or end serves to delimit words. |
| If <code class="env">IFS</code> has a value other than the default, then sequences of |
| the whitespace characters <code class="code">space</code>, <code class="code">tab</code>, and <code class="code">newline</code> |
| are ignored at the beginning and end of the |
| word, as long as the whitespace character is in the |
| value of <code class="env">IFS</code> (an <code class="env">IFS</code> whitespace character). |
| Any character in <code class="env">IFS</code> that is not <code class="env">IFS</code> |
| whitespace, along with any adjacent <code class="env">IFS</code> |
| whitespace characters, delimits a field. A sequence of <code class="env">IFS</code> |
| whitespace characters is also treated as a delimiter. |
| If the value of <code class="env">IFS</code> is null, no word splitting occurs. |
| </p> |
| <p>Explicit null arguments (<code class="code">""</code> or <code class="code">''</code>) are retained |
| and passed to commands as empty strings. |
| Unquoted implicit null arguments, resulting from the expansion of |
| parameters that have no values, are removed. |
| If a parameter with no value is expanded within double quotes, a |
| null argument results and is retained |
| and passed to a command as an empty string. |
| When a quoted null argument appears as part of a word whose expansion is |
| non-null, the null argument is removed. |
| That is, the word |
| <code class="code">-d''</code> becomes <code class="code">-d</code> after word splitting and |
| null argument removal. |
| </p> |
| <p>Note that if no expansion occurs, no splitting |
| is performed. |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Filename-Expansion"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Quote-Removal" accesskey="n" rel="next">Quote Removal</a>, Previous: <a href="#Word-Splitting" accesskey="p" rel="prev">Word Splitting</a>, Up: <a href="#Shell-Expansions" accesskey="u" rel="up">Shell Expansions</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Filename-Expansion-1"><span>3.5.8 Filename Expansion<a class="copiable-link" href="#Filename-Expansion-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-expansion_002c-filename"></a> |
| <a class="index-entry-id" id="index-expansion_002c-pathname"></a> |
| <a class="index-entry-id" id="index-filename-expansion"></a> |
| <a class="index-entry-id" id="index-pathname-expansion"></a> |
| |
| <p>After word splitting, unless the <samp class="option">-f</samp> option has been set |
| (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>), Bash scans each word for the characters |
| ‘<samp class="samp">*</samp>’, ‘<samp class="samp">?</samp>’, and ‘<samp class="samp">[</samp>’. |
| If one of these characters appears, and is not quoted, then the word is |
| regarded as a <var class="var">pattern</var>, |
| and replaced with an alphabetically sorted list of |
| filenames matching the pattern (see <a class="pxref" href="#Pattern-Matching">Pattern Matching</a>). |
| If no matching filenames are found, |
| and the shell option <code class="code">nullglob</code> is disabled, the word is left |
| unchanged. |
| If the <code class="code">nullglob</code> option is set, and no matches are found, the word |
| is removed. |
| If the <code class="code">failglob</code> shell option is set, and no matches are found, |
| an error message is printed and the command is not executed. |
| If the shell option <code class="code">nocaseglob</code> is enabled, the match is performed |
| without regard to the case of alphabetic characters. |
| </p> |
| <p>When a pattern is used for filename expansion, the character ‘<samp class="samp">.</samp>’ |
| at the start of a filename or immediately following a slash |
| must be matched explicitly, unless the shell option <code class="code">dotglob</code> is set. |
| In order to match the filenames ‘<samp class="samp">.</samp>’ and ‘<samp class="samp">..</samp>’, |
| the pattern must begin with ‘<samp class="samp">.</samp>’ (for example, ‘<samp class="samp">.?</samp>’), |
| even if <code class="code">dotglob</code> is set. |
| If the <code class="code">globskipdots</code> shell option is enabled, the filenames |
| ‘<samp class="samp">.</samp>’ and ‘<samp class="samp">..</samp>’ are never matched, even if the pattern begins |
| with a ‘<samp class="samp">.</samp>’. |
| When not matching filenames, the ‘<samp class="samp">.</samp>’ character is not treated specially. |
| </p> |
| <p>When matching a filename, the slash character must always be |
| matched explicitly by a slash in the pattern, but in other matching |
| contexts it can be matched by a special pattern character as described |
| below (see <a class="pxref" href="#Pattern-Matching">Pattern Matching</a>). |
| </p> |
| <p>See the description of <code class="code">shopt</code> in <a class="ref" href="#The-Shopt-Builtin">The Shopt Builtin</a>, |
| for a description of the <code class="code">nocaseglob</code>, <code class="code">nullglob</code>, |
| <code class="code">globskipdots</code>, |
| <code class="code">failglob</code>, and <code class="code">dotglob</code> options. |
| </p> |
| <p>The <code class="env">GLOBIGNORE</code> |
| shell variable may be used to restrict the set of file names matching a |
| pattern. If <code class="env">GLOBIGNORE</code> |
| is set, each matching file name that also matches one of the patterns in |
| <code class="env">GLOBIGNORE</code> is removed from the list of matches. |
| If the <code class="code">nocaseglob</code> option is set, the matching against the patterns in |
| <code class="env">GLOBIGNORE</code> is performed without regard to case. |
| The filenames |
| <samp class="file">.</samp> and <samp class="file">..</samp> |
| are always ignored when <code class="env">GLOBIGNORE</code> |
| is set and not null. |
| However, setting <code class="env">GLOBIGNORE</code> to a non-null value has the effect of |
| enabling the <code class="code">dotglob</code> |
| shell option, so all other filenames beginning with a |
| ‘<samp class="samp">.</samp>’ will match. |
| To get the old behavior of ignoring filenames beginning with a |
| ‘<samp class="samp">.</samp>’, make ‘<samp class="samp">.*</samp>’ one of the patterns in <code class="env">GLOBIGNORE</code>. |
| The <code class="code">dotglob</code> option is disabled when <code class="env">GLOBIGNORE</code> |
| is unset. |
| </p> |
| <ul class="mini-toc"> |
| <li><a href="#Pattern-Matching" accesskey="1">Pattern Matching</a></li> |
| </ul> |
| <hr> |
| <div class="subsubsection-level-extent" id="Pattern-Matching"> |
| <div class="nav-panel"> |
| <p> |
| Up: <a href="#Filename-Expansion" accesskey="u" rel="up">Filename Expansion</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsubsection" id="Pattern-Matching-1"><span>3.5.8.1 Pattern Matching<a class="copiable-link" href="#Pattern-Matching-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-pattern-matching"></a> |
| <a class="index-entry-id" id="index-matching_002c-pattern"></a> |
| |
| <p>Any character that appears in a pattern, other than the special pattern |
| characters described below, matches itself. |
| The <small class="sc">NUL</small> character may not occur in a pattern. |
| A backslash escapes the following character; the |
| escaping backslash is discarded when matching. |
| The special pattern characters must be quoted if they are to be matched |
| literally. |
| </p> |
| <p>The special pattern characters have the following meanings: |
| </p><dl class="table"> |
| <dt><code class="code">*</code></dt> |
| <dd><p>Matches any string, including the null string. |
| When the <code class="code">globstar</code> shell option is enabled, and ‘<samp class="samp">*</samp>’ is used in |
| a filename expansion context, two adjacent ‘<samp class="samp">*</samp>’s used as a single |
| pattern will match all files and zero or more directories and |
| subdirectories. |
| If followed by a ‘<samp class="samp">/</samp>’, two adjacent ‘<samp class="samp">*</samp>’s will match only |
| directories and subdirectories. |
| </p></dd> |
| <dt><code class="code">?</code></dt> |
| <dd><p>Matches any single character. |
| </p></dd> |
| <dt><code class="code">[…]</code></dt> |
| <dd><p>Matches any one of the enclosed characters. A pair of characters |
| separated by a hyphen denotes a <var class="var">range expression</var>; |
| any character that falls between those two characters, inclusive, |
| using the current locale’s collating sequence and character set, |
| is matched. If the first character following the |
| ‘<samp class="samp">[</samp>’ is a ‘<samp class="samp">!</samp>’ or a ‘<samp class="samp">^</samp>’ |
| then any character not enclosed is matched. A ‘<samp class="samp">−</samp>’ |
| may be matched by including it as the first or last character |
| in the set. A ‘<samp class="samp">]</samp>’ may be matched by including it as the first |
| character in the set. |
| The sorting order of characters in range expressions, |
| and the characters included in the range, |
| are determined by |
| the current locale and the values of the |
| <code class="env">LC_COLLATE</code> and <code class="env">LC_ALL</code> shell variables, if set. |
| </p> |
| <p>For example, in the default C locale, ‘<samp class="samp">[a-dx-z]</samp>’ is equivalent to |
| ‘<samp class="samp">[abcdxyz]</samp>’. Many locales sort characters in dictionary order, and in |
| these locales ‘<samp class="samp">[a-dx-z]</samp>’ is typically not equivalent to ‘<samp class="samp">[abcdxyz]</samp>’; |
| it might be equivalent to ‘<samp class="samp">[aBbCcDdxYyZz]</samp>’, for example. To obtain |
| the traditional interpretation of ranges in bracket expressions, you can |
| force the use of the C locale by setting the <code class="env">LC_COLLATE</code> or |
| <code class="env">LC_ALL</code> environment variable to the value ‘<samp class="samp">C</samp>’, or enable the |
| <code class="code">globasciiranges</code> shell option. |
| </p> |
| <p>Within ‘<samp class="samp">[</samp>’ and ‘<samp class="samp">]</samp>’, <em class="dfn">character classes</em> can be specified |
| using the syntax |
| <code class="code">[:</code><var class="var">class</var><code class="code">:]</code>, where <var class="var">class</var> is one of the |
| following classes defined in the <small class="sc">POSIX</small> standard: |
| </p><div class="example"> |
| <pre class="example-preformatted">alnum alpha ascii blank cntrl digit graph lower |
| print punct space upper word xdigit |
| </pre></div> |
| <p>A character class matches any character belonging to that class. |
| The <code class="code">word</code> character class matches letters, digits, and the character |
| ‘<samp class="samp">_</samp>’. |
| </p> |
| <p>Within ‘<samp class="samp">[</samp>’ and ‘<samp class="samp">]</samp>’, an <em class="dfn">equivalence class</em> can be |
| specified using the syntax <code class="code">[=</code><var class="var">c</var><code class="code">=]</code>, which |
| matches all characters with the same collation weight (as defined |
| by the current locale) as the character <var class="var">c</var>. |
| </p> |
| <p>Within ‘<samp class="samp">[</samp>’ and ‘<samp class="samp">]</samp>’, the syntax <code class="code">[.</code><var class="var">symbol</var><code class="code">.]</code> |
| matches the collating symbol <var class="var">symbol</var>. |
| </p></dd> |
| </dl> |
| |
| <p>If the <code class="code">extglob</code> shell option is enabled using the <code class="code">shopt</code> |
| builtin, the shell recognizes several extended pattern matching operators. |
| In the following description, a <var class="var">pattern-list</var> is a list of one |
| or more patterns separated by a ‘<samp class="samp">|</samp>’. |
| When matching filenames, the <code class="code">dotglob</code> shell option determines |
| the set of filenames that are tested, as described above. |
| Composite patterns may be formed using one or more of the following |
| sub-patterns: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">?(<var class="var">pattern-list</var>)</code></dt> |
| <dd><p>Matches zero or one occurrence of the given patterns. |
| </p> |
| </dd> |
| <dt><code class="code">*(<var class="var">pattern-list</var>)</code></dt> |
| <dd><p>Matches zero or more occurrences of the given patterns. |
| </p> |
| </dd> |
| <dt><code class="code">+(<var class="var">pattern-list</var>)</code></dt> |
| <dd><p>Matches one or more occurrences of the given patterns. |
| </p> |
| </dd> |
| <dt><code class="code">@(<var class="var">pattern-list</var>)</code></dt> |
| <dd><p>Matches one of the given patterns. |
| </p> |
| </dd> |
| <dt><code class="code">!(<var class="var">pattern-list</var>)</code></dt> |
| <dd><p>Matches anything except one of the given patterns. |
| </p></dd> |
| </dl> |
| |
| <p>The <code class="code">extglob</code> option changes the behavior of the parser, since the |
| parentheses are normally treated as operators with syntactic meaning. |
| To ensure that extended matching patterns are parsed correctly, make sure |
| that <code class="code">extglob</code> is enabled before parsing constructs containing the |
| patterns, including shell functions and command substitutions. |
| </p> |
| <p>When matching filenames, the <code class="code">dotglob</code> shell option determines |
| the set of filenames that are tested: |
| when <code class="code">dotglob</code> is enabled, the set of filenames includes all files |
| beginning with ‘<samp class="samp">.</samp>’, but the filenames |
| ‘<samp class="samp">.</samp>’ and ‘<samp class="samp">..</samp>’ must be matched by a |
| pattern or sub-pattern that begins with a dot; |
| when it is disabled, the set does not |
| include any filenames beginning with “.” unless the pattern |
| or sub-pattern begins with a ‘<samp class="samp">.</samp>’. |
| As above, ‘<samp class="samp">.</samp>’ only has a special meaning when matching filenames. |
| </p> |
| <p>Complicated extended pattern matching against long strings is slow, |
| especially when the patterns contain alternations and the strings |
| contain multiple matches. |
| Using separate matches against shorter strings, or using arrays of |
| strings instead of a single long string, may be faster. |
| </p> |
| <hr> |
| </div> |
| </div> |
| <div class="subsection-level-extent" id="Quote-Removal"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Filename-Expansion" accesskey="p" rel="prev">Filename Expansion</a>, Up: <a href="#Shell-Expansions" accesskey="u" rel="up">Shell Expansions</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Quote-Removal-1"><span>3.5.9 Quote Removal<a class="copiable-link" href="#Quote-Removal-1"> ¶</a></span></h4> |
| |
| <p>After the preceding expansions, all unquoted occurrences of the |
| characters ‘<samp class="samp">\</samp>’, ‘<samp class="samp">'</samp>’, and ‘<samp class="samp">"</samp>’ that did not |
| result from one of the above expansions are removed. |
| </p> |
| <hr> |
| </div> |
| </div> |
| <div class="section-level-extent" id="Redirections"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Executing-Commands" accesskey="n" rel="next">Executing Commands</a>, Previous: <a href="#Shell-Expansions" accesskey="p" rel="prev">Shell Expansions</a>, Up: <a href="#Basic-Shell-Features" accesskey="u" rel="up">Basic Shell Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Redirections-1"><span>3.6 Redirections<a class="copiable-link" href="#Redirections-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-redirection"></a> |
| |
| <p>Before a command is executed, its input and output |
| may be <em class="dfn">redirected</em> |
| using a special notation interpreted by the shell. |
| <em class="dfn">Redirection</em> allows commands’ file handles to be |
| duplicated, opened, closed, |
| made to refer to different files, |
| and can change the files the command reads from and writes to. |
| Redirection may also be used to modify file handles in the |
| current shell execution environment. The following redirection |
| operators may precede or appear anywhere within a |
| simple command or may follow a command. |
| Redirections are processed in the order they appear, from |
| left to right. |
| </p> |
| <p>Each redirection that may be preceded by a file descriptor number |
| may instead be preceded by a word of the form {<var class="var">varname</var>}. |
| In this case, for each redirection operator except |
| >&- and <&-, the shell will allocate a file descriptor greater |
| than 10 and assign it to {<var class="var">varname</var>}. If >&- or <&- is preceded |
| by {<var class="var">varname</var>}, the value of <var class="var">varname</var> defines the file |
| descriptor to close. |
| If {<var class="var">varname</var>} is supplied, the redirection persists beyond |
| the scope of the command, allowing the shell programmer to manage |
| the file descriptor’s lifetime manually. |
| The <code class="code">varredir_close</code> shell option manages this behavior |
| (see <a class="pxref" href="#The-Shopt-Builtin">The Shopt Builtin</a>). |
| </p> |
| <p>In the following descriptions, if the file descriptor number is |
| omitted, and the first character of the redirection operator is |
| ‘<samp class="samp"><</samp>’, the redirection refers to the standard input (file |
| descriptor 0). If the first character of the redirection operator |
| is ‘<samp class="samp">></samp>’, the redirection refers to the standard output (file |
| descriptor 1). |
| </p> |
| <p>The word following the redirection operator in the following |
| descriptions, unless otherwise noted, is subjected to brace expansion, |
| tilde expansion, parameter expansion, command substitution, arithmetic |
| expansion, quote removal, filename expansion, and word splitting. |
| If it expands to more than one word, Bash reports an error. |
| </p> |
| <p>Note that the order of redirections is significant. For example, |
| the command |
| </p><div class="example"> |
| <pre class="example-preformatted">ls > <var class="var">dirlist</var> 2>&1 |
| </pre></div> |
| <p>directs both standard output (file descriptor 1) and standard error |
| (file descriptor 2) to the file <var class="var">dirlist</var>, while the command |
| </p><div class="example"> |
| <pre class="example-preformatted">ls 2>&1 > <var class="var">dirlist</var> |
| </pre></div> |
| <p>directs only the standard output to file <var class="var">dirlist</var>, |
| because the standard error was made a copy of the standard output |
| before the standard output was redirected to <var class="var">dirlist</var>. |
| </p> |
| <p>Bash handles several filenames specially when they are used in |
| redirections, as described in the following table. |
| If the operating system on which Bash is running provides these |
| special files, bash will use them; otherwise it will emulate them |
| internally with the behavior described below. |
| </p> |
| <dl class="table"> |
| <dt><code class="code">/dev/fd/<var class="var">fd</var></code></dt> |
| <dd><p>If <var class="var">fd</var> is a valid integer, file descriptor <var class="var">fd</var> is duplicated. |
| </p> |
| </dd> |
| <dt><code class="code">/dev/stdin</code></dt> |
| <dd><p>File descriptor 0 is duplicated. |
| </p> |
| </dd> |
| <dt><code class="code">/dev/stdout</code></dt> |
| <dd><p>File descriptor 1 is duplicated. |
| </p> |
| </dd> |
| <dt><code class="code">/dev/stderr</code></dt> |
| <dd><p>File descriptor 2 is duplicated. |
| </p> |
| </dd> |
| <dt><code class="code">/dev/tcp/<var class="var">host</var>/<var class="var">port</var></code></dt> |
| <dd><p>If <var class="var">host</var> is a valid hostname or Internet address, and <var class="var">port</var> |
| is an integer port number or service name, Bash attempts to open |
| the corresponding TCP socket. |
| </p> |
| </dd> |
| <dt><code class="code">/dev/udp/<var class="var">host</var>/<var class="var">port</var></code></dt> |
| <dd><p>If <var class="var">host</var> is a valid hostname or Internet address, and <var class="var">port</var> |
| is an integer port number or service name, Bash attempts to open |
| the corresponding UDP socket. |
| </p></dd> |
| </dl> |
| |
| <p>A failure to open or create a file causes the redirection to fail. |
| </p> |
| <p>Redirections using file descriptors greater than 9 should be used with |
| care, as they may conflict with file descriptors the shell uses |
| internally. |
| </p> |
| <ul class="mini-toc"> |
| <li><a href="#Redirecting-Input" accesskey="1">Redirecting Input</a></li> |
| <li><a href="#Redirecting-Output" accesskey="2">Redirecting Output</a></li> |
| <li><a href="#Appending-Redirected-Output" accesskey="3">Appending Redirected Output</a></li> |
| <li><a href="#Redirecting-Standard-Output-and-Standard-Error" accesskey="4">Redirecting Standard Output and Standard Error</a></li> |
| <li><a href="#Appending-Standard-Output-and-Standard-Error" accesskey="5">Appending Standard Output and Standard Error</a></li> |
| <li><a href="#Here-Documents" accesskey="6">Here Documents</a></li> |
| <li><a href="#Here-Strings" accesskey="7">Here Strings</a></li> |
| <li><a href="#Duplicating-File-Descriptors" accesskey="8">Duplicating File Descriptors</a></li> |
| <li><a href="#Moving-File-Descriptors" accesskey="9">Moving File Descriptors</a></li> |
| <li><a href="#Opening-File-Descriptors-for-Reading-and-Writing">Opening File Descriptors for Reading and Writing</a></li> |
| </ul> |
| <div class="subsection-level-extent" id="Redirecting-Input"> |
| <h4 class="subsection"><span>3.6.1 Redirecting Input<a class="copiable-link" href="#Redirecting-Input"> ¶</a></span></h4> |
| <p>Redirection of input causes the file whose name results from |
| the expansion of <var class="var">word</var> |
| to be opened for reading on file descriptor <code class="code">n</code>, |
| or the standard input (file descriptor 0) if <code class="code">n</code> |
| is not specified. |
| </p> |
| <p>The general format for redirecting input is: |
| </p><div class="example"> |
| <pre class="example-preformatted">[<var class="var">n</var>]<<var class="var">word</var> |
| </pre></div> |
| |
| </div> |
| <div class="subsection-level-extent" id="Redirecting-Output"> |
| <h4 class="subsection"><span>3.6.2 Redirecting Output<a class="copiable-link" href="#Redirecting-Output"> ¶</a></span></h4> |
| <p>Redirection of output causes the file whose name results from |
| the expansion of <var class="var">word</var> |
| to be opened for writing on file descriptor <var class="var">n</var>, |
| or the standard output (file descriptor 1) if <var class="var">n</var> |
| is not specified. If the file does not exist it is created; |
| if it does exist it is truncated to zero size. |
| </p> |
| <p>The general format for redirecting output is: |
| </p><div class="example"> |
| <pre class="example-preformatted">[<var class="var">n</var>]>[|]<var class="var">word</var> |
| </pre></div> |
| |
| <p>If the redirection operator is ‘<samp class="samp">></samp>’, and the <code class="code">noclobber</code> |
| option to the <code class="code">set</code> builtin has been enabled, the redirection |
| will fail if the file whose name results from the expansion of |
| <var class="var">word</var> exists and is a regular file. |
| If the redirection operator is ‘<samp class="samp">>|</samp>’, or the redirection operator is |
| ‘<samp class="samp">></samp>’ and the <code class="code">noclobber</code> option is not enabled, the redirection |
| is attempted even if the file named by <var class="var">word</var> exists. |
| </p> |
| </div> |
| <div class="subsection-level-extent" id="Appending-Redirected-Output"> |
| <h4 class="subsection"><span>3.6.3 Appending Redirected Output<a class="copiable-link" href="#Appending-Redirected-Output"> ¶</a></span></h4> |
| <p>Redirection of output in this fashion |
| causes the file whose name results from |
| the expansion of <var class="var">word</var> |
| to be opened for appending on file descriptor <var class="var">n</var>, |
| or the standard output (file descriptor 1) if <var class="var">n</var> |
| is not specified. If the file does not exist it is created. |
| </p> |
| <p>The general format for appending output is: |
| </p><div class="example"> |
| <pre class="example-preformatted">[<var class="var">n</var>]>><var class="var">word</var> |
| </pre></div> |
| |
| </div> |
| <div class="subsection-level-extent" id="Redirecting-Standard-Output-and-Standard-Error"> |
| <h4 class="subsection"><span>3.6.4 Redirecting Standard Output and Standard Error<a class="copiable-link" href="#Redirecting-Standard-Output-and-Standard-Error"> ¶</a></span></h4> |
| <p>This construct allows both the |
| standard output (file descriptor 1) and |
| the standard error output (file descriptor 2) |
| to be redirected to the file whose name is the |
| expansion of <var class="var">word</var>. |
| </p> |
| <p>There are two formats for redirecting standard output and |
| standard error: |
| </p><div class="example"> |
| <pre class="example-preformatted">&><var class="var">word</var> |
| </pre></div> |
| <p>and |
| </p><div class="example"> |
| <pre class="example-preformatted">>&<var class="var">word</var> |
| </pre></div> |
| <p>Of the two forms, the first is preferred. |
| This is semantically equivalent to |
| </p><div class="example"> |
| <pre class="example-preformatted">><var class="var">word</var> 2>&1 |
| </pre></div> |
| <p>When using the second form, <var class="var">word</var> may not expand to a number or |
| ‘<samp class="samp">-</samp>’. If it does, other redirection operators apply |
| (see Duplicating File Descriptors below) for compatibility reasons. |
| </p> |
| </div> |
| <div class="subsection-level-extent" id="Appending-Standard-Output-and-Standard-Error"> |
| <h4 class="subsection"><span>3.6.5 Appending Standard Output and Standard Error<a class="copiable-link" href="#Appending-Standard-Output-and-Standard-Error"> ¶</a></span></h4> |
| <p>This construct allows both the |
| standard output (file descriptor 1) and |
| the standard error output (file descriptor 2) |
| to be appended to the file whose name is the |
| expansion of <var class="var">word</var>. |
| </p> |
| <p>The format for appending standard output and standard error is: |
| </p><div class="example"> |
| <pre class="example-preformatted">&>><var class="var">word</var> |
| </pre></div> |
| <p>This is semantically equivalent to |
| </p><div class="example"> |
| <pre class="example-preformatted">>><var class="var">word</var> 2>&1 |
| </pre></div> |
| <p>(see Duplicating File Descriptors below). |
| </p> |
| </div> |
| <div class="subsection-level-extent" id="Here-Documents"> |
| <h4 class="subsection"><span>3.6.6 Here Documents<a class="copiable-link" href="#Here-Documents"> ¶</a></span></h4> |
| <p>This type of redirection instructs the shell to read input from the |
| current source until a line containing only <var class="var">word</var> |
| (with no trailing blanks) is seen. All of |
| the lines read up to that point are then used as the standard |
| input (or file descriptor <var class="var">n</var> if <var class="var">n</var> is specified) for a command. |
| </p> |
| <p>The format of here-documents is: |
| </p><div class="example"> |
| <pre class="example-preformatted">[<var class="var">n</var>]<<[−]<var class="var">word</var> |
| <var class="var">here-document</var> |
| <var class="var">delimiter</var> |
| </pre></div> |
| |
| <p>No parameter and variable expansion, command substitution, |
| arithmetic expansion, or filename expansion is performed on |
| <var class="var">word</var>. If any part of <var class="var">word</var> is quoted, the |
| <var class="var">delimiter</var> is the result of quote removal on <var class="var">word</var>, |
| and the lines in the here-document are not expanded. |
| If <var class="var">word</var> is unquoted, |
| all lines of the here-document are subjected to |
| parameter expansion, command substitution, and arithmetic expansion, |
| the character sequence <code class="code">\newline</code> is ignored, and ‘<samp class="samp">\</samp>’ |
| must be used to quote the characters |
| ‘<samp class="samp">\</samp>’, ‘<samp class="samp">$</samp>’, and ‘<samp class="samp">`</samp>’. |
| </p> |
| <p>If the redirection operator is ‘<samp class="samp"><<-</samp>’, |
| then all leading tab characters are stripped from input lines and the |
| line containing <var class="var">delimiter</var>. |
| This allows here-documents within shell scripts to be indented in a |
| natural fashion. |
| </p> |
| </div> |
| <div class="subsection-level-extent" id="Here-Strings"> |
| <h4 class="subsection"><span>3.6.7 Here Strings<a class="copiable-link" href="#Here-Strings"> ¶</a></span></h4> |
| <p>A variant of here documents, the format is: |
| </p><div class="example"> |
| <pre class="example-preformatted">[<var class="var">n</var>]<<< <var class="var">word</var> |
| </pre></div> |
| |
| <p>The <var class="var">word</var> undergoes |
| tilde expansion, parameter and variable expansion, |
| command substitution, arithmetic expansion, and quote removal. |
| Filename expansion and word splitting are not performed. |
| The result is supplied as a single string, |
| with a newline appended, |
| to the command on its |
| standard input (or file descriptor <var class="var">n</var> if <var class="var">n</var> is specified). |
| </p> |
| </div> |
| <div class="subsection-level-extent" id="Duplicating-File-Descriptors"> |
| <h4 class="subsection"><span>3.6.8 Duplicating File Descriptors<a class="copiable-link" href="#Duplicating-File-Descriptors"> ¶</a></span></h4> |
| <p>The redirection operator |
| </p><div class="example"> |
| <pre class="example-preformatted">[<var class="var">n</var>]<&<var class="var">word</var> |
| </pre></div> |
| <p>is used to duplicate input file descriptors. |
| If <var class="var">word</var> |
| expands to one or more digits, the file descriptor denoted by <var class="var">n</var> |
| is made to be a copy of that file descriptor. |
| If the digits in <var class="var">word</var> do not specify a file descriptor open for |
| input, a redirection error occurs. |
| If <var class="var">word</var> |
| evaluates to ‘<samp class="samp">-</samp>’, file descriptor <var class="var">n</var> is closed. |
| If <var class="var">n</var> is not specified, the standard input (file descriptor 0) is used. |
| </p> |
| <p>The operator |
| </p><div class="example"> |
| <pre class="example-preformatted">[<var class="var">n</var>]>&<var class="var">word</var> |
| </pre></div> |
| <p>is used similarly to duplicate output file descriptors. If |
| <var class="var">n</var> is not specified, the standard output (file descriptor 1) is used. |
| If the digits in <var class="var">word</var> do not specify a file descriptor open for |
| output, a redirection error occurs. |
| If <var class="var">word</var> |
| evaluates to ‘<samp class="samp">-</samp>’, file descriptor <var class="var">n</var> is closed. |
| As a special case, if <var class="var">n</var> is omitted, and <var class="var">word</var> does not |
| expand to one or more digits or ‘<samp class="samp">-</samp>’, the standard output and standard |
| error are redirected as described previously. |
| </p> |
| </div> |
| <div class="subsection-level-extent" id="Moving-File-Descriptors"> |
| <h4 class="subsection"><span>3.6.9 Moving File Descriptors<a class="copiable-link" href="#Moving-File-Descriptors"> ¶</a></span></h4> |
| <p>The redirection operator |
| </p><div class="example"> |
| <pre class="example-preformatted">[<var class="var">n</var>]<&<var class="var">digit</var>- |
| </pre></div> |
| <p>moves the file descriptor <var class="var">digit</var> to file descriptor <var class="var">n</var>, |
| or the standard input (file descriptor 0) if <var class="var">n</var> is not specified. |
| <var class="var">digit</var> is closed after being duplicated to <var class="var">n</var>. |
| </p> |
| <p>Similarly, the redirection operator |
| </p><div class="example"> |
| <pre class="example-preformatted">[<var class="var">n</var>]>&<var class="var">digit</var>- |
| </pre></div> |
| <p>moves the file descriptor <var class="var">digit</var> to file descriptor <var class="var">n</var>, |
| or the standard output (file descriptor 1) if <var class="var">n</var> is not specified. |
| </p> |
| </div> |
| <div class="subsection-level-extent" id="Opening-File-Descriptors-for-Reading-and-Writing"> |
| <h4 class="subsection"><span>3.6.10 Opening File Descriptors for Reading and Writing<a class="copiable-link" href="#Opening-File-Descriptors-for-Reading-and-Writing"> ¶</a></span></h4> |
| <p>The redirection operator |
| </p><div class="example"> |
| <pre class="example-preformatted">[<var class="var">n</var>]<><var class="var">word</var> |
| </pre></div> |
| <p>causes the file whose name is the expansion of <var class="var">word</var> |
| to be opened for both reading and writing on file descriptor |
| <var class="var">n</var>, or on file descriptor 0 if <var class="var">n</var> |
| is not specified. If the file does not exist, it is created. |
| </p> |
| <hr> |
| </div> |
| </div> |
| <div class="section-level-extent" id="Executing-Commands"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Shell-Scripts" accesskey="n" rel="next">Shell Scripts</a>, Previous: <a href="#Redirections" accesskey="p" rel="prev">Redirections</a>, Up: <a href="#Basic-Shell-Features" accesskey="u" rel="up">Basic Shell Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Executing-Commands-1"><span>3.7 Executing Commands<a class="copiable-link" href="#Executing-Commands-1"> ¶</a></span></h3> |
| |
| |
| <ul class="mini-toc"> |
| <li><a href="#Simple-Command-Expansion" accesskey="1">Simple Command Expansion</a></li> |
| <li><a href="#Command-Search-and-Execution" accesskey="2">Command Search and Execution</a></li> |
| <li><a href="#Command-Execution-Environment" accesskey="3">Command Execution Environment</a></li> |
| <li><a href="#Environment" accesskey="4">Environment</a></li> |
| <li><a href="#Exit-Status" accesskey="5">Exit Status</a></li> |
| <li><a href="#Signals" accesskey="6">Signals</a></li> |
| </ul> |
| <hr> |
| <div class="subsection-level-extent" id="Simple-Command-Expansion"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Command-Search-and-Execution" accesskey="n" rel="next">Command Search and Execution</a>, Up: <a href="#Executing-Commands" accesskey="u" rel="up">Executing Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Simple-Command-Expansion-1"><span>3.7.1 Simple Command Expansion<a class="copiable-link" href="#Simple-Command-Expansion-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-command-expansion"></a> |
| |
| <p>When a simple command is executed, the shell performs the following |
| expansions, assignments, and redirections, from left to right, in |
| the following order. |
| </p> |
| <ol class="enumerate"> |
| <li> The words that the parser has marked as variable assignments (those |
| preceding the command name) and redirections are saved for later |
| processing. |
| |
| </li><li> The words that are not variable assignments or redirections are |
| expanded (see <a class="pxref" href="#Shell-Expansions">Shell Expansions</a>). |
| If any words remain after expansion, the first word |
| is taken to be the name of the command and the remaining words are |
| the arguments. |
| |
| </li><li> Redirections are performed as described above (see <a class="pxref" href="#Redirections">Redirections</a>). |
| |
| </li><li> The text after the ‘<samp class="samp">=</samp>’ in each variable assignment undergoes tilde |
| expansion, parameter expansion, command substitution, arithmetic expansion, |
| and quote removal before being assigned to the variable. |
| </li></ol> |
| |
| <p>If no command name results, the variable assignments affect the current |
| shell environment. |
| In the case of such a command (one that consists only of assignment |
| statements and redirections), assignment statements are performed before |
| redirections. |
| Otherwise, the variables are added to the environment |
| of the executed command and do not affect the current shell environment. |
| If any of the assignments attempts to assign a value to a readonly variable, |
| an error occurs, and the command exits with a non-zero status. |
| </p> |
| <p>If no command name results, redirections are performed, but do not |
| affect the current shell environment. A redirection error causes the |
| command to exit with a non-zero status. |
| </p> |
| <p>If there is a command name left after expansion, execution proceeds as |
| described below. Otherwise, the command exits. If one of the expansions |
| contained a command substitution, the exit status of the command is |
| the exit status of the last command substitution performed. If there |
| were no command substitutions, the command exits with a status of zero. |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Command-Search-and-Execution"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Command-Execution-Environment" accesskey="n" rel="next">Command Execution Environment</a>, Previous: <a href="#Simple-Command-Expansion" accesskey="p" rel="prev">Simple Command Expansion</a>, Up: <a href="#Executing-Commands" accesskey="u" rel="up">Executing Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Command-Search-and-Execution-1"><span>3.7.2 Command Search and Execution<a class="copiable-link" href="#Command-Search-and-Execution-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-command-execution"></a> |
| <a class="index-entry-id" id="index-command-search"></a> |
| |
| <p>After a command has been split into words, if it results in a |
| simple command and an optional list of arguments, the following |
| actions are taken. |
| </p> |
| <ol class="enumerate"> |
| <li> If the command name contains no slashes, the shell attempts to |
| locate it. If there exists a shell function by that name, that |
| function is invoked as described in <a class="ref" href="#Shell-Functions">Shell Functions</a>. |
| |
| </li><li> If the name does not match a function, the shell searches for |
| it in the list of shell builtins. If a match is found, that |
| builtin is invoked. |
| |
| </li><li> If the name is neither a shell function nor a builtin, |
| and contains no slashes, Bash searches each element of |
| <code class="env">$PATH</code> for a directory containing an executable file |
| by that name. Bash uses a hash table to remember the full |
| pathnames of executable files to avoid multiple <code class="env">PATH</code> searches |
| (see the description of <code class="code">hash</code> in <a class="ref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>). |
| A full search of the directories in <code class="env">$PATH</code> |
| is performed only if the command is not found in the hash table. |
| If the search is unsuccessful, the shell searches for a defined shell |
| function named <code class="code">command_not_found_handle</code>. |
| If that function exists, it is invoked in a separate execution environment |
| with the original command and |
| the original command’s arguments as its arguments, and the function’s |
| exit status becomes the exit status of that subshell. |
| If that function is not defined, the shell prints an error |
| message and returns an exit status of 127. |
| |
| </li><li> If the search is successful, or if the command name contains |
| one or more slashes, the shell executes the named program in |
| a separate execution environment. |
| Argument 0 is set to the name given, and the remaining arguments |
| to the command are set to the arguments supplied, if any. |
| |
| </li><li> If this execution fails because the file is not in executable |
| format, and the file is not a directory, it is assumed to be a |
| <em class="dfn">shell script</em> and the shell executes it as described in |
| <a class="ref" href="#Shell-Scripts">Shell Scripts</a>. |
| |
| </li><li> If the command was not begun asynchronously, the shell waits for |
| the command to complete and collects its exit status. |
| |
| </li></ol> |
| |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Command-Execution-Environment"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Environment" accesskey="n" rel="next">Environment</a>, Previous: <a href="#Command-Search-and-Execution" accesskey="p" rel="prev">Command Search and Execution</a>, Up: <a href="#Executing-Commands" accesskey="u" rel="up">Executing Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Command-Execution-Environment-1"><span>3.7.3 Command Execution Environment<a class="copiable-link" href="#Command-Execution-Environment-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-execution-environment"></a> |
| |
| <p>The shell has an <em class="dfn">execution environment</em>, which consists of the |
| following: |
| </p> |
| <ul class="itemize mark-bullet"> |
| <li>open files inherited by the shell at invocation, as modified by |
| redirections supplied to the <code class="code">exec</code> builtin |
| |
| </li><li>the current working directory as set by <code class="code">cd</code>, <code class="code">pushd</code>, or |
| <code class="code">popd</code>, or inherited by the shell at invocation |
| |
| </li><li>the file creation mode mask as set by <code class="code">umask</code> or inherited from |
| the shell’s parent |
| |
| </li><li>current traps set by <code class="code">trap</code> |
| |
| </li><li>shell parameters that are set by variable assignment or with <code class="code">set</code> |
| or inherited from the shell’s parent in the environment |
| |
| </li><li>shell functions defined during execution or inherited from the shell’s |
| parent in the environment |
| |
| </li><li>options enabled at invocation (either by default or with command-line |
| arguments) or by <code class="code">set</code> |
| |
| </li><li>options enabled by <code class="code">shopt</code> (see <a class="pxref" href="#The-Shopt-Builtin">The Shopt Builtin</a>) |
| |
| </li><li>shell aliases defined with <code class="code">alias</code> (see <a class="pxref" href="#Aliases">Aliases</a>) |
| |
| </li><li>various process <small class="sc">ID</small>s, including those of background jobs |
| (see <a class="pxref" href="#Lists">Lists of Commands</a>), the value of <code class="code">$$</code>, and the value of |
| <code class="env">$PPID</code> |
| |
| </li></ul> |
| |
| <p>When a simple command other than a builtin or shell function |
| is to be executed, it |
| is invoked in a separate execution environment that consists of |
| the following. Unless otherwise noted, the values are inherited |
| from the shell. |
| </p> |
| <ul class="itemize mark-bullet"> |
| <li>the shell’s open files, plus any modifications and additions specified |
| by redirections to the command |
| |
| </li><li>the current working directory |
| |
| </li><li>the file creation mode mask |
| |
| </li><li>shell variables and functions marked for export, along with variables |
| exported for the command, passed in the environment (see <a class="pxref" href="#Environment">Environment</a>) |
| |
| </li><li>traps caught by the shell are reset to the values inherited from the |
| shell’s parent, and traps ignored by the shell are ignored |
| |
| </li></ul> |
| |
| <p>A command invoked in this separate environment cannot affect the |
| shell’s execution environment. |
| </p> |
| <p>A <em class="dfn">subshell</em> is a copy of the shell process. |
| </p> |
| <p>Command substitution, commands grouped with parentheses, |
| and asynchronous commands are invoked in a |
| subshell environment that is a duplicate of the shell environment, |
| except that traps caught by the shell are reset to the values |
| that the shell inherited from its parent at invocation. Builtin |
| commands that are invoked as part of a pipeline are also executed |
| in a subshell environment. Changes made to the subshell environment |
| cannot affect the shell’s execution environment. |
| </p> |
| <p>Subshells spawned to execute command substitutions inherit the value of |
| the <samp class="option">-e</samp> option from the parent shell. When not in <small class="sc">POSIX</small> mode, |
| Bash clears the <samp class="option">-e</samp> option in such subshells. |
| </p> |
| <p>If a command is followed by a ‘<samp class="samp">&</samp>’ and job control is not active, the |
| default standard input for the command is the empty file <samp class="file">/dev/null</samp>. |
| Otherwise, the invoked command inherits the file descriptors of the calling |
| shell as modified by redirections. |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Environment"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Exit-Status" accesskey="n" rel="next">Exit Status</a>, Previous: <a href="#Command-Execution-Environment" accesskey="p" rel="prev">Command Execution Environment</a>, Up: <a href="#Executing-Commands" accesskey="u" rel="up">Executing Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Environment-1"><span>3.7.4 Environment<a class="copiable-link" href="#Environment-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-environment"></a> |
| |
| <p>When a program is invoked it is given an array of strings |
| called the <em class="dfn">environment</em>. |
| This is a list of name-value pairs, of the form <code class="code">name=value</code>. |
| </p> |
| <p>Bash provides several ways to manipulate the environment. |
| On invocation, the shell scans its own environment and |
| creates a parameter for each name found, automatically marking |
| it for <code class="code">export</code> |
| to child processes. Executed commands inherit the environment. |
| The <code class="code">export</code> and ‘<samp class="samp">declare -x</samp>’ |
| commands allow parameters and functions to be added to and |
| deleted from the environment. If the value of a parameter |
| in the environment is modified, the new value becomes part |
| of the environment, replacing the old. The environment |
| inherited by any executed command consists of the shell’s |
| initial environment, whose values may be modified in the shell, |
| less any pairs removed by the <code class="code">unset</code> and ‘<samp class="samp">export -n</samp>’ |
| commands, plus any additions via the <code class="code">export</code> and |
| ‘<samp class="samp">declare -x</samp>’ commands. |
| </p> |
| <p>The environment for any simple command |
| or function may be augmented temporarily by prefixing it with |
| parameter assignments, as described in <a class="ref" href="#Shell-Parameters">Shell Parameters</a>. |
| These assignment statements affect only the environment seen |
| by that command. |
| </p> |
| <p>If the <samp class="option">-k</samp> option is set (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>), then all |
| parameter assignments are placed in the environment for a command, |
| not just those that precede the command name. |
| </p> |
| <p>When Bash invokes an external command, the variable ‘<samp class="samp">$_</samp>’ |
| is set to the full pathname of the command and passed to that |
| command in its environment. |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Exit-Status"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Signals" accesskey="n" rel="next">Signals</a>, Previous: <a href="#Environment" accesskey="p" rel="prev">Environment</a>, Up: <a href="#Executing-Commands" accesskey="u" rel="up">Executing Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Exit-Status-1"><span>3.7.5 Exit Status<a class="copiable-link" href="#Exit-Status-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-exit-status-1"></a> |
| |
| <p>The exit status of an executed command is the value returned by the |
| <code class="code">waitpid</code> system call or equivalent function. Exit statuses |
| fall between 0 and 255, though, as explained below, the shell may |
| use values above 125 specially. Exit statuses from shell builtins and |
| compound commands are also limited to this range. Under certain |
| circumstances, the shell will use special values to indicate specific |
| failure modes. |
| </p> |
| <p>For the shell’s purposes, a command which exits with a |
| zero exit status has succeeded. |
| A non-zero exit status indicates failure. |
| This seemingly counter-intuitive scheme is used so there |
| is one well-defined way to indicate success and a variety of |
| ways to indicate various failure modes. |
| When a command terminates on a fatal signal whose number is <var class="var">N</var>, |
| Bash uses the value 128+<var class="var">N</var> as the exit status. |
| </p> |
| <p>If a command is not found, the child process created to |
| execute it returns a status of 127. If a command is found |
| but is not executable, the return status is 126. |
| </p> |
| <p>If a command fails because of an error during expansion or redirection, |
| the exit status is greater than zero. |
| </p> |
| <p>The exit status is used by the Bash conditional commands |
| (see <a class="pxref" href="#Conditional-Constructs">Conditional Constructs</a>) and some of the list |
| constructs (see <a class="pxref" href="#Lists">Lists of Commands</a>). |
| </p> |
| <p>All of the Bash builtins return an exit status of zero if they succeed |
| and a non-zero status on failure, so they may be used by the |
| conditional and list constructs. |
| All builtins return an exit status of 2 to indicate incorrect usage, |
| generally invalid options or missing arguments. |
| </p> |
| <p>The exit status of the last command is available in the special |
| parameter $? (see <a class="pxref" href="#Special-Parameters">Special Parameters</a>). |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Signals"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Exit-Status" accesskey="p" rel="prev">Exit Status</a>, Up: <a href="#Executing-Commands" accesskey="u" rel="up">Executing Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Signals-1"><span>3.7.6 Signals<a class="copiable-link" href="#Signals-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-signal-handling"></a> |
| |
| <p>When Bash is interactive, in the absence of any traps, it ignores |
| <code class="code">SIGTERM</code> (so that ‘<samp class="samp">kill 0</samp>’ does not kill an interactive shell), |
| and <code class="code">SIGINT</code> |
| is caught and handled (so that the <code class="code">wait</code> builtin is interruptible). |
| When Bash receives a <code class="code">SIGINT</code>, it breaks out of any executing loops. |
| In all cases, Bash ignores <code class="code">SIGQUIT</code>. |
| If job control is in effect (see <a class="pxref" href="#Job-Control">Job Control</a>), Bash |
| ignores <code class="code">SIGTTIN</code>, <code class="code">SIGTTOU</code>, and <code class="code">SIGTSTP</code>. |
| </p> |
| <p>Non-builtin commands started by Bash have signal handlers set to the |
| values inherited by the shell from its parent. |
| When job control is not in effect, asynchronous commands |
| ignore <code class="code">SIGINT</code> and <code class="code">SIGQUIT</code> in addition to these inherited |
| handlers. |
| Commands run as a result of |
| command substitution ignore the keyboard-generated job control signals |
| <code class="code">SIGTTIN</code>, <code class="code">SIGTTOU</code>, and <code class="code">SIGTSTP</code>. |
| </p> |
| <p>The shell exits by default upon receipt of a <code class="code">SIGHUP</code>. |
| Before exiting, an interactive shell resends the <code class="code">SIGHUP</code> to |
| all jobs, running or stopped. |
| Stopped jobs are sent <code class="code">SIGCONT</code> to ensure that they receive |
| the <code class="code">SIGHUP</code>. |
| To prevent the shell from sending the <code class="code">SIGHUP</code> signal to a |
| particular job, it should be removed |
| from the jobs table with the <code class="code">disown</code> |
| builtin (see <a class="pxref" href="#Job-Control-Builtins">Job Control Builtins</a>) or marked |
| to not receive <code class="code">SIGHUP</code> using <code class="code">disown -h</code>. |
| </p> |
| <p>If the <code class="code">huponexit</code> shell option has been set with <code class="code">shopt</code> |
| (see <a class="pxref" href="#The-Shopt-Builtin">The Shopt Builtin</a>), Bash sends a <code class="code">SIGHUP</code> to all jobs when |
| an interactive login shell exits. |
| </p> |
| <p>If Bash is waiting for a command to complete and receives a signal |
| for which a trap has been set, the trap will not be executed until |
| the command completes. |
| When Bash is waiting for an asynchronous |
| command via the <code class="code">wait</code> builtin, the reception of a signal for |
| which a trap has been set will cause the <code class="code">wait</code> builtin to return |
| immediately with an exit status greater than 128, immediately after |
| which the trap is executed. |
| </p> |
| <p>When job control is not enabled, and Bash is waiting for a foreground |
| command to complete, the shell receives keyboard-generated signals |
| such as <code class="code">SIGINT</code> (usually generated by ‘<samp class="samp">^C</samp>’) that users |
| commonly intend to send to that command. |
| This happens because the shell and the command are in the same process |
| group as the terminal, and ‘<samp class="samp">^C</samp>’ sends <code class="code">SIGINT</code> to all processes |
| in that process group. |
| See <a class="ref" href="#Job-Control">Job Control</a>, for a more in-depth discussion of process groups. |
| </p> |
| <p>When Bash is running without job control enabled and receives <code class="code">SIGINT</code> |
| while waiting for a foreground command, it waits until that foreground |
| command terminates and then decides what to do about the <code class="code">SIGINT</code>: |
| </p> |
| <ol class="enumerate"> |
| <li> If the command terminates due to the <code class="code">SIGINT</code>, Bash concludes |
| that the user meant to end the entire script, and acts on the |
| <code class="code">SIGINT</code> (e.g., by running a <code class="code">SIGINT</code> trap or exiting itself); |
| |
| </li><li> If the pipeline does not terminate due to <code class="code">SIGINT</code>, the program |
| handled the <code class="code">SIGINT</code> itself and did not treat it as a fatal signal. |
| In that case, Bash does not treat <code class="code">SIGINT</code> as a fatal signal, |
| either, instead assuming that the <code class="code">SIGINT</code> was used as part of the |
| program’s normal operation (e.g., <code class="command">emacs</code> uses it to abort editing |
| commands) or deliberately discarded. However, Bash will run any |
| trap set on <code class="code">SIGINT</code>, as it does with any other trapped signal it |
| receives while it is waiting for the foreground command to |
| complete, for compatibility. |
| </li></ol> |
| |
| <hr> |
| </div> |
| </div> |
| <div class="section-level-extent" id="Shell-Scripts"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Executing-Commands" accesskey="p" rel="prev">Executing Commands</a>, Up: <a href="#Basic-Shell-Features" accesskey="u" rel="up">Basic Shell Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Shell-Scripts-1"><span>3.8 Shell Scripts<a class="copiable-link" href="#Shell-Scripts-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-shell-script"></a> |
| |
| <p>A shell script is a text file containing shell commands. When such |
| a file is used as the first non-option argument when invoking Bash, |
| and neither the <samp class="option">-c</samp> nor <samp class="option">-s</samp> option is supplied |
| (see <a class="pxref" href="#Invoking-Bash">Invoking Bash</a>), |
| Bash reads and executes commands from the file, then exits. This |
| mode of operation creates a non-interactive shell. The shell first |
| searches for the file in the current directory, and looks in the |
| directories in <code class="env">$PATH</code> if not found there. |
| </p> |
| <p>When Bash runs |
| a shell script, it sets the special parameter <code class="code">0</code> to the name |
| of the file, rather than the name of the shell, and the positional |
| parameters are set to the remaining arguments, if any are given. |
| If no additional arguments are supplied, the positional parameters |
| are unset. |
| </p> |
| <p>A shell script may be made executable by using the <code class="code">chmod</code> command |
| to turn on the execute bit. When Bash finds such a file while |
| searching the <code class="env">$PATH</code> for a command, it creates a |
| new instance of itself |
| to execute it. |
| In other words, executing |
| </p><div class="example"> |
| <pre class="example-preformatted">filename <var class="var">arguments</var> |
| </pre></div> |
| <p>is equivalent to executing |
| </p><div class="example"> |
| <pre class="example-preformatted">bash filename <var class="var">arguments</var> |
| </pre></div> |
| |
| <p>if <code class="code">filename</code> is an executable shell script. |
| This subshell reinitializes itself, so that the effect is as if a |
| new shell had been invoked to interpret the script, with the |
| exception that the locations of commands remembered by the parent |
| (see the description of <code class="code">hash</code> in <a class="ref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>) |
| are retained by the child. |
| </p> |
| <p>Most versions of Unix make this a part of the operating system’s command |
| execution mechanism. If the first line of a script begins with |
| the two characters ‘<samp class="samp">#!</samp>’, the remainder of the line specifies |
| an interpreter for the program and, depending on the operating system, one |
| or more optional arguments for that interpreter. |
| Thus, you can specify Bash, <code class="code">awk</code>, Perl, or some other |
| interpreter and write the rest of the script file in that language. |
| </p> |
| <p>The arguments to the interpreter |
| consist of one or more optional arguments following the interpreter |
| name on the first line of the script file, followed by the name of |
| the script file, followed by the rest of the arguments supplied to the |
| script. |
| The details of how the interpreter line is split into an interpreter name |
| and a set of arguments vary across systems. |
| Bash will perform this action on operating systems that do not handle it |
| themselves. |
| Note that some older versions of Unix limit the interpreter |
| name and a single argument to a maximum of 32 characters, so it’s not |
| portable to assume that using more than one argument will work. |
| </p> |
| <p>Bash scripts often begin with <code class="code">#! /bin/bash</code> (assuming that |
| Bash has been installed in <samp class="file">/bin</samp>), since this ensures that |
| Bash will be used to interpret the script, even if it is executed |
| under another shell. It’s a common idiom to use <code class="code">env</code> to find |
| <code class="code">bash</code> even if it’s been installed in another directory: |
| <code class="code">#!/usr/bin/env bash</code> will find the first occurrence of <code class="code">bash</code> |
| in <code class="env">$PATH</code>. |
| </p> |
| <hr> |
| </div> |
| </div> |
| <div class="chapter-level-extent" id="Shell-Builtin-Commands"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Shell-Variables" accesskey="n" rel="next">Shell Variables</a>, Previous: <a href="#Basic-Shell-Features" accesskey="p" rel="prev">Basic Shell Features</a>, Up: <a href="#Top" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h2 class="chapter" id="Shell-Builtin-Commands-1"><span>4 Shell Builtin Commands<a class="copiable-link" href="#Shell-Builtin-Commands-1"> ¶</a></span></h2> |
| |
| |
| <p>Builtin commands are contained within the shell itself. |
| When the name of a builtin command is used as the first word of |
| a simple command (see <a class="pxref" href="#Simple-Commands">Simple Commands</a>), the shell executes |
| the command directly, without invoking another program. |
| Builtin commands are necessary to implement functionality impossible |
| or inconvenient to obtain with separate utilities. |
| </p> |
| <p>This section briefly describes the builtins which Bash inherits from |
| the Bourne Shell, as well as the builtin commands which are unique |
| to or have been extended in Bash. |
| </p> |
| <p>Several builtin commands are described in other chapters: builtin |
| commands which provide the Bash interface to the job control |
| facilities (see <a class="pxref" href="#Job-Control-Builtins">Job Control Builtins</a>), the directory stack |
| (see <a class="pxref" href="#Directory-Stack-Builtins">Directory Stack Builtins</a>), the command history |
| (see <a class="pxref" href="#Bash-History-Builtins">Bash History Builtins</a>), and the programmable completion |
| facilities (see <a class="pxref" href="#Programmable-Completion-Builtins">Programmable Completion Builtins</a>). |
| </p> |
| <p>Many of the builtins have been extended by <small class="sc">POSIX</small> or Bash. |
| </p> |
| <p>Unless otherwise noted, each builtin command documented as accepting |
| options preceded by ‘<samp class="samp">-</samp>’ accepts ‘<samp class="samp">--</samp>’ |
| to signify the end of the options. |
| The <code class="code">:</code>, <code class="code">true</code>, <code class="code">false</code>, and <code class="code">test</code>/<code class="code">[</code> |
| builtins do not accept options and do not treat ‘<samp class="samp">--</samp>’ specially. |
| The <code class="code">exit</code>, <code class="code">logout</code>, <code class="code">return</code>, |
| <code class="code">break</code>, <code class="code">continue</code>, <code class="code">let</code>, |
| and <code class="code">shift</code> builtins accept and process arguments beginning |
| with ‘<samp class="samp">-</samp>’ without requiring ‘<samp class="samp">--</samp>’. |
| Other builtins that accept arguments but are not specified as accepting |
| options interpret arguments beginning with ‘<samp class="samp">-</samp>’ as invalid options and |
| require ‘<samp class="samp">--</samp>’ to prevent this interpretation. |
| </p> |
| <ul class="mini-toc"> |
| <li><a href="#Bourne-Shell-Builtins" accesskey="1">Bourne Shell Builtins</a></li> |
| <li><a href="#Bash-Builtins" accesskey="2">Bash Builtin Commands</a></li> |
| <li><a href="#Modifying-Shell-Behavior" accesskey="3">Modifying Shell Behavior</a></li> |
| <li><a href="#Special-Builtins" accesskey="4">Special Builtins</a></li> |
| </ul> |
| <hr> |
| <div class="section-level-extent" id="Bourne-Shell-Builtins"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Bash-Builtins" accesskey="n" rel="next">Bash Builtin Commands</a>, Up: <a href="#Shell-Builtin-Commands" accesskey="u" rel="up">Shell Builtin Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Bourne-Shell-Builtins-1"><span>4.1 Bourne Shell Builtins<a class="copiable-link" href="#Bourne-Shell-Builtins-1"> ¶</a></span></h3> |
| |
| <p>The following shell builtin commands are inherited from the Bourne Shell. |
| These commands are implemented as specified by the <small class="sc">POSIX</small> standard. |
| </p> |
| <dl class="table"> |
| <dt><a id="index-_003a"></a><span><code class="code">: <span class="r">(a colon)</span></code><a class="copiable-link" href="#index-_003a"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">: [<var class="var">arguments</var>] |
| </pre></div> |
| |
| <p>Do nothing beyond expanding <var class="var">arguments</var> and performing redirections. |
| The return status is zero. |
| </p> |
| </dd> |
| <dt><a id="index-_002e"></a><span><code class="code">. <span class="r">(a period)</span></code><a class="copiable-link" href="#index-_002e"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">. <var class="var">filename</var> [<var class="var">arguments</var>] |
| </pre></div> |
| |
| <p>Read and execute commands from the <var class="var">filename</var> argument in the |
| current shell context. If <var class="var">filename</var> does not contain a slash, |
| the <code class="env">PATH</code> variable is used to find <var class="var">filename</var>, |
| but <var class="var">filename</var> does not need to be executable. |
| When Bash is not in <small class="sc">POSIX</small> mode, it searches the current directory |
| if <var class="var">filename</var> is not found in <code class="env">$PATH</code>. |
| If any <var class="var">arguments</var> are supplied, they become the positional |
| parameters when <var class="var">filename</var> is executed. Otherwise the positional |
| parameters are unchanged. |
| If the <samp class="option">-T</samp> option is enabled, <code class="code">.</code> inherits any trap on |
| <code class="code">DEBUG</code>; if it is not, any <code class="code">DEBUG</code> trap string is saved and |
| restored around the call to <code class="code">.</code>, and <code class="code">.</code> unsets the |
| <code class="code">DEBUG</code> trap while it executes. |
| If <samp class="option">-T</samp> is not set, and the sourced file changes |
| the <code class="code">DEBUG</code> trap, the new value is retained when <code class="code">.</code> completes. |
| The return status is the exit status of the last command executed, or |
| zero if no commands are executed. If <var class="var">filename</var> is not found, or |
| cannot be read, the return status is non-zero. |
| This builtin is equivalent to <code class="code">source</code>. |
| </p> |
| </dd> |
| <dt><a id="index-break"></a><span><code class="code">break</code><a class="copiable-link" href="#index-break"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">break [<var class="var">n</var>] |
| </pre></div> |
| |
| <p>Exit from a <code class="code">for</code>, <code class="code">while</code>, <code class="code">until</code>, or <code class="code">select</code> loop. |
| If <var class="var">n</var> is supplied, the <var class="var">n</var>th enclosing loop is exited. |
| <var class="var">n</var> must be greater than or equal to 1. |
| The return status is zero unless <var class="var">n</var> is not greater than or equal to 1. |
| </p> |
| </dd> |
| <dt><a id="index-cd"></a><span><code class="code">cd</code><a class="copiable-link" href="#index-cd"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">cd [-L|[-P [-e]] [-@] [<var class="var">directory</var>] |
| </pre></div> |
| |
| <p>Change the current working directory to <var class="var">directory</var>. |
| If <var class="var">directory</var> is not supplied, the value of the <code class="env">HOME</code> |
| shell variable is used. |
| If the shell variable |
| <code class="env">CDPATH</code> exists, it is used as a search path: |
| each directory name in <code class="env">CDPATH</code> is searched for |
| <var class="var">directory</var>, with alternative directory names in <code class="env">CDPATH</code> |
| separated by a colon (‘<samp class="samp">:</samp>’). |
| If <var class="var">directory</var> begins with a slash, <code class="env">CDPATH</code> is not used. |
| </p> |
| <p>The <samp class="option">-P</samp> option means to not follow symbolic links: symbolic links |
| are resolved while <code class="code">cd</code> is traversing <var class="var">directory</var> and before |
| processing an instance of ‘<samp class="samp">..</samp>’ in <var class="var">directory</var>. |
| </p> |
| <p>By default, or when the <samp class="option">-L</samp> option is supplied, symbolic links |
| in <var class="var">directory</var> are resolved after <code class="code">cd</code> processes an instance |
| of ‘<samp class="samp">..</samp>’ in <var class="var">directory</var>. |
| </p> |
| <p>If ‘<samp class="samp">..</samp>’ appears in <var class="var">directory</var>, it is processed by removing the |
| immediately preceding pathname component, back to a slash or the beginning |
| of <var class="var">directory</var>. |
| </p> |
| <p>If the <samp class="option">-e</samp> option is supplied with <samp class="option">-P</samp> |
| and the current working directory cannot be successfully determined |
| after a successful directory change, <code class="code">cd</code> will return an unsuccessful |
| status. |
| </p> |
| <p>On systems that support it, the <samp class="option">-@</samp> option presents the extended |
| attributes associated with a file as a directory. |
| </p> |
| <p>If <var class="var">directory</var> is ‘<samp class="samp">-</samp>’, it is converted to <code class="env">$OLDPWD</code> |
| before the directory change is attempted. |
| </p> |
| <p>If a non-empty directory name from <code class="env">CDPATH</code> is used, or if |
| ‘<samp class="samp">-</samp>’ is the first argument, and the directory change is |
| successful, the absolute pathname of the new working directory is |
| written to the standard output. |
| </p> |
| <p>If the directory change is successful, <code class="code">cd</code> sets the value of the |
| <code class="env">PWD</code> environment variable to the new directory name, and sets the |
| <code class="env">OLDPWD</code> environment variable to the value of the current working |
| directory before the change. |
| </p> |
| <p>The return status is zero if the directory is successfully changed, |
| non-zero otherwise. |
| </p> |
| </dd> |
| <dt><a id="index-continue"></a><span><code class="code">continue</code><a class="copiable-link" href="#index-continue"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">continue [<var class="var">n</var>] |
| </pre></div> |
| |
| <p>Resume the next iteration of an enclosing <code class="code">for</code>, <code class="code">while</code>, |
| <code class="code">until</code>, or <code class="code">select</code> loop. |
| If <var class="var">n</var> is supplied, the execution of the <var class="var">n</var>th enclosing loop |
| is resumed. |
| <var class="var">n</var> must be greater than or equal to 1. |
| The return status is zero unless <var class="var">n</var> is not greater than or equal to 1. |
| </p> |
| </dd> |
| <dt><a id="index-eval"></a><span><code class="code">eval</code><a class="copiable-link" href="#index-eval"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">eval [<var class="var">arguments</var>] |
| </pre></div> |
| |
| <p>The arguments are concatenated together into a single command, which is |
| then read and executed, and its exit status returned as the exit status |
| of <code class="code">eval</code>. |
| If there are no arguments or only empty arguments, the return status is |
| zero. |
| </p> |
| </dd> |
| <dt><a id="index-exec"></a><span><code class="code">exec</code><a class="copiable-link" href="#index-exec"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">exec [-cl] [-a <var class="var">name</var>] [<var class="var">command</var> [<var class="var">arguments</var>]] |
| </pre></div> |
| |
| <p>If <var class="var">command</var> |
| is supplied, it replaces the shell without creating a new process. |
| If the <samp class="option">-l</samp> option is supplied, the shell places a dash at the |
| beginning of the zeroth argument passed to <var class="var">command</var>. |
| This is what the <code class="code">login</code> program does. |
| The <samp class="option">-c</samp> option causes <var class="var">command</var> to be executed with an empty |
| environment. |
| If <samp class="option">-a</samp> is supplied, the shell passes <var class="var">name</var> as the zeroth |
| argument to <var class="var">command</var>. |
| If <var class="var">command</var> |
| cannot be executed for some reason, a non-interactive shell exits, |
| unless the <code class="code">execfail</code> shell option |
| is enabled. In that case, it returns failure. |
| An interactive shell returns failure if the file cannot be executed. |
| A subshell exits unconditionally if <code class="code">exec</code> fails. |
| If no <var class="var">command</var> is specified, redirections may be used to affect |
| the current shell environment. If there are no redirection errors, the |
| return status is zero; otherwise the return status is non-zero. |
| </p> |
| </dd> |
| <dt><a id="index-exit"></a><span><code class="code">exit</code><a class="copiable-link" href="#index-exit"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">exit [<var class="var">n</var>] |
| </pre></div> |
| |
| <p>Exit the shell, returning a status of <var class="var">n</var> to the shell’s parent. |
| If <var class="var">n</var> is omitted, the exit status is that of the last command executed. |
| Any trap on <code class="code">EXIT</code> is executed before the shell terminates. |
| </p> |
| </dd> |
| <dt><a id="index-export"></a><span><code class="code">export</code><a class="copiable-link" href="#index-export"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">export [-fn] [-p] [<var class="var">name</var>[=<var class="var">value</var>]] |
| </pre></div> |
| |
| <p>Mark each <var class="var">name</var> to be passed to child processes |
| in the environment. If the <samp class="option">-f</samp> option is supplied, the <var class="var">name</var>s |
| refer to shell functions; otherwise the names refer to shell variables. |
| The <samp class="option">-n</samp> option means to no longer mark each <var class="var">name</var> for export. |
| If no <var class="var">name</var>s are supplied, or if the <samp class="option">-p</samp> option is given, a |
| list of names of all exported variables is displayed. |
| The <samp class="option">-p</samp> option displays output in a form that may be reused as input. |
| If a variable name is followed by =<var class="var">value</var>, the value of |
| the variable is set to <var class="var">value</var>. |
| </p> |
| <p>The return status is zero unless an invalid option is supplied, one of |
| the names is not a valid shell variable name, or <samp class="option">-f</samp> is supplied |
| with a name that is not a shell function. |
| </p> |
| </dd> |
| <dt><a id="index-getopts"></a><span><code class="code">getopts</code><a class="copiable-link" href="#index-getopts"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">getopts <var class="var">optstring</var> <var class="var">name</var> [<var class="var">arg</var> ...] |
| </pre></div> |
| |
| <p><code class="code">getopts</code> is used by shell scripts to parse positional parameters. |
| <var class="var">optstring</var> contains the option characters to be recognized; if a |
| character is followed by a colon, the option is expected to have an |
| argument, which should be separated from it by whitespace. |
| The colon (‘<samp class="samp">:</samp>’) and question mark (‘<samp class="samp">?</samp>’) may not be |
| used as option characters. |
| Each time it is invoked, <code class="code">getopts</code> |
| places the next option in the shell variable <var class="var">name</var>, initializing |
| <var class="var">name</var> if it does not exist, |
| and the index of the next argument to be processed into the |
| variable <code class="env">OPTIND</code>. |
| <code class="env">OPTIND</code> is initialized to 1 each time the shell or a shell script |
| is invoked. |
| When an option requires an argument, |
| <code class="code">getopts</code> places that argument into the variable <code class="env">OPTARG</code>. |
| The shell does not reset <code class="env">OPTIND</code> automatically; it must be manually |
| reset between multiple calls to <code class="code">getopts</code> within the same shell |
| invocation if a new set of parameters is to be used. |
| </p> |
| <p>When the end of options is encountered, <code class="code">getopts</code> exits with a |
| return value greater than zero. |
| <code class="env">OPTIND</code> is set to the index of the first non-option argument, |
| and <var class="var">name</var> is set to ‘<samp class="samp">?</samp>’. |
| </p> |
| <p><code class="code">getopts</code> |
| normally parses the positional parameters, but if more arguments are |
| supplied as <var class="var">arg</var> values, <code class="code">getopts</code> parses those instead. |
| </p> |
| <p><code class="code">getopts</code> can report errors in two ways. If the first character of |
| <var class="var">optstring</var> is a colon, <var class="var">silent</var> |
| error reporting is used. In normal operation, diagnostic messages |
| are printed when invalid options or missing option arguments are |
| encountered. |
| If the variable <code class="env">OPTERR</code> |
| is set to 0, no error messages will be displayed, even if the first |
| character of <code class="code">optstring</code> is not a colon. |
| </p> |
| <p>If an invalid option is seen, |
| <code class="code">getopts</code> places ‘<samp class="samp">?</samp>’ into <var class="var">name</var> and, if not silent, |
| prints an error message and unsets <code class="env">OPTARG</code>. |
| If <code class="code">getopts</code> is silent, the option character found is placed in |
| <code class="env">OPTARG</code> and no diagnostic message is printed. |
| </p> |
| <p>If a required argument is not found, and <code class="code">getopts</code> |
| is not silent, a question mark (‘<samp class="samp">?</samp>’) is placed in <var class="var">name</var>, |
| <code class="code">OPTARG</code> is unset, and a diagnostic message is printed. |
| If <code class="code">getopts</code> is silent, then a colon (‘<samp class="samp">:</samp>’) is placed in |
| <var class="var">name</var> and <code class="env">OPTARG</code> is set to the option character found. |
| </p> |
| </dd> |
| <dt><a id="index-hash"></a><span><code class="code">hash</code><a class="copiable-link" href="#index-hash"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">hash [-r] [-p <var class="var">filename</var>] [-dt] [<var class="var">name</var>] |
| </pre></div> |
| |
| <p>Each time <code class="code">hash</code> is invoked, it remembers the full pathnames of the |
| commands specified as <var class="var">name</var> arguments, |
| so they need not be searched for on subsequent invocations. |
| The commands are found by searching through the directories listed in |
| <code class="env">$PATH</code>. |
| Any previously-remembered pathname is discarded. |
| The <samp class="option">-p</samp> option inhibits the path search, and <var class="var">filename</var> is |
| used as the location of <var class="var">name</var>. |
| The <samp class="option">-r</samp> option causes the shell to forget all remembered locations. |
| The <samp class="option">-d</samp> option causes the shell to forget the remembered location |
| of each <var class="var">name</var>. |
| If the <samp class="option">-t</samp> option is supplied, the full pathname to which each |
| <var class="var">name</var> corresponds is printed. If multiple <var class="var">name</var> arguments are |
| supplied with <samp class="option">-t</samp>, the <var class="var">name</var> is printed before the hashed |
| full pathname. |
| The <samp class="option">-l</samp> option causes output to be displayed in a format |
| that may be reused as input. |
| If no arguments are given, or if only <samp class="option">-l</samp> is supplied, |
| information about remembered commands is printed. |
| The return status is zero unless a <var class="var">name</var> is not found or an invalid |
| option is supplied. |
| </p> |
| </dd> |
| <dt><a id="index-pwd"></a><span><code class="code">pwd</code><a class="copiable-link" href="#index-pwd"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">pwd [-LP] |
| </pre></div> |
| |
| <p>Print the absolute pathname of the current working directory. |
| If the <samp class="option">-P</samp> option is supplied, the pathname printed will not |
| contain symbolic links. |
| If the <samp class="option">-L</samp> option is supplied, the pathname printed may contain |
| symbolic links. |
| The return status is zero unless an error is encountered while |
| determining the name of the current directory or an invalid option |
| is supplied. |
| </p> |
| </dd> |
| <dt><a id="index-readonly"></a><span><code class="code">readonly</code><a class="copiable-link" href="#index-readonly"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">readonly [-aAf] [-p] [<var class="var">name</var>[=<var class="var">value</var>]] ... |
| </pre></div> |
| |
| <p>Mark each <var class="var">name</var> as readonly. |
| The values of these names may not be changed by subsequent assignment. |
| If the <samp class="option">-f</samp> option is supplied, each <var class="var">name</var> refers to a shell |
| function. |
| The <samp class="option">-a</samp> option means each <var class="var">name</var> refers to an indexed |
| array variable; the <samp class="option">-A</samp> option means each <var class="var">name</var> refers |
| to an associative array variable. |
| If both options are supplied, <samp class="option">-A</samp> takes precedence. |
| If no <var class="var">name</var> arguments are given, or if the <samp class="option">-p</samp> |
| option is supplied, a list of all readonly names is printed. |
| The other options may be used to restrict the output to a subset of |
| the set of readonly names. |
| The <samp class="option">-p</samp> option causes output to be displayed in a format that |
| may be reused as input. |
| If a variable name is followed by =<var class="var">value</var>, the value of |
| the variable is set to <var class="var">value</var>. |
| The return status is zero unless an invalid option is supplied, one of |
| the <var class="var">name</var> arguments is not a valid shell variable or function name, |
| or the <samp class="option">-f</samp> option is supplied with a name that is not a shell function. |
| </p> |
| </dd> |
| <dt><a id="index-return"></a><span><code class="code">return</code><a class="copiable-link" href="#index-return"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">return [<var class="var">n</var>] |
| </pre></div> |
| |
| <p>Cause a shell function to stop executing and return the value <var class="var">n</var> |
| to its caller. |
| If <var class="var">n</var> is not supplied, the return value is the exit status of the |
| last command executed in the function. |
| If <code class="code">return</code> is executed by a trap handler, the last command used to |
| determine the status is the last command executed before the trap handler. |
| If <code class="code">return</code> is executed during a <code class="code">DEBUG</code> trap, the last command |
| used to determine the status is the last command executed by the trap |
| handler before <code class="code">return</code> was invoked. |
| <code class="code">return</code> may also be used to terminate execution of a script |
| being executed with the <code class="code">.</code> (<code class="code">source</code>) builtin, |
| returning either <var class="var">n</var> or |
| the exit status of the last command executed within the script as the exit |
| status of the script. |
| If <var class="var">n</var> is supplied, the return value is its least significant |
| 8 bits. |
| Any command associated with the <code class="code">RETURN</code> trap is executed |
| before execution resumes after the function or script. |
| The return status is non-zero if <code class="code">return</code> is supplied a non-numeric |
| argument or is used outside a function |
| and not during the execution of a script by <code class="code">.</code> or <code class="code">source</code>. |
| </p> |
| </dd> |
| <dt><a id="index-shift"></a><span><code class="code">shift</code><a class="copiable-link" href="#index-shift"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">shift [<var class="var">n</var>] |
| </pre></div> |
| |
| <p>Shift the positional parameters to the left by <var class="var">n</var>. |
| The positional parameters from <var class="var">n</var>+1 … <code class="code">$#</code> are |
| renamed to <code class="code">$1</code> … <code class="code">$#</code>-<var class="var">n</var>. |
| Parameters represented by the numbers <code class="code">$#</code> down to <code class="code">$#</code>-<var class="var">n</var>+1 |
| are unset. |
| <var class="var">n</var> must be a non-negative number less than or equal to <code class="code">$#</code>. |
| If <var class="var">n</var> is zero or greater than <code class="code">$#</code>, the positional parameters |
| are not changed. |
| If <var class="var">n</var> is not supplied, it is assumed to be 1. |
| The return status is zero unless <var class="var">n</var> is greater than <code class="code">$#</code> or |
| less than zero, non-zero otherwise. |
| </p> |
| </dd> |
| <dt><a class="index-entry-id" id="index-_005b"></a> |
| <a id="index-test"></a><span><code class="code">test</code><a class="copiable-link" href="#index-test"> ¶</a></span></dt> |
| <dt><code class="code">[</code></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">test <var class="var">expr</var> |
| </pre></div> |
| |
| <p>Evaluate a conditional expression <var class="var">expr</var> and return a status of 0 |
| (true) or 1 (false). |
| Each operator and operand must be a separate argument. |
| Expressions are composed of the primaries described below in |
| <a class="ref" href="#Bash-Conditional-Expressions">Bash Conditional Expressions</a>. |
| <code class="code">test</code> does not accept any options, nor does it accept and ignore |
| an argument of <samp class="option">--</samp> as signifying the end of options. |
| </p> |
| <p>When the <code class="code">[</code> form is used, the last argument to the command must |
| be a <code class="code">]</code>. |
| </p> |
| <p>Expressions may be combined using the following operators, listed in |
| decreasing order of precedence. |
| The evaluation depends on the number of arguments; see below. |
| Operator precedence is used when there are five or more arguments. |
| </p> |
| <dl class="table"> |
| <dt><code class="code">! <var class="var">expr</var></code></dt> |
| <dd><p>True if <var class="var">expr</var> is false. |
| </p> |
| </dd> |
| <dt><code class="code">( <var class="var">expr</var> )</code></dt> |
| <dd><p>Returns the value of <var class="var">expr</var>. |
| This may be used to override the normal precedence of operators. |
| </p> |
| </dd> |
| <dt><code class="code"><var class="var">expr1</var> -a <var class="var">expr2</var></code></dt> |
| <dd><p>True if both <var class="var">expr1</var> and <var class="var">expr2</var> are true. |
| </p> |
| </dd> |
| <dt><code class="code"><var class="var">expr1</var> -o <var class="var">expr2</var></code></dt> |
| <dd><p>True if either <var class="var">expr1</var> or <var class="var">expr2</var> is true. |
| </p></dd> |
| </dl> |
| |
| <p>The <code class="code">test</code> and <code class="code">[</code> builtins evaluate conditional |
| expressions using a set of rules based on the number of arguments. |
| </p> |
| <dl class="table"> |
| <dt>0 arguments</dt> |
| <dd><p>The expression is false. |
| </p> |
| </dd> |
| <dt>1 argument</dt> |
| <dd><p>The expression is true if, and only if, the argument is not null. |
| </p> |
| </dd> |
| <dt>2 arguments</dt> |
| <dd><p>If the first argument is ‘<samp class="samp">!</samp>’, the expression is true if and |
| only if the second argument is null. |
| If the first argument is one of the unary conditional operators |
| (see <a class="pxref" href="#Bash-Conditional-Expressions">Bash Conditional Expressions</a>), the expression |
| is true if the unary test is true. |
| If the first argument is not a valid unary operator, the expression is |
| false. |
| </p> |
| </dd> |
| <dt>3 arguments</dt> |
| <dd><p>The following conditions are applied in the order listed. |
| </p> |
| <ol class="enumerate"> |
| <li> If the second argument is one of the binary conditional |
| operators (see <a class="pxref" href="#Bash-Conditional-Expressions">Bash Conditional Expressions</a>), the |
| result of the expression is the result of the binary test using the |
| first and third arguments as operands. |
| The ‘<samp class="samp">-a</samp>’ and ‘<samp class="samp">-o</samp>’ operators are considered binary operators |
| when there are three arguments. |
| </li><li> If the first argument is ‘<samp class="samp">!</samp>’, the value is the negation of |
| the two-argument test using the second and third arguments. |
| </li><li> If the first argument is exactly ‘<samp class="samp">(</samp>’ and the third argument is |
| exactly ‘<samp class="samp">)</samp>’, the result is the one-argument test of the second |
| argument. |
| </li><li> Otherwise, the expression is false. |
| </li></ol> |
| |
| </dd> |
| <dt>4 arguments</dt> |
| <dd><p>The following conditions are applied in the order listed. |
| </p> |
| <ol class="enumerate"> |
| <li> If the first argument is ‘<samp class="samp">!</samp>’, the result is the negation of |
| the three-argument expression composed of the remaining arguments. |
| </li><li> If the first argument is exactly ‘<samp class="samp">(</samp>’ and the fourth argument is |
| exactly ‘<samp class="samp">)</samp>’, the result is the two-argument test of the second |
| and third arguments. |
| </li><li> Otherwise, the expression is parsed and evaluated according to |
| precedence using the rules listed above. |
| </li></ol> |
| |
| </dd> |
| <dt>5 or more arguments</dt> |
| <dd><p>The expression is parsed and evaluated according to precedence |
| using the rules listed above. |
| </p></dd> |
| </dl> |
| |
| <p>When used with <code class="code">test</code> or ‘<samp class="samp">[</samp>’, the ‘<samp class="samp"><</samp>’ and ‘<samp class="samp">></samp>’ |
| operators sort lexicographically using ASCII ordering. |
| </p> |
| </dd> |
| <dt><a id="index-times"></a><span><code class="code">times</code><a class="copiable-link" href="#index-times"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">times |
| </pre></div> |
| |
| <p>Print out the user and system times used by the shell and its children. |
| The return status is zero. |
| </p> |
| </dd> |
| <dt><a id="index-trap"></a><span><code class="code">trap</code><a class="copiable-link" href="#index-trap"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">trap [-lp] [<var class="var">arg</var>] [<var class="var">sigspec</var> ...] |
| </pre></div> |
| |
| <p>The commands in <var class="var">arg</var> are to be read and executed when the |
| shell receives signal <var class="var">sigspec</var>. If <var class="var">arg</var> is absent (and |
| there is a single <var class="var">sigspec</var>) or |
| equal to ‘<samp class="samp">-</samp>’, each specified signal’s disposition is reset |
| to the value it had when the shell was started. |
| If <var class="var">arg</var> is the null string, then the signal specified by |
| each <var class="var">sigspec</var> is ignored by the shell and commands it invokes. |
| If <var class="var">arg</var> is not present and <samp class="option">-p</samp> has been supplied, |
| the shell displays the trap commands associated with each <var class="var">sigspec</var>. |
| If no arguments are supplied, or |
| only <samp class="option">-p</samp> is given, <code class="code">trap</code> prints the list of commands |
| associated with each signal number in a form that may be reused as |
| shell input. |
| The <samp class="option">-l</samp> option causes the shell to print a list of signal names |
| and their corresponding numbers. |
| Each <var class="var">sigspec</var> is either a signal name or a signal number. |
| Signal names are case insensitive and the <code class="code">SIG</code> prefix is optional. |
| </p> |
| <p>If a <var class="var">sigspec</var> |
| is <code class="code">0</code> or <code class="code">EXIT</code>, <var class="var">arg</var> is executed when the shell exits. |
| If a <var class="var">sigspec</var> is <code class="code">DEBUG</code>, the command <var class="var">arg</var> is executed |
| before every simple command, <code class="code">for</code> command, <code class="code">case</code> command, |
| <code class="code">select</code> command, every arithmetic <code class="code">for</code> command, and before |
| the first command executes in a shell function. |
| Refer to the description of the <code class="code">extdebug</code> option to the |
| <code class="code">shopt</code> builtin (see <a class="pxref" href="#The-Shopt-Builtin">The Shopt Builtin</a>) for details of its |
| effect on the <code class="code">DEBUG</code> trap. |
| If a <var class="var">sigspec</var> is <code class="code">RETURN</code>, the command <var class="var">arg</var> is executed |
| each time a shell function or a script executed with the <code class="code">.</code> or |
| <code class="code">source</code> builtins finishes executing. |
| </p> |
| <p>If a <var class="var">sigspec</var> is <code class="code">ERR</code>, the command <var class="var">arg</var> |
| is executed whenever |
| a pipeline (which may consist of a single simple |
| command), a list, or a compound command returns a |
| non-zero exit status, |
| subject to the following conditions. |
| The <code class="code">ERR</code> trap is not executed if the failed command is part of the |
| command list immediately following an <code class="code">until</code> or <code class="code">while</code> keyword, |
| part of the test following the <code class="code">if</code> or <code class="code">elif</code> reserved words, |
| part of a command executed in a <code class="code">&&</code> or <code class="code">||</code> list |
| except the command following the final <code class="code">&&</code> or <code class="code">||</code>, |
| any command in a pipeline but the last, |
| or if the command’s return |
| status is being inverted using <code class="code">!</code>. |
| These are the same conditions obeyed by the <code class="code">errexit</code> (<samp class="option">-e</samp>) |
| option. |
| </p> |
| <p>Signals ignored upon entry to the shell cannot be trapped or reset. |
| Trapped signals that are not being ignored are reset to their original |
| values in a subshell or subshell environment when one is created. |
| </p> |
| <p>The return status is zero unless a <var class="var">sigspec</var> does not specify a |
| valid signal. |
| </p> |
| </dd> |
| <dt><a id="index-umask"></a><span><code class="code">umask</code><a class="copiable-link" href="#index-umask"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">umask [-p] [-S] [<var class="var">mode</var>] |
| </pre></div> |
| |
| <p>Set the shell process’s file creation mask to <var class="var">mode</var>. If |
| <var class="var">mode</var> begins with a digit, it is interpreted as an octal number; |
| if not, it is interpreted as a symbolic mode mask similar |
| to that accepted by the <code class="code">chmod</code> command. If <var class="var">mode</var> is |
| omitted, the current value of the mask is printed. If the <samp class="option">-S</samp> |
| option is supplied without a <var class="var">mode</var> argument, the mask is printed |
| in a symbolic format. |
| If the <samp class="option">-p</samp> option is supplied, and <var class="var">mode</var> |
| is omitted, the output is in a form that may be reused as input. |
| The return status is zero if the mode is successfully changed or if |
| no <var class="var">mode</var> argument is supplied, and non-zero otherwise. |
| </p> |
| <p>Note that when the mode is interpreted as an octal number, each number |
| of the umask is subtracted from <code class="code">7</code>. Thus, a umask of <code class="code">022</code> |
| results in permissions of <code class="code">755</code>. |
| </p> |
| </dd> |
| <dt><a id="index-unset"></a><span><code class="code">unset</code><a class="copiable-link" href="#index-unset"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">unset [-fnv] [<var class="var">name</var>] |
| </pre></div> |
| |
| <p>Remove each variable or function <var class="var">name</var>. |
| If the <samp class="option">-v</samp> option is given, each |
| <var class="var">name</var> refers to a shell variable and that variable is removed. |
| If the <samp class="option">-f</samp> option is given, the <var class="var">name</var>s refer to shell |
| functions, and the function definition is removed. |
| If the <samp class="option">-n</samp> option is supplied, and <var class="var">name</var> is a variable with |
| the <code class="code">nameref</code> attribute, <var class="var">name</var> will be unset rather than the |
| variable it references. |
| <samp class="option">-n</samp> has no effect if the <samp class="option">-f</samp> option is supplied. |
| If no options are supplied, each <var class="var">name</var> refers to a variable; if |
| there is no variable by that name, a function with that name, if any, is |
| unset. |
| Readonly variables and functions may not be unset. |
| Some shell variables lose their special behavior if they are unset; such |
| behavior is noted in the description of the individual variables. |
| The return status is zero unless a <var class="var">name</var> is readonly or may not be unset. |
| </p></dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Bash-Builtins"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Modifying-Shell-Behavior" accesskey="n" rel="next">Modifying Shell Behavior</a>, Previous: <a href="#Bourne-Shell-Builtins" accesskey="p" rel="prev">Bourne Shell Builtins</a>, Up: <a href="#Shell-Builtin-Commands" accesskey="u" rel="up">Shell Builtin Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Bash-Builtin-Commands"><span>4.2 Bash Builtin Commands<a class="copiable-link" href="#Bash-Builtin-Commands"> ¶</a></span></h3> |
| |
| <p>This section describes builtin commands which are unique to |
| or have been extended in Bash. |
| Some of these commands are specified in the <small class="sc">POSIX</small> standard. |
| </p> |
| <dl class="table"> |
| <dt><a id="index-alias"></a><span><code class="code">alias</code><a class="copiable-link" href="#index-alias"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">alias [-p] [<var class="var">name</var>[=<var class="var">value</var>] ...] |
| </pre></div> |
| |
| <p>Without arguments or with the <samp class="option">-p</samp> option, <code class="code">alias</code> prints |
| the list of aliases on the standard output in a form that allows |
| them to be reused as input. |
| If arguments are supplied, an alias is defined for each <var class="var">name</var> |
| whose <var class="var">value</var> is given. If no <var class="var">value</var> is given, the name |
| and value of the alias is printed. |
| Aliases are described in <a class="ref" href="#Aliases">Aliases</a>. |
| </p> |
| </dd> |
| <dt><a id="index-bind"></a><span><code class="code">bind</code><a class="copiable-link" href="#index-bind"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">bind [-m <var class="var">keymap</var>] [-lpsvPSVX] |
| bind [-m <var class="var">keymap</var>] [-q <var class="var">function</var>] [-u <var class="var">function</var>] [-r <var class="var">keyseq</var>] |
| bind [-m <var class="var">keymap</var>] -f <var class="var">filename</var> |
| bind [-m <var class="var">keymap</var>] -x <var class="var">keyseq:shell-command</var> |
| bind [-m <var class="var">keymap</var>] <var class="var">keyseq:function-name</var> |
| bind [-m <var class="var">keymap</var>] <var class="var">keyseq:readline-command</var> |
| bind <var class="var">readline-command-line</var> |
| </pre></div> |
| |
| <p>Display current Readline (see <a class="pxref" href="#Command-Line-Editing">Command Line Editing</a>) |
| key and function bindings, |
| bind a key sequence to a Readline function or macro, |
| or set a Readline variable. |
| Each non-option argument is a command as it would appear in a |
| Readline initialization file (see <a class="pxref" href="#Readline-Init-File">Readline Init File</a>), |
| but each binding or command must be passed as a separate argument; e.g., |
| ‘<samp class="samp">"\C-x\C-r":re-read-init-file</samp>’. |
| </p> |
| <p>Options, if supplied, have the following meanings: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">-m <var class="var">keymap</var></code></dt> |
| <dd><p>Use <var class="var">keymap</var> as the keymap to be affected by |
| the subsequent bindings. Acceptable <var class="var">keymap</var> |
| names are |
| <code class="code">emacs</code>, |
| <code class="code">emacs-standard</code>, |
| <code class="code">emacs-meta</code>, |
| <code class="code">emacs-ctlx</code>, |
| <code class="code">vi</code>, |
| <code class="code">vi-move</code>, |
| <code class="code">vi-command</code>, and |
| <code class="code">vi-insert</code>. |
| <code class="code">vi</code> is equivalent to <code class="code">vi-command</code> (<code class="code">vi-move</code> is also a |
| synonym); <code class="code">emacs</code> is equivalent to <code class="code">emacs-standard</code>. |
| </p> |
| </dd> |
| <dt><code class="code">-l</code></dt> |
| <dd><p>List the names of all Readline functions. |
| </p> |
| </dd> |
| <dt><code class="code">-p</code></dt> |
| <dd><p>Display Readline function names and bindings in such a way that they |
| can be used as input or in a Readline initialization file. |
| </p> |
| </dd> |
| <dt><code class="code">-P</code></dt> |
| <dd><p>List current Readline function names and bindings. |
| </p> |
| </dd> |
| <dt><code class="code">-v</code></dt> |
| <dd><p>Display Readline variable names and values in such a way that they |
| can be used as input or in a Readline initialization file. |
| </p> |
| </dd> |
| <dt><code class="code">-V</code></dt> |
| <dd><p>List current Readline variable names and values. |
| </p> |
| </dd> |
| <dt><code class="code">-s</code></dt> |
| <dd><p>Display Readline key sequences bound to macros and the strings they output |
| in such a way that they can be used as input or in a Readline |
| initialization file. |
| </p> |
| </dd> |
| <dt><code class="code">-S</code></dt> |
| <dd><p>Display Readline key sequences bound to macros and the strings they output. |
| </p> |
| </dd> |
| <dt><code class="code">-f <var class="var">filename</var></code></dt> |
| <dd><p>Read key bindings from <var class="var">filename</var>. |
| </p> |
| </dd> |
| <dt><code class="code">-q <var class="var">function</var></code></dt> |
| <dd><p>Query about which keys invoke the named <var class="var">function</var>. |
| </p> |
| </dd> |
| <dt><code class="code">-u <var class="var">function</var></code></dt> |
| <dd><p>Unbind all keys bound to the named <var class="var">function</var>. |
| </p> |
| </dd> |
| <dt><code class="code">-r <var class="var">keyseq</var></code></dt> |
| <dd><p>Remove any current binding for <var class="var">keyseq</var>. |
| </p> |
| </dd> |
| <dt><code class="code">-x <var class="var">keyseq:shell-command</var></code></dt> |
| <dd><p>Cause <var class="var">shell-command</var> to be executed whenever <var class="var">keyseq</var> is |
| entered. |
| When <var class="var">shell-command</var> is executed, the shell sets the |
| <code class="code">READLINE_LINE</code> variable to the contents of the Readline line |
| buffer and the <code class="code">READLINE_POINT</code> and <code class="code">READLINE_MARK</code> variables |
| to the current location of the insertion point and the saved insertion |
| point (the <var class="var">mark</var>), respectively. |
| The shell assigns any numeric argument the user supplied to the |
| <code class="code">READLINE_ARGUMENT</code> variable. |
| If there was no argument, that variable is not set. |
| If the executed command changes the value of any of <code class="code">READLINE_LINE</code>, |
| <code class="code">READLINE_POINT</code>, or <code class="code">READLINE_MARK</code>, those new values will be |
| reflected in the editing state. |
| </p> |
| </dd> |
| <dt><code class="code">-X</code></dt> |
| <dd><p>List all key sequences bound to shell commands and the associated commands |
| in a format that can be reused as input. |
| </p></dd> |
| </dl> |
| |
| <p>The return status is zero unless an invalid option is supplied or an |
| error occurs. |
| </p> |
| </dd> |
| <dt><a id="index-builtin"></a><span><code class="code">builtin</code><a class="copiable-link" href="#index-builtin"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">builtin [<var class="var">shell-builtin</var> [<var class="var">args</var>]] |
| </pre></div> |
| |
| <p>Run a shell builtin, passing it <var class="var">args</var>, and return its exit status. |
| This is useful when defining a shell function with the same |
| name as a shell builtin, retaining the functionality of the builtin within |
| the function. |
| The return status is non-zero if <var class="var">shell-builtin</var> is not a shell |
| builtin command. |
| </p> |
| </dd> |
| <dt><a id="index-caller"></a><span><code class="code">caller</code><a class="copiable-link" href="#index-caller"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">caller [<var class="var">expr</var>] |
| </pre></div> |
| |
| <p>Returns the context of any active subroutine call (a shell function or |
| a script executed with the <code class="code">.</code> or <code class="code">source</code> builtins). |
| </p> |
| <p>Without <var class="var">expr</var>, <code class="code">caller</code> displays the line number and source |
| filename of the current subroutine call. |
| If a non-negative integer is supplied as <var class="var">expr</var>, <code class="code">caller</code> |
| displays the line number, subroutine name, and source file corresponding |
| to that position in the current execution call stack. This extra |
| information may be used, for example, to print a stack trace. The |
| current frame is frame 0. |
| </p> |
| <p>The return value is 0 unless the shell is not executing a subroutine |
| call or <var class="var">expr</var> does not correspond to a valid position in the |
| call stack. |
| </p> |
| </dd> |
| <dt><a id="index-command"></a><span><code class="code">command</code><a class="copiable-link" href="#index-command"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">command [-pVv] <var class="var">command</var> [<var class="var">arguments</var> ...] |
| </pre></div> |
| |
| <p>Runs <var class="var">command</var> with <var class="var">arguments</var> ignoring any shell function |
| named <var class="var">command</var>. |
| Only shell builtin commands or commands found by searching the |
| <code class="env">PATH</code> are executed. |
| If there is a shell function named <code class="code">ls</code>, running ‘<samp class="samp">command ls</samp>’ |
| within the function will execute the external command <code class="code">ls</code> |
| instead of calling the function recursively. |
| The <samp class="option">-p</samp> option means to use a default value for <code class="env">PATH</code> |
| that is guaranteed to find all of the standard utilities. |
| The return status in this case is 127 if <var class="var">command</var> cannot be |
| found or an error occurred, and the exit status of <var class="var">command</var> |
| otherwise. |
| </p> |
| <p>If either the <samp class="option">-V</samp> or <samp class="option">-v</samp> option is supplied, a |
| description of <var class="var">command</var> is printed. The <samp class="option">-v</samp> option |
| causes a single word indicating the command or file name used to |
| invoke <var class="var">command</var> to be displayed; the <samp class="option">-V</samp> option produces |
| a more verbose description. In this case, the return status is |
| zero if <var class="var">command</var> is found, and non-zero if not. |
| </p> |
| </dd> |
| <dt><a id="index-declare"></a><span><code class="code">declare</code><a class="copiable-link" href="#index-declare"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">declare [-aAfFgiIlnrtux] [-p] [<var class="var">name</var>[=<var class="var">value</var>] ...] |
| </pre></div> |
| |
| <p>Declare variables and give them attributes. If no <var class="var">name</var>s |
| are given, then display the values of variables instead. |
| </p> |
| <p>The <samp class="option">-p</samp> option will display the attributes and values of each |
| <var class="var">name</var>. |
| When <samp class="option">-p</samp> is used with <var class="var">name</var> arguments, additional options, |
| other than <samp class="option">-f</samp> and <samp class="option">-F</samp>, are ignored. |
| </p> |
| <p>When <samp class="option">-p</samp> is supplied without <var class="var">name</var> arguments, <code class="code">declare</code> |
| will display the attributes and values of all variables having the |
| attributes specified by the additional options. |
| If no other options are supplied with <samp class="option">-p</samp>, <code class="code">declare</code> will |
| display the attributes and values of all shell variables. The <samp class="option">-f</samp> |
| option will restrict the display to shell functions. |
| </p> |
| <p>The <samp class="option">-F</samp> option inhibits the display of function definitions; |
| only the function name and attributes are printed. |
| If the <code class="code">extdebug</code> shell option is enabled using <code class="code">shopt</code> |
| (see <a class="pxref" href="#The-Shopt-Builtin">The Shopt Builtin</a>), the source file name and line number where |
| each <var class="var">name</var> is defined are displayed as well. |
| <samp class="option">-F</samp> implies <samp class="option">-f</samp>. |
| </p> |
| <p>The <samp class="option">-g</samp> option forces variables to be created or modified at |
| the global scope, even when <code class="code">declare</code> is executed in a shell function. |
| It is ignored in all other cases. |
| </p> |
| <p>The <samp class="option">-I</samp> option causes local variables to inherit the attributes |
| (except the <code class="code">nameref</code> attribute) |
| and value of any existing variable with the same |
| <var class="var">name</var> at a surrounding scope. |
| If there is no existing variable, the local variable is initially unset. |
| </p> |
| <p>The following options can be used to restrict output to variables with |
| the specified attributes or to give variables attributes: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">-a</code></dt> |
| <dd><p>Each <var class="var">name</var> is an indexed array variable (see <a class="pxref" href="#Arrays">Arrays</a>). |
| </p> |
| </dd> |
| <dt><code class="code">-A</code></dt> |
| <dd><p>Each <var class="var">name</var> is an associative array variable (see <a class="pxref" href="#Arrays">Arrays</a>). |
| </p> |
| </dd> |
| <dt><code class="code">-f</code></dt> |
| <dd><p>Use function names only. |
| </p> |
| </dd> |
| <dt><code class="code">-i</code></dt> |
| <dd><p>The variable is to be treated as |
| an integer; arithmetic evaluation (see <a class="pxref" href="#Shell-Arithmetic">Shell Arithmetic</a>) is |
| performed when the variable is assigned a value. |
| </p> |
| </dd> |
| <dt><code class="code">-l</code></dt> |
| <dd><p>When the variable is assigned a value, all upper-case characters are |
| converted to lower-case. |
| The upper-case attribute is disabled. |
| </p> |
| </dd> |
| <dt><code class="code">-n</code></dt> |
| <dd><p>Give each <var class="var">name</var> the <code class="code">nameref</code> attribute, making |
| it a name reference to another variable. |
| That other variable is defined by the value of <var class="var">name</var>. |
| All references, assignments, and attribute modifications |
| to <var class="var">name</var>, except for those using or changing the |
| <samp class="option">-n</samp> attribute itself, are performed on the variable referenced by |
| <var class="var">name</var>’s value. |
| The nameref attribute cannot be applied to array variables. |
| </p> |
| </dd> |
| <dt><code class="code">-r</code></dt> |
| <dd><p>Make <var class="var">name</var>s readonly. These names cannot then be assigned values |
| by subsequent assignment statements or unset. |
| </p> |
| </dd> |
| <dt><code class="code">-t</code></dt> |
| <dd><p>Give each <var class="var">name</var> the <code class="code">trace</code> attribute. |
| Traced functions inherit the <code class="code">DEBUG</code> and <code class="code">RETURN</code> traps from |
| the calling shell. |
| The trace attribute has no special meaning for variables. |
| </p> |
| </dd> |
| <dt><code class="code">-u</code></dt> |
| <dd><p>When the variable is assigned a value, all lower-case characters are |
| converted to upper-case. |
| The lower-case attribute is disabled. |
| </p> |
| </dd> |
| <dt><code class="code">-x</code></dt> |
| <dd><p>Mark each <var class="var">name</var> for export to subsequent commands via |
| the environment. |
| </p></dd> |
| </dl> |
| |
| <p>Using ‘<samp class="samp">+</samp>’ instead of ‘<samp class="samp">-</samp>’ turns off the attribute instead, |
| with the exceptions that ‘<samp class="samp">+a</samp>’ and ‘<samp class="samp">+A</samp>’ |
| may not be used to destroy array variables and ‘<samp class="samp">+r</samp>’ will not |
| remove the readonly attribute. |
| When used in a function, <code class="code">declare</code> makes each <var class="var">name</var> local, |
| as with the <code class="code">local</code> command, unless the <samp class="option">-g</samp> option is used. |
| If a variable name is followed by =<var class="var">value</var>, the value of the variable |
| is set to <var class="var">value</var>. |
| </p> |
| <p>When using <samp class="option">-a</samp> or <samp class="option">-A</samp> and the compound assignment syntax to |
| create array variables, additional attributes do not take effect until |
| subsequent assignments. |
| </p> |
| <p>The return status is zero unless an invalid option is encountered, |
| an attempt is made to define a function using ‘<samp class="samp">-f foo=bar</samp>’, |
| an attempt is made to assign a value to a readonly variable, |
| an attempt is made to assign a value to an array variable without |
| using the compound assignment syntax (see <a class="pxref" href="#Arrays">Arrays</a>), |
| one of the <var class="var">name</var>s is not a valid shell variable name, |
| an attempt is made to turn off readonly status for a readonly variable, |
| an attempt is made to turn off array status for an array variable, |
| or an attempt is made to display a non-existent function with <samp class="option">-f</samp>. |
| </p> |
| </dd> |
| <dt><a id="index-echo"></a><span><code class="code">echo</code><a class="copiable-link" href="#index-echo"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">echo [-neE] [<var class="var">arg</var> ...] |
| </pre></div> |
| |
| <p>Output the <var class="var">arg</var>s, separated by spaces, terminated with a |
| newline. |
| The return status is 0 unless a write error occurs. |
| If <samp class="option">-n</samp> is specified, the trailing newline is suppressed. |
| If the <samp class="option">-e</samp> option is given, interpretation of the following |
| backslash-escaped characters is enabled. |
| The <samp class="option">-E</samp> option disables the interpretation of these escape characters, |
| even on systems where they are interpreted by default. |
| The <code class="code">xpg_echo</code> shell option may be used to |
| dynamically determine whether or not <code class="code">echo</code> expands these |
| escape characters by default. |
| <code class="code">echo</code> does not interpret <samp class="option">--</samp> to mean the end of options. |
| </p> |
| <p><code class="code">echo</code> interprets the following escape sequences: |
| </p><dl class="table"> |
| <dt><code class="code">\a</code></dt> |
| <dd><p>alert (bell) |
| </p></dd> |
| <dt><code class="code">\b</code></dt> |
| <dd><p>backspace |
| </p></dd> |
| <dt><code class="code">\c</code></dt> |
| <dd><p>suppress further output |
| </p></dd> |
| <dt><code class="code">\e</code></dt> |
| <dt><code class="code">\E</code></dt> |
| <dd><p>escape |
| </p></dd> |
| <dt><code class="code">\f</code></dt> |
| <dd><p>form feed |
| </p></dd> |
| <dt><code class="code">\n</code></dt> |
| <dd><p>new line |
| </p></dd> |
| <dt><code class="code">\r</code></dt> |
| <dd><p>carriage return |
| </p></dd> |
| <dt><code class="code">\t</code></dt> |
| <dd><p>horizontal tab |
| </p></dd> |
| <dt><code class="code">\v</code></dt> |
| <dd><p>vertical tab |
| </p></dd> |
| <dt><code class="code">\\</code></dt> |
| <dd><p>backslash |
| </p></dd> |
| <dt><code class="code">\0<var class="var">nnn</var></code></dt> |
| <dd><p>the eight-bit character whose value is the octal value <var class="var">nnn</var> |
| (zero to three octal digits) |
| </p></dd> |
| <dt><code class="code">\x<var class="var">HH</var></code></dt> |
| <dd><p>the eight-bit character whose value is the hexadecimal value <var class="var">HH</var> |
| (one or two hex digits) |
| </p></dd> |
| <dt><code class="code">\u<var class="var">HHHH</var></code></dt> |
| <dd><p>the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value |
| <var class="var">HHHH</var> (one to four hex digits) |
| </p></dd> |
| <dt><code class="code">\U<var class="var">HHHHHHHH</var></code></dt> |
| <dd><p>the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value |
| <var class="var">HHHHHHHH</var> (one to eight hex digits) |
| </p></dd> |
| </dl> |
| |
| </dd> |
| <dt><a id="index-enable"></a><span><code class="code">enable</code><a class="copiable-link" href="#index-enable"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">enable [-a] [-dnps] [-f <var class="var">filename</var>] [<var class="var">name</var> ...] |
| </pre></div> |
| |
| <p>Enable and disable builtin shell commands. |
| Disabling a builtin allows a disk command which has the same name |
| as a shell builtin to be executed without specifying a full pathname, |
| even though the shell normally searches for builtins before disk commands. |
| If <samp class="option">-n</samp> is used, the <var class="var">name</var>s become disabled. Otherwise |
| <var class="var">name</var>s are enabled. For example, to use the <code class="code">test</code> binary |
| found via <code class="env">$PATH</code> instead of the shell builtin version, type |
| ‘<samp class="samp">enable -n test</samp>’. |
| </p> |
| <p>If the <samp class="option">-p</samp> option is supplied, or no <var class="var">name</var> arguments appear, |
| a list of shell builtins is printed. With no other arguments, the list |
| consists of all enabled shell builtins. |
| The <samp class="option">-a</samp> option means to list |
| each builtin with an indication of whether or not it is enabled. |
| </p> |
| <p>The <samp class="option">-f</samp> option means to load the new builtin command <var class="var">name</var> |
| from shared object <var class="var">filename</var>, on systems that support dynamic loading. |
| Bash will use the value of the <code class="env">BASH_LOADABLES_PATH</code> variable as a |
| colon-separated list of directories in which to search for <var class="var">filename</var>. |
| The default is system-dependent. |
| The <samp class="option">-d</samp> option will delete a builtin loaded with <samp class="option">-f</samp>. |
| </p> |
| <p>If there are no options, a list of the shell builtins is displayed. |
| The <samp class="option">-s</samp> option restricts <code class="code">enable</code> to the <small class="sc">POSIX</small> special |
| builtins. If <samp class="option">-s</samp> is used with <samp class="option">-f</samp>, the new builtin becomes |
| a special builtin (see <a class="pxref" href="#Special-Builtins">Special Builtins</a>). |
| </p> |
| <p>If no options are supplied and a <var class="var">name</var> is not a shell builtin, |
| <code class="code">enable</code> will attempt to load <var class="var">name</var> from a shared object named |
| <var class="var">name</var>, as if the command were |
| ‘<samp class="samp">enable -f <var class="var">name</var> <var class="var">name</var></samp>’. |
| </p> |
| <p>The return status is zero unless a <var class="var">name</var> is not a shell builtin |
| or there is an error loading a new builtin from a shared object. |
| </p> |
| </dd> |
| <dt><a id="index-help"></a><span><code class="code">help</code><a class="copiable-link" href="#index-help"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">help [-dms] [<var class="var">pattern</var>] |
| </pre></div> |
| |
| <p>Display helpful information about builtin commands. |
| If <var class="var">pattern</var> is specified, <code class="code">help</code> gives detailed help |
| on all commands matching <var class="var">pattern</var>, otherwise a list of |
| the builtins is printed. |
| </p> |
| <p>Options, if supplied, have the following meanings: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">-d</code></dt> |
| <dd><p>Display a short description of each <var class="var">pattern</var> |
| </p></dd> |
| <dt><code class="code">-m</code></dt> |
| <dd><p>Display the description of each <var class="var">pattern</var> in a manpage-like format |
| </p></dd> |
| <dt><code class="code">-s</code></dt> |
| <dd><p>Display only a short usage synopsis for each <var class="var">pattern</var> |
| </p></dd> |
| </dl> |
| |
| <p>The return status is zero unless no command matches <var class="var">pattern</var>. |
| </p> |
| </dd> |
| <dt><a id="index-let"></a><span><code class="code">let</code><a class="copiable-link" href="#index-let"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">let <var class="var">expression</var> [<var class="var">expression</var> ...] |
| </pre></div> |
| |
| <p>The <code class="code">let</code> builtin allows arithmetic to be performed on shell |
| variables. Each <var class="var">expression</var> is evaluated according to the |
| rules given below in <a class="ref" href="#Shell-Arithmetic">Shell Arithmetic</a>. If the |
| last <var class="var">expression</var> evaluates to 0, <code class="code">let</code> returns 1; |
| otherwise 0 is returned. |
| </p> |
| </dd> |
| <dt><a id="index-local"></a><span><code class="code">local</code><a class="copiable-link" href="#index-local"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">local [<var class="var">option</var>] <var class="var">name</var>[=<var class="var">value</var>] ... |
| </pre></div> |
| |
| <p>For each argument, a local variable named <var class="var">name</var> is created, |
| and assigned <var class="var">value</var>. |
| The <var class="var">option</var> can be any of the options accepted by <code class="code">declare</code>. |
| <code class="code">local</code> can only be used within a function; it makes the variable |
| <var class="var">name</var> have a visible scope restricted to that function and its |
| children. |
| If <var class="var">name</var> is ‘<samp class="samp">-</samp>’, the set of shell options is made local to the |
| function in which <code class="code">local</code> is invoked: shell options changed using |
| the <code class="code">set</code> builtin inside the function are restored to their original |
| values when the function returns. |
| The restore is effected as if a series of <code class="code">set</code> commands were executed |
| to restore the values that were in place before the function. |
| The return status is zero unless <code class="code">local</code> is used outside |
| a function, an invalid <var class="var">name</var> is supplied, or <var class="var">name</var> is a |
| readonly variable. |
| </p> |
| </dd> |
| <dt><a id="index-logout"></a><span><code class="code">logout</code><a class="copiable-link" href="#index-logout"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">logout [<var class="var">n</var>] |
| </pre></div> |
| |
| <p>Exit a login shell, returning a status of <var class="var">n</var> to the shell’s |
| parent. |
| </p> |
| </dd> |
| <dt><a id="index-mapfile"></a><span><code class="code">mapfile</code><a class="copiable-link" href="#index-mapfile"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">mapfile [-d <var class="var">delim</var>] [-n <var class="var">count</var>] [-O <var class="var">origin</var>] [-s <var class="var">count</var>] |
| [-t] [-u <var class="var">fd</var>] [-C <var class="var">callback</var>] [-c <var class="var">quantum</var>] [<var class="var">array</var>] |
| </pre></div> |
| |
| <p>Read lines from the standard input into the indexed array variable <var class="var">array</var>, |
| or from file descriptor <var class="var">fd</var> |
| if the <samp class="option">-u</samp> option is supplied. |
| The variable <code class="code">MAPFILE</code> is the default <var class="var">array</var>. |
| Options, if supplied, have the following meanings: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">-d</code></dt> |
| <dd><p>The first character of <var class="var">delim</var> is used to terminate each input line, |
| rather than newline. |
| If <var class="var">delim</var> is the empty string, <code class="code">mapfile</code> will terminate a line |
| when it reads a NUL character. |
| </p></dd> |
| <dt><code class="code">-n</code></dt> |
| <dd><p>Copy at most <var class="var">count</var> lines. If <var class="var">count</var> is 0, all lines are copied. |
| </p></dd> |
| <dt><code class="code">-O</code></dt> |
| <dd><p>Begin assigning to <var class="var">array</var> at index <var class="var">origin</var>. |
| The default index is 0. |
| </p></dd> |
| <dt><code class="code">-s</code></dt> |
| <dd><p>Discard the first <var class="var">count</var> lines read. |
| </p></dd> |
| <dt><code class="code">-t</code></dt> |
| <dd><p>Remove a trailing <var class="var">delim</var> (default newline) from each line read. |
| </p></dd> |
| <dt><code class="code">-u</code></dt> |
| <dd><p>Read lines from file descriptor <var class="var">fd</var> instead of the standard input. |
| </p></dd> |
| <dt><code class="code">-C</code></dt> |
| <dd><p>Evaluate <var class="var">callback</var> each time <var class="var">quantum</var> lines are read. |
| The <samp class="option">-c</samp> option specifies <var class="var">quantum</var>. |
| </p></dd> |
| <dt><code class="code">-c</code></dt> |
| <dd><p>Specify the number of lines read between each call to <var class="var">callback</var>. |
| </p></dd> |
| </dl> |
| |
| <p>If <samp class="option">-C</samp> is specified without <samp class="option">-c</samp>, |
| the default quantum is 5000. |
| When <var class="var">callback</var> is evaluated, it is supplied the index of the next |
| array element to be assigned and the line to be assigned to that element |
| as additional arguments. |
| <var class="var">callback</var> is evaluated after the line is read but before the |
| array element is assigned. |
| </p> |
| <p>If not supplied with an explicit origin, <code class="code">mapfile</code> will clear <var class="var">array</var> |
| before assigning to it. |
| </p> |
| <p><code class="code">mapfile</code> returns successfully unless an invalid option or option |
| argument is supplied, <var class="var">array</var> is invalid or unassignable, or <var class="var">array</var> |
| is not an indexed array. |
| </p> |
| </dd> |
| <dt><a id="index-printf"></a><span><code class="code">printf</code><a class="copiable-link" href="#index-printf"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">printf [-v <var class="var">var</var>] <var class="var">format</var> [<var class="var">arguments</var>] |
| </pre></div> |
| |
| <p>Write the formatted <var class="var">arguments</var> to the standard output under the |
| control of the <var class="var">format</var>. |
| The <samp class="option">-v</samp> option causes the output to be assigned to the variable |
| <var class="var">var</var> rather than being printed to the standard output. |
| </p> |
| <p>The <var class="var">format</var> is a character string which contains three types of objects: |
| plain characters, which are simply copied to standard output, character |
| escape sequences, which are converted and copied to the standard output, and |
| format specifications, each of which causes printing of the next successive |
| <var class="var">argument</var>. |
| In addition to the standard <code class="code">printf(1)</code> formats, <code class="code">printf</code> |
| interprets the following extensions: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">%b</code></dt> |
| <dd><p>Causes <code class="code">printf</code> to expand backslash escape sequences in the |
| corresponding <var class="var">argument</var> in the same way as <code class="code">echo -e</code> |
| (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>). |
| </p></dd> |
| <dt><code class="code">%q</code></dt> |
| <dd><p>Causes <code class="code">printf</code> to output the |
| corresponding <var class="var">argument</var> in a format that can be reused as shell input. |
| </p></dd> |
| <dt><code class="code">%Q</code></dt> |
| <dd><p>like <code class="code">%q</code>, but applies any supplied precision to the <var class="var">argument</var> |
| before quoting it. |
| </p></dd> |
| <dt><code class="code">%(<var class="var">datefmt</var>)T</code></dt> |
| <dd><p>Causes <code class="code">printf</code> to output the date-time string resulting from using |
| <var class="var">datefmt</var> as a format string for <code class="code">strftime</code>(3). |
| The corresponding <var class="var">argument</var> is an integer representing the number of |
| seconds since the epoch. |
| Two special argument values may be used: -1 represents the current |
| time, and -2 represents the time the shell was invoked. |
| If no argument is specified, conversion behaves as if -1 had been given. |
| This is an exception to the usual <code class="code">printf</code> behavior. |
| </p></dd> |
| </dl> |
| |
| <p>The %b, %q, and %T directives all use the field width and precision |
| arguments from the format specification and write that many bytes from |
| (or use that wide a field for) the expanded argument, which usually |
| contains more characters than the original. |
| </p> |
| <p>Arguments to non-string format specifiers are treated as C language constants, |
| except that a leading plus or minus sign is allowed, and if the leading |
| character is a single or double quote, the value is the ASCII value of |
| the following character. |
| </p> |
| <p>The <var class="var">format</var> is reused as necessary to consume all of the <var class="var">arguments</var>. |
| If the <var class="var">format</var> requires more <var class="var">arguments</var> than are supplied, the |
| extra format specifications behave as if a zero value or null string, as |
| appropriate, had been supplied. The return value is zero on success, |
| non-zero on failure. |
| </p> |
| </dd> |
| <dt><a id="index-read"></a><span><code class="code">read</code><a class="copiable-link" href="#index-read"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">read [-ers] [-a <var class="var">aname</var>] [-d <var class="var">delim</var>] [-i <var class="var">text</var>] [-n <var class="var">nchars</var>] |
| [-N <var class="var">nchars</var>] [-p <var class="var">prompt</var>] [-t <var class="var">timeout</var>] [-u <var class="var">fd</var>] [<var class="var">name</var> ...] |
| </pre></div> |
| |
| <p>One line is read from the standard input, or from the file descriptor |
| <var class="var">fd</var> supplied as an argument to the <samp class="option">-u</samp> option, |
| split into words as described above in <a class="ref" href="#Word-Splitting">Word Splitting</a>, |
| and the first word |
| is assigned to the first <var class="var">name</var>, the second word to the second <var class="var">name</var>, |
| and so on. |
| If there are more words than names, |
| the remaining words and their intervening delimiters are assigned |
| to the last <var class="var">name</var>. |
| If there are fewer words read from the input stream than names, |
| the remaining names are assigned empty values. |
| The characters in the value of the <code class="env">IFS</code> variable |
| are used to split the line into words using the same rules the shell |
| uses for expansion (described above in <a class="ref" href="#Word-Splitting">Word Splitting</a>). |
| The backslash character ‘<samp class="samp">\</samp>’ may be used to remove any special |
| meaning for the next character read and for line continuation. |
| </p> |
| <p>Options, if supplied, have the following meanings: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">-a <var class="var">aname</var></code></dt> |
| <dd><p>The words are assigned to sequential indices of the array variable |
| <var class="var">aname</var>, starting at 0. |
| All elements are removed from <var class="var">aname</var> before the assignment. |
| Other <var class="var">name</var> arguments are ignored. |
| </p> |
| </dd> |
| <dt><code class="code">-d <var class="var">delim</var></code></dt> |
| <dd><p>The first character of <var class="var">delim</var> is used to terminate the input line, |
| rather than newline. |
| If <var class="var">delim</var> is the empty string, <code class="code">read</code> will terminate a line |
| when it reads a NUL character. |
| </p> |
| </dd> |
| <dt><code class="code">-e</code></dt> |
| <dd><p>Readline (see <a class="pxref" href="#Command-Line-Editing">Command Line Editing</a>) is used to obtain the line. |
| Readline uses the current (or default, if line editing was not previously |
| active) editing settings, but uses Readline’s default filename completion. |
| </p> |
| </dd> |
| <dt><code class="code">-i <var class="var">text</var></code></dt> |
| <dd><p>If Readline is being used to read the line, <var class="var">text</var> is placed into |
| the editing buffer before editing begins. |
| </p> |
| </dd> |
| <dt><code class="code">-n <var class="var">nchars</var></code></dt> |
| <dd><p><code class="code">read</code> returns after reading <var class="var">nchars</var> characters rather than |
| waiting for a complete line of input, but honors a delimiter if fewer |
| than <var class="var">nchars</var> characters are read before the delimiter. |
| </p> |
| </dd> |
| <dt><code class="code">-N <var class="var">nchars</var></code></dt> |
| <dd><p><code class="code">read</code> returns after reading exactly <var class="var">nchars</var> characters rather |
| than waiting for a complete line of input, unless EOF is encountered or |
| <code class="code">read</code> times out. |
| Delimiter characters encountered in the input are |
| not treated specially and do not cause <code class="code">read</code> to return until |
| <var class="var">nchars</var> characters are read. |
| The result is not split on the characters in <code class="code">IFS</code>; the intent is |
| that the variable is assigned exactly the characters read |
| (with the exception of backslash; see the <samp class="option">-r</samp> option below). |
| </p> |
| </dd> |
| <dt><code class="code">-p <var class="var">prompt</var></code></dt> |
| <dd><p>Display <var class="var">prompt</var>, without a trailing newline, before attempting |
| to read any input. |
| The prompt is displayed only if input is coming from a terminal. |
| </p> |
| </dd> |
| <dt><code class="code">-r</code></dt> |
| <dd><p>If this option is given, backslash does not act as an escape character. |
| The backslash is considered to be part of the line. |
| In particular, a backslash-newline pair may not then be used as a line |
| continuation. |
| </p> |
| </dd> |
| <dt><code class="code">-s</code></dt> |
| <dd><p>Silent mode. If input is coming from a terminal, characters are |
| not echoed. |
| </p> |
| </dd> |
| <dt><code class="code">-t <var class="var">timeout</var></code></dt> |
| <dd><p>Cause <code class="code">read</code> to time out and return failure if a complete line of |
| input (or a specified number of characters) |
| is not read within <var class="var">timeout</var> seconds. |
| <var class="var">timeout</var> may be a decimal number with a fractional portion following |
| the decimal point. |
| This option is only effective if <code class="code">read</code> is reading input from a |
| terminal, pipe, or other special file; it has no effect when reading |
| from regular files. |
| If <code class="code">read</code> times out, <code class="code">read</code> saves any partial input read into |
| the specified variable <var class="var">name</var>. |
| If <var class="var">timeout</var> is 0, <code class="code">read</code> returns immediately, without trying to |
| read any data. |
| The exit status is 0 if input is available on the specified file descriptor, |
| or the read will return EOF, |
| non-zero otherwise. |
| The exit status is greater than 128 if the timeout is exceeded. |
| </p> |
| </dd> |
| <dt><code class="code">-u <var class="var">fd</var></code></dt> |
| <dd><p>Read input from file descriptor <var class="var">fd</var>. |
| </p></dd> |
| </dl> |
| |
| <p>If no <var class="var">name</var>s are supplied, the line read, |
| without the ending delimiter but otherwise unmodified, |
| is assigned to the |
| variable <code class="env">REPLY</code>. |
| The exit status is zero, unless end-of-file is encountered, <code class="code">read</code> |
| times out (in which case the status is greater than 128), |
| a variable assignment error (such as assigning to a readonly variable) occurs, |
| or an invalid file descriptor is supplied as the argument to <samp class="option">-u</samp>. |
| </p> |
| </dd> |
| <dt><a id="index-readarray"></a><span><code class="code">readarray</code><a class="copiable-link" href="#index-readarray"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">readarray [-d <var class="var">delim</var>] [-n <var class="var">count</var>] [-O <var class="var">origin</var>] [-s <var class="var">count</var>] |
| [-t] [-u <var class="var">fd</var>] [-C <var class="var">callback</var>] [-c <var class="var">quantum</var>] [<var class="var">array</var>] |
| </pre></div> |
| |
| <p>Read lines from the standard input into the indexed array variable <var class="var">array</var>, |
| or from file descriptor <var class="var">fd</var> |
| if the <samp class="option">-u</samp> option is supplied. |
| </p> |
| <p>A synonym for <code class="code">mapfile</code>. |
| </p> |
| </dd> |
| <dt><a id="index-source"></a><span><code class="code">source</code><a class="copiable-link" href="#index-source"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">source <var class="var">filename</var> |
| </pre></div> |
| |
| <p>A synonym for <code class="code">.</code> (see <a class="pxref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>). |
| </p> |
| </dd> |
| <dt><a id="index-type"></a><span><code class="code">type</code><a class="copiable-link" href="#index-type"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">type [-afptP] [<var class="var">name</var> ...] |
| </pre></div> |
| |
| <p>For each <var class="var">name</var>, indicate how it would be interpreted if used as a |
| command name. |
| </p> |
| <p>If the <samp class="option">-t</samp> option is used, <code class="code">type</code> prints a single word |
| which is one of ‘<samp class="samp">alias</samp>’, ‘<samp class="samp">function</samp>’, ‘<samp class="samp">builtin</samp>’, |
| ‘<samp class="samp">file</samp>’ or ‘<samp class="samp">keyword</samp>’, |
| if <var class="var">name</var> is an alias, shell function, shell builtin, |
| disk file, or shell reserved word, respectively. |
| If the <var class="var">name</var> is not found, then nothing is printed, and |
| <code class="code">type</code> returns a failure status. |
| </p> |
| <p>If the <samp class="option">-p</samp> option is used, <code class="code">type</code> either returns the name |
| of the disk file that would be executed, or nothing if <samp class="option">-t</samp> |
| would not return ‘<samp class="samp">file</samp>’. |
| </p> |
| <p>The <samp class="option">-P</samp> option forces a path search for each <var class="var">name</var>, even if |
| <samp class="option">-t</samp> would not return ‘<samp class="samp">file</samp>’. |
| </p> |
| <p>If a command is hashed, <samp class="option">-p</samp> and <samp class="option">-P</samp> print the hashed value, |
| which is not necessarily the file that appears first in <code class="code">$PATH</code>. |
| </p> |
| <p>If the <samp class="option">-a</samp> option is used, <code class="code">type</code> returns all of the places |
| that contain an executable named <var class="var">file</var>. |
| This includes aliases and functions, if and only if the <samp class="option">-p</samp> option |
| is not also used. |
| </p> |
| <p>If the <samp class="option">-f</samp> option is used, <code class="code">type</code> does not attempt to find |
| shell functions, as with the <code class="code">command</code> builtin. |
| </p> |
| <p>The return status is zero if all of the <var class="var">name</var>s are found, non-zero |
| if any are not found. |
| </p> |
| </dd> |
| <dt><a id="index-typeset"></a><span><code class="code">typeset</code><a class="copiable-link" href="#index-typeset"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">typeset [-afFgrxilnrtux] [-p] [<var class="var">name</var>[=<var class="var">value</var>] ...] |
| </pre></div> |
| |
| <p>The <code class="code">typeset</code> command is supplied for compatibility with the Korn |
| shell. |
| It is a synonym for the <code class="code">declare</code> builtin command. |
| </p> |
| </dd> |
| <dt><a id="index-ulimit"></a><span><code class="code">ulimit</code><a class="copiable-link" href="#index-ulimit"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">ulimit [-HS] -a |
| ulimit [-HS] [-bcdefiklmnpqrstuvxPRT] [<var class="var">limit</var>] |
| </pre></div> |
| |
| <p><code class="code">ulimit</code> provides control over the resources available to processes |
| started by the shell, on systems that allow such control. If an |
| option is given, it is interpreted as follows: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">-S</code></dt> |
| <dd><p>Change and report the soft limit associated with a resource. |
| </p> |
| </dd> |
| <dt><code class="code">-H</code></dt> |
| <dd><p>Change and report the hard limit associated with a resource. |
| </p> |
| </dd> |
| <dt><code class="code">-a</code></dt> |
| <dd><p>All current limits are reported; no limits are set. |
| </p> |
| </dd> |
| <dt><code class="code">-b</code></dt> |
| <dd><p>The maximum socket buffer size. |
| </p> |
| </dd> |
| <dt><code class="code">-c</code></dt> |
| <dd><p>The maximum size of core files created. |
| </p> |
| </dd> |
| <dt><code class="code">-d</code></dt> |
| <dd><p>The maximum size of a process’s data segment. |
| </p> |
| </dd> |
| <dt><code class="code">-e</code></dt> |
| <dd><p>The maximum scheduling priority ("nice"). |
| </p> |
| </dd> |
| <dt><code class="code">-f</code></dt> |
| <dd><p>The maximum size of files written by the shell and its children. |
| </p> |
| </dd> |
| <dt><code class="code">-i</code></dt> |
| <dd><p>The maximum number of pending signals. |
| </p> |
| </dd> |
| <dt><code class="code">-k</code></dt> |
| <dd><p>The maximum number of kqueues that may be allocated. |
| </p> |
| </dd> |
| <dt><code class="code">-l</code></dt> |
| <dd><p>The maximum size that may be locked into memory. |
| </p> |
| </dd> |
| <dt><code class="code">-m</code></dt> |
| <dd><p>The maximum resident set size (many systems do not honor this limit). |
| </p> |
| </dd> |
| <dt><code class="code">-n</code></dt> |
| <dd><p>The maximum number of open file descriptors (most systems do not |
| allow this value to be set). |
| </p> |
| </dd> |
| <dt><code class="code">-p</code></dt> |
| <dd><p>The pipe buffer size. |
| </p> |
| </dd> |
| <dt><code class="code">-q</code></dt> |
| <dd><p>The maximum number of bytes in <small class="sc">POSIX</small> message queues. |
| </p> |
| </dd> |
| <dt><code class="code">-r</code></dt> |
| <dd><p>The maximum real-time scheduling priority. |
| </p> |
| </dd> |
| <dt><code class="code">-s</code></dt> |
| <dd><p>The maximum stack size. |
| </p> |
| </dd> |
| <dt><code class="code">-t</code></dt> |
| <dd><p>The maximum amount of cpu time in seconds. |
| </p> |
| </dd> |
| <dt><code class="code">-u</code></dt> |
| <dd><p>The maximum number of processes available to a single user. |
| </p> |
| </dd> |
| <dt><code class="code">-v</code></dt> |
| <dd><p>The maximum amount of virtual memory available to the shell, and, on |
| some systems, to its children. |
| </p> |
| </dd> |
| <dt><code class="code">-x</code></dt> |
| <dd><p>The maximum number of file locks. |
| </p> |
| </dd> |
| <dt><code class="code">-P</code></dt> |
| <dd><p>The maximum number of pseudoterminals. |
| </p> |
| </dd> |
| <dt><code class="code">-R</code></dt> |
| <dd><p>The maximum time a real-time process can run before blocking, in microseconds. |
| </p> |
| </dd> |
| <dt><code class="code">-T</code></dt> |
| <dd><p>The maximum number of threads. |
| </p></dd> |
| </dl> |
| |
| <p>If <var class="var">limit</var> is given, and the <samp class="option">-a</samp> option is not used, |
| <var class="var">limit</var> is the new value of the specified resource. |
| The special <var class="var">limit</var> values <code class="code">hard</code>, <code class="code">soft</code>, and |
| <code class="code">unlimited</code> stand for the current hard limit, the current soft limit, |
| and no limit, respectively. |
| A hard limit cannot be increased by a non-root user once it is set; |
| a soft limit may be increased up to the value of the hard limit. |
| Otherwise, the current value of the soft limit for the specified resource |
| is printed, unless the <samp class="option">-H</samp> option is supplied. |
| When more than one |
| resource is specified, the limit name and unit, if appropriate, |
| are printed before the value. |
| When setting new limits, if neither <samp class="option">-H</samp> nor <samp class="option">-S</samp> is supplied, |
| both the hard and soft limits are set. |
| If no option is given, then <samp class="option">-f</samp> is assumed. Values are in 1024-byte |
| increments, except for |
| <samp class="option">-t</samp>, which is in seconds; |
| <samp class="option">-R</samp>, which is in microseconds; |
| <samp class="option">-p</samp>, which is in units of 512-byte blocks; |
| <samp class="option">-P</samp>, |
| <samp class="option">-T</samp>, |
| <samp class="option">-b</samp>, |
| <samp class="option">-k</samp>, |
| <samp class="option">-n</samp> and <samp class="option">-u</samp>, which are unscaled values; |
| and, when in <small class="sc">POSIX</small> Mode (see <a class="pxref" href="#Bash-POSIX-Mode">Bash POSIX Mode</a>), |
| <samp class="option">-c</samp> and <samp class="option">-f</samp>, which are in 512-byte increments. |
| </p> |
| <p>The return status is zero unless an invalid option or argument is supplied, |
| or an error occurs while setting a new limit. |
| </p> |
| </dd> |
| <dt><a id="index-unalias"></a><span><code class="code">unalias</code><a class="copiable-link" href="#index-unalias"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">unalias [-a] [<var class="var">name</var> ... ] |
| </pre></div> |
| |
| <p>Remove each <var class="var">name</var> from the list of aliases. If <samp class="option">-a</samp> is |
| supplied, all aliases are removed. |
| Aliases are described in <a class="ref" href="#Aliases">Aliases</a>. |
| </p></dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Modifying-Shell-Behavior"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Special-Builtins" accesskey="n" rel="next">Special Builtins</a>, Previous: <a href="#Bash-Builtins" accesskey="p" rel="prev">Bash Builtin Commands</a>, Up: <a href="#Shell-Builtin-Commands" accesskey="u" rel="up">Shell Builtin Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Modifying-Shell-Behavior-1"><span>4.3 Modifying Shell Behavior<a class="copiable-link" href="#Modifying-Shell-Behavior-1"> ¶</a></span></h3> |
| |
| |
| <ul class="mini-toc"> |
| <li><a href="#The-Set-Builtin" accesskey="1">The Set Builtin</a></li> |
| <li><a href="#The-Shopt-Builtin" accesskey="2">The Shopt Builtin</a></li> |
| </ul> |
| <hr> |
| <div class="subsection-level-extent" id="The-Set-Builtin"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#The-Shopt-Builtin" accesskey="n" rel="next">The Shopt Builtin</a>, Up: <a href="#Modifying-Shell-Behavior" accesskey="u" rel="up">Modifying Shell Behavior</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="The-Set-Builtin-1"><span>4.3.1 The Set Builtin<a class="copiable-link" href="#The-Set-Builtin-1"> ¶</a></span></h4> |
| |
| <p>This builtin is so complicated that it deserves its own section. <code class="code">set</code> |
| allows you to change the values of shell options and set the positional |
| parameters, or to display the names and values of shell variables. |
| </p> |
| <dl class="table"> |
| <dt><a id="index-set"></a><span><code class="code">set</code><a class="copiable-link" href="#index-set"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">set [-abefhkmnptuvxBCEHPT] [-o <var class="var">option-name</var>] [--] [-] [<var class="var">argument</var> ...] |
| set [+abefhkmnptuvxBCEHPT] [+o <var class="var">option-name</var>] [--] [-] [<var class="var">argument</var> ...] |
| </pre></div> |
| |
| <p>If no options or arguments are supplied, <code class="code">set</code> displays the names |
| and values of all shell variables and functions, sorted according to the |
| current locale, in a format that may be reused as input |
| for setting or resetting the currently-set variables. |
| Read-only variables cannot be reset. |
| In <small class="sc">POSIX</small> mode, only shell variables are listed. |
| </p> |
| <p>When options are supplied, they set or unset shell attributes. |
| Options, if specified, have the following meanings: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">-a</code></dt> |
| <dd><p>Each variable or function that is created or modified is given the |
| export attribute and marked for export to the environment of |
| subsequent commands. |
| </p> |
| </dd> |
| <dt><code class="code">-b</code></dt> |
| <dd><p>Cause the status of terminated background jobs to be reported |
| immediately, rather than before printing the next primary prompt. |
| </p> |
| </dd> |
| <dt><code class="code">-e</code></dt> |
| <dd><p>Exit immediately if |
| a pipeline (see <a class="pxref" href="#Pipelines">Pipelines</a>), which may consist of a single simple command |
| (see <a class="pxref" href="#Simple-Commands">Simple Commands</a>), |
| a list (see <a class="pxref" href="#Lists">Lists of Commands</a>), |
| or a compound command (see <a class="pxref" href="#Compound-Commands">Compound Commands</a>) |
| returns a non-zero status. |
| The shell does not exit if the command that fails is part of the |
| command list immediately following a <code class="code">while</code> or <code class="code">until</code> keyword, |
| part of the test in an <code class="code">if</code> statement, |
| part of any command executed in a <code class="code">&&</code> or <code class="code">||</code> list except |
| the command following the final <code class="code">&&</code> or <code class="code">||</code>, |
| any command in a pipeline but the last, |
| or if the command’s return status is being inverted with <code class="code">!</code>. |
| If a compound command other than a subshell |
| returns a non-zero status because a command failed |
| while <samp class="option">-e</samp> was being ignored, the shell does not exit. |
| A trap on <code class="code">ERR</code>, if set, is executed before the shell exits. |
| </p> |
| <p>This option applies to the shell environment and each subshell environment |
| separately (see <a class="pxref" href="#Command-Execution-Environment">Command Execution Environment</a>), and may cause |
| subshells to exit before executing all the commands in the subshell. |
| </p> |
| <p>If a compound command or shell function executes in a context where |
| <samp class="option">-e</samp> is being ignored, |
| none of the commands executed within the compound command or function body |
| will be affected by the <samp class="option">-e</samp> setting, even if <samp class="option">-e</samp> is set |
| and a command returns a failure status. |
| If a compound command or shell function sets <samp class="option">-e</samp> while executing in |
| a context where <samp class="option">-e</samp> is ignored, that setting will not have any |
| effect until the compound command or the command containing the function |
| call completes. |
| </p> |
| </dd> |
| <dt><code class="code">-f</code></dt> |
| <dd><p>Disable filename expansion (globbing). |
| </p> |
| </dd> |
| <dt><code class="code">-h</code></dt> |
| <dd><p>Locate and remember (hash) commands as they are looked up for execution. |
| This option is enabled by default. |
| </p> |
| </dd> |
| <dt><code class="code">-k</code></dt> |
| <dd><p>All arguments in the form of assignment statements are placed |
| in the environment for a command, not just those that precede |
| the command name. |
| </p> |
| </dd> |
| <dt><code class="code">-m</code></dt> |
| <dd><p>Job control is enabled (see <a class="pxref" href="#Job-Control">Job Control</a>). |
| All processes run in a separate process group. |
| When a background job completes, the shell prints a line |
| containing its exit status. |
| </p> |
| </dd> |
| <dt><code class="code">-n</code></dt> |
| <dd><p>Read commands but do not execute them. |
| This may be used to check a script for syntax errors. |
| This option is ignored by interactive shells. |
| </p> |
| </dd> |
| <dt><code class="code">-o <var class="var">option-name</var></code></dt> |
| <dd> |
| <p>Set the option corresponding to <var class="var">option-name</var>: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">allexport</code></dt> |
| <dd><p>Same as <code class="code">-a</code>. |
| </p> |
| </dd> |
| <dt><code class="code">braceexpand</code></dt> |
| <dd><p>Same as <code class="code">-B</code>. |
| </p> |
| </dd> |
| <dt><code class="code">emacs</code></dt> |
| <dd><p>Use an <code class="code">emacs</code>-style line editing interface (see <a class="pxref" href="#Command-Line-Editing">Command Line Editing</a>). |
| This also affects the editing interface used for <code class="code">read -e</code>. |
| </p> |
| </dd> |
| <dt><code class="code">errexit</code></dt> |
| <dd><p>Same as <code class="code">-e</code>. |
| </p> |
| </dd> |
| <dt><code class="code">errtrace</code></dt> |
| <dd><p>Same as <code class="code">-E</code>. |
| </p> |
| </dd> |
| <dt><code class="code">functrace</code></dt> |
| <dd><p>Same as <code class="code">-T</code>. |
| </p> |
| </dd> |
| <dt><code class="code">hashall</code></dt> |
| <dd><p>Same as <code class="code">-h</code>. |
| </p> |
| </dd> |
| <dt><code class="code">histexpand</code></dt> |
| <dd><p>Same as <code class="code">-H</code>. |
| </p> |
| </dd> |
| <dt><code class="code">history</code></dt> |
| <dd><p>Enable command history, as described in <a class="ref" href="#Bash-History-Facilities">Bash History Facilities</a>. |
| This option is on by default in interactive shells. |
| </p> |
| </dd> |
| <dt><code class="code">ignoreeof</code></dt> |
| <dd><p>An interactive shell will not exit upon reading EOF. |
| </p> |
| </dd> |
| <dt><code class="code">keyword</code></dt> |
| <dd><p>Same as <code class="code">-k</code>. |
| </p> |
| </dd> |
| <dt><code class="code">monitor</code></dt> |
| <dd><p>Same as <code class="code">-m</code>. |
| </p> |
| </dd> |
| <dt><code class="code">noclobber</code></dt> |
| <dd><p>Same as <code class="code">-C</code>. |
| </p> |
| </dd> |
| <dt><code class="code">noexec</code></dt> |
| <dd><p>Same as <code class="code">-n</code>. |
| </p> |
| </dd> |
| <dt><code class="code">noglob</code></dt> |
| <dd><p>Same as <code class="code">-f</code>. |
| </p> |
| </dd> |
| <dt><code class="code">nolog</code></dt> |
| <dd><p>Currently ignored. |
| </p> |
| </dd> |
| <dt><code class="code">notify</code></dt> |
| <dd><p>Same as <code class="code">-b</code>. |
| </p> |
| </dd> |
| <dt><code class="code">nounset</code></dt> |
| <dd><p>Same as <code class="code">-u</code>. |
| </p> |
| </dd> |
| <dt><code class="code">onecmd</code></dt> |
| <dd><p>Same as <code class="code">-t</code>. |
| </p> |
| </dd> |
| <dt><code class="code">physical</code></dt> |
| <dd><p>Same as <code class="code">-P</code>. |
| </p> |
| </dd> |
| <dt><code class="code">pipefail</code></dt> |
| <dd><p>If set, the return value of a pipeline is the value of the last |
| (rightmost) command to exit with a non-zero status, or zero if all |
| commands in the pipeline exit successfully. |
| This option is disabled by default. |
| </p> |
| </dd> |
| <dt><code class="code">posix</code></dt> |
| <dd><p>Change the behavior of Bash where the default operation differs |
| from the <small class="sc">POSIX</small> standard to match the standard |
| (see <a class="pxref" href="#Bash-POSIX-Mode">Bash POSIX Mode</a>). |
| This is intended to make Bash behave as a strict superset of that |
| standard. |
| </p> |
| </dd> |
| <dt><code class="code">privileged</code></dt> |
| <dd><p>Same as <code class="code">-p</code>. |
| </p> |
| </dd> |
| <dt><code class="code">verbose</code></dt> |
| <dd><p>Same as <code class="code">-v</code>. |
| </p> |
| </dd> |
| <dt><code class="code">vi</code></dt> |
| <dd><p>Use a <code class="code">vi</code>-style line editing interface. |
| This also affects the editing interface used for <code class="code">read -e</code>. |
| </p> |
| </dd> |
| <dt><code class="code">xtrace</code></dt> |
| <dd><p>Same as <code class="code">-x</code>. |
| </p></dd> |
| </dl> |
| |
| </dd> |
| <dt><code class="code">-p</code></dt> |
| <dd><p>Turn on privileged mode. |
| In this mode, the <code class="env">$BASH_ENV</code> and <code class="env">$ENV</code> files are not |
| processed, shell functions are not inherited from the environment, |
| and the <code class="env">SHELLOPTS</code>, <code class="env">BASHOPTS</code>, <code class="env">CDPATH</code> and <code class="env">GLOBIGNORE</code> |
| variables, if they appear in the environment, are ignored. |
| If the shell is started with the effective user (group) id not equal to the |
| real user (group) id, and the <samp class="option">-p</samp> option is not supplied, these actions |
| are taken and the effective user id is set to the real user id. |
| If the <samp class="option">-p</samp> option is supplied at startup, the effective user id is |
| not reset. |
| Turning this option off causes the effective user |
| and group ids to be set to the real user and group ids. |
| </p> |
| </dd> |
| <dt><code class="code">-r</code></dt> |
| <dd><p>Enable restricted shell mode. |
| This option cannot be unset once it has been set. |
| </p> |
| </dd> |
| <dt><code class="code">-t</code></dt> |
| <dd><p>Exit after reading and executing one command. |
| </p> |
| </dd> |
| <dt><code class="code">-u</code></dt> |
| <dd><p>Treat unset variables and parameters other than the special parameters |
| ‘<samp class="samp">@</samp>’ or ‘<samp class="samp">*</samp>’, |
| or array variables subscripted with ‘<samp class="samp">@</samp>’ or ‘<samp class="samp">*</samp>’, |
| as an error when performing parameter expansion. |
| An error message will be written to the standard error, and a non-interactive |
| shell will exit. |
| </p> |
| </dd> |
| <dt><code class="code">-v</code></dt> |
| <dd><p>Print shell input lines as they are read. |
| </p> |
| </dd> |
| <dt><code class="code">-x</code></dt> |
| <dd><p>Print a trace of simple commands, <code class="code">for</code> commands, <code class="code">case</code> |
| commands, <code class="code">select</code> commands, and arithmetic <code class="code">for</code> commands |
| and their arguments or associated word lists after they are |
| expanded and before they are executed. The value of the <code class="env">PS4</code> |
| variable is expanded and the resultant value is printed before |
| the command and its expanded arguments. |
| </p> |
| </dd> |
| <dt><code class="code">-B</code></dt> |
| <dd><p>The shell will perform brace expansion (see <a class="pxref" href="#Brace-Expansion">Brace Expansion</a>). |
| This option is on by default. |
| </p> |
| </dd> |
| <dt><code class="code">-C</code></dt> |
| <dd><p>Prevent output redirection using ‘<samp class="samp">></samp>’, ‘<samp class="samp">>&</samp>’, and ‘<samp class="samp"><></samp>’ |
| from overwriting existing files. |
| </p> |
| </dd> |
| <dt><code class="code">-E</code></dt> |
| <dd><p>If set, any trap on <code class="code">ERR</code> is inherited by shell functions, command |
| substitutions, and commands executed in a subshell environment. |
| The <code class="code">ERR</code> trap is normally not inherited in such cases. |
| </p> |
| </dd> |
| <dt><code class="code">-H</code></dt> |
| <dd><p>Enable ‘<samp class="samp">!</samp>’ style history substitution (see <a class="pxref" href="#History-Interaction">History Expansion</a>). |
| This option is on by default for interactive shells. |
| </p> |
| </dd> |
| <dt><code class="code">-P</code></dt> |
| <dd><p>If set, do not resolve symbolic links when performing commands such as |
| <code class="code">cd</code> which change the current directory. The physical directory |
| is used instead. By default, Bash follows |
| the logical chain of directories when performing commands |
| which change the current directory. |
| </p> |
| <p>For example, if <samp class="file">/usr/sys</samp> is a symbolic link to <samp class="file">/usr/local/sys</samp> |
| then: |
| </p><div class="example"> |
| <pre class="example-preformatted">$ cd /usr/sys; echo $PWD |
| /usr/sys |
| $ cd ..; pwd |
| /usr |
| </pre></div> |
| |
| <p>If <code class="code">set -P</code> is on, then: |
| </p><div class="example"> |
| <pre class="example-preformatted">$ cd /usr/sys; echo $PWD |
| /usr/local/sys |
| $ cd ..; pwd |
| /usr/local |
| </pre></div> |
| |
| </dd> |
| <dt><code class="code">-T</code></dt> |
| <dd><p>If set, any trap on <code class="code">DEBUG</code> and <code class="code">RETURN</code> are inherited by |
| shell functions, command substitutions, and commands executed |
| in a subshell environment. |
| The <code class="code">DEBUG</code> and <code class="code">RETURN</code> traps are normally not inherited |
| in such cases. |
| </p> |
| </dd> |
| <dt><code class="code">--</code></dt> |
| <dd><p>If no arguments follow this option, then the positional parameters are |
| unset. Otherwise, the positional parameters are set to the |
| <var class="var">arguments</var>, even if some of them begin with a ‘<samp class="samp">-</samp>’. |
| </p> |
| </dd> |
| <dt><code class="code">-</code></dt> |
| <dd><p>Signal the end of options, cause all remaining <var class="var">arguments</var> |
| to be assigned to the positional parameters. The <samp class="option">-x</samp> |
| and <samp class="option">-v</samp> options are turned off. |
| If there are no arguments, the positional parameters remain unchanged. |
| </p></dd> |
| </dl> |
| |
| <p>Using ‘<samp class="samp">+</samp>’ rather than ‘<samp class="samp">-</samp>’ causes these options to be |
| turned off. The options can also be used upon invocation of the |
| shell. The current set of options may be found in <code class="code">$-</code>. |
| </p> |
| <p>The remaining N <var class="var">arguments</var> are positional parameters and are |
| assigned, in order, to <code class="code">$1</code>, <code class="code">$2</code>, … <code class="code">$N</code>. |
| The special parameter <code class="code">#</code> is set to N. |
| </p> |
| <p>The return status is always zero unless an invalid option is supplied. |
| </p></dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="The-Shopt-Builtin"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#The-Set-Builtin" accesskey="p" rel="prev">The Set Builtin</a>, Up: <a href="#Modifying-Shell-Behavior" accesskey="u" rel="up">Modifying Shell Behavior</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="The-Shopt-Builtin-1"><span>4.3.2 The Shopt Builtin<a class="copiable-link" href="#The-Shopt-Builtin-1"> ¶</a></span></h4> |
| |
| <p>This builtin allows you to change additional shell optional behavior. |
| </p> |
| <dl class="table"> |
| <dt><a id="index-shopt"></a><span><code class="code">shopt</code><a class="copiable-link" href="#index-shopt"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">shopt [-pqsu] [-o] [<var class="var">optname</var> ...] |
| </pre></div> |
| |
| <p>Toggle the values of settings controlling optional shell behavior. |
| The settings can be either those listed below, or, if the |
| <samp class="option">-o</samp> option is used, those available with the <samp class="option">-o</samp> |
| option to the <code class="code">set</code> builtin command (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>). |
| With no options, or with the <samp class="option">-p</samp> option, a list of all settable |
| options is displayed, with an indication of whether or not each is set; |
| if <var class="var">optname</var>s are supplied, the output is restricted to those options. |
| The <samp class="option">-p</samp> option causes output to be displayed in a form that |
| may be reused as input. |
| Other options have the following meanings: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">-s</code></dt> |
| <dd><p>Enable (set) each <var class="var">optname</var>. |
| </p> |
| </dd> |
| <dt><code class="code">-u</code></dt> |
| <dd><p>Disable (unset) each <var class="var">optname</var>. |
| </p> |
| </dd> |
| <dt><code class="code">-q</code></dt> |
| <dd><p>Suppresses normal output; the return status |
| indicates whether the <var class="var">optname</var> is set or unset. |
| If multiple <var class="var">optname</var> arguments are given with <samp class="option">-q</samp>, |
| the return status is zero if all <var class="var">optname</var>s are enabled; |
| non-zero otherwise. |
| </p> |
| </dd> |
| <dt><code class="code">-o</code></dt> |
| <dd><p>Restricts the values of |
| <var class="var">optname</var> to be those defined for the <samp class="option">-o</samp> option to the |
| <code class="code">set</code> builtin (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>). |
| </p></dd> |
| </dl> |
| |
| <p>If either <samp class="option">-s</samp> or <samp class="option">-u</samp> |
| is used with no <var class="var">optname</var> arguments, <code class="code">shopt</code> shows only |
| those options which are set or unset, respectively. |
| </p> |
| <p>Unless otherwise noted, the <code class="code">shopt</code> options are disabled (off) |
| by default. |
| </p> |
| <p>The return status when listing options is zero if all <var class="var">optname</var>s |
| are enabled, non-zero otherwise. When setting or unsetting options, |
| the return status is zero unless an <var class="var">optname</var> is not a valid shell |
| option. |
| </p> |
| <p>The list of <code class="code">shopt</code> options is: |
| </p><dl class="table"> |
| <dt><code class="code">assoc_expand_once</code></dt> |
| <dd><p>If set, the shell suppresses multiple evaluation of associative array |
| subscripts during arithmetic expression evaluation, while executing |
| builtins that can perform variable assignments, |
| and while executing builtins that perform array dereferencing. |
| </p> |
| </dd> |
| <dt><code class="code">autocd</code></dt> |
| <dd><p>If set, a command name that is the name of a directory is executed as if |
| it were the argument to the <code class="code">cd</code> command. |
| This option is only used by interactive shells. |
| </p> |
| </dd> |
| <dt><code class="code">cdable_vars</code></dt> |
| <dd><p>If this is set, an argument to the <code class="code">cd</code> builtin command that |
| is not a directory is assumed to be the name of a variable whose |
| value is the directory to change to. |
| </p> |
| </dd> |
| <dt><code class="code">cdspell</code></dt> |
| <dd><p>If set, minor errors in the spelling of a directory component in a |
| <code class="code">cd</code> command will be corrected. |
| The errors checked for are transposed characters, |
| a missing character, and a character too many. |
| If a correction is found, the corrected path is printed, |
| and the command proceeds. |
| This option is only used by interactive shells. |
| </p> |
| </dd> |
| <dt><code class="code">checkhash</code></dt> |
| <dd><p>If this is set, Bash checks that a command found in the hash |
| table exists before trying to execute it. If a hashed command no |
| longer exists, a normal path search is performed. |
| </p> |
| </dd> |
| <dt><code class="code">checkjobs</code></dt> |
| <dd><p>If set, Bash lists the status of any stopped and running jobs before |
| exiting an interactive shell. If any jobs are running, this causes |
| the exit to be deferred until a second exit is attempted without an |
| intervening command (see <a class="pxref" href="#Job-Control">Job Control</a>). |
| The shell always postpones exiting if any jobs are stopped. |
| </p> |
| </dd> |
| <dt><code class="code">checkwinsize</code></dt> |
| <dd><p>If set, Bash checks the window size after each external (non-builtin) |
| command and, if necessary, updates the values of |
| <code class="env">LINES</code> and <code class="env">COLUMNS</code>. |
| This option is enabled by default. |
| </p> |
| </dd> |
| <dt><code class="code">cmdhist</code></dt> |
| <dd><p>If set, Bash |
| attempts to save all lines of a multiple-line |
| command in the same history entry. This allows |
| easy re-editing of multi-line commands. |
| This option is enabled by default, but only has an effect if command |
| history is enabled (see <a class="pxref" href="#Bash-History-Facilities">Bash History Facilities</a>). |
| </p> |
| </dd> |
| <dt><code class="code">compat31</code></dt> |
| <dt><code class="code">compat32</code></dt> |
| <dt><code class="code">compat40</code></dt> |
| <dt><code class="code">compat41</code></dt> |
| <dt><code class="code">compat42</code></dt> |
| <dt><code class="code">compat43</code></dt> |
| <dt><code class="code">compat44</code></dt> |
| <dd><p>These control aspects of the shell’s compatibility mode |
| (see <a class="pxref" href="#Shell-Compatibility-Mode">Shell Compatibility Mode</a>). |
| </p> |
| </dd> |
| <dt><code class="code">complete_fullquote</code></dt> |
| <dd><p>If set, Bash |
| quotes all shell metacharacters in filenames and directory names when |
| performing completion. |
| If not set, Bash |
| removes metacharacters such as the dollar sign from the set of |
| characters that will be quoted in completed filenames |
| when these metacharacters appear in shell variable references in words to be |
| completed. |
| This means that dollar signs in variable names that expand to directories |
| will not be quoted; |
| however, any dollar signs appearing in filenames will not be quoted, either. |
| This is active only when bash is using backslashes to quote completed |
| filenames. |
| This variable is set by default, which is the default Bash behavior in |
| versions through 4.2. |
| </p> |
| </dd> |
| <dt><code class="code">direxpand</code></dt> |
| <dd><p>If set, Bash |
| replaces directory names with the results of word expansion when performing |
| filename completion. This changes the contents of the Readline editing |
| buffer. |
| If not set, Bash attempts to preserve what the user typed. |
| </p> |
| </dd> |
| <dt><code class="code">dirspell</code></dt> |
| <dd><p>If set, Bash |
| attempts spelling correction on directory names during word completion |
| if the directory name initially supplied does not exist. |
| </p> |
| </dd> |
| <dt><code class="code">dotglob</code></dt> |
| <dd><p>If set, Bash includes filenames beginning with a ‘.’ in |
| the results of filename expansion. |
| The filenames ‘<samp class="samp">.</samp>’ and ‘<samp class="samp">..</samp>’ must always be matched explicitly, |
| even if <code class="code">dotglob</code> is set. |
| </p> |
| </dd> |
| <dt><code class="code">execfail</code></dt> |
| <dd><p>If this is set, a non-interactive shell will not exit if |
| it cannot execute the file specified as an argument to the <code class="code">exec</code> |
| builtin command. An interactive shell does not exit if <code class="code">exec</code> |
| fails. |
| </p> |
| </dd> |
| <dt><code class="code">expand_aliases</code></dt> |
| <dd><p>If set, aliases are expanded as described below under Aliases, |
| <a class="ref" href="#Aliases">Aliases</a>. |
| This option is enabled by default for interactive shells. |
| </p> |
| </dd> |
| <dt><code class="code">extdebug</code></dt> |
| <dd><p>If set at shell invocation, |
| or in a shell startup file, |
| arrange to execute the debugger profile |
| before the shell starts, identical to the <samp class="option">--debugger</samp> option. |
| If set after invocation, behavior intended for use by debuggers is enabled: |
| </p> |
| <ol class="enumerate"> |
| <li> The <samp class="option">-F</samp> option to the <code class="code">declare</code> builtin (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>) |
| displays the source file name and line number corresponding to each function |
| name supplied as an argument. |
| |
| </li><li> If the command run by the <code class="code">DEBUG</code> trap returns a non-zero value, the |
| next command is skipped and not executed. |
| |
| </li><li> If the command run by the <code class="code">DEBUG</code> trap returns a value of 2, and the |
| shell is executing in a subroutine (a shell function or a shell script |
| executed by the <code class="code">.</code> or <code class="code">source</code> builtins), the shell simulates |
| a call to <code class="code">return</code>. |
| |
| </li><li> <code class="code">BASH_ARGC</code> and <code class="code">BASH_ARGV</code> are updated as described in their |
| descriptions (see <a class="pxref" href="#Bash-Variables">Bash Variables</a>). |
| |
| </li><li> Function tracing is enabled: command substitution, shell functions, and |
| subshells invoked with <code class="code">( <var class="var">command</var> )</code> inherit the |
| <code class="code">DEBUG</code> and <code class="code">RETURN</code> traps. |
| |
| </li><li> Error tracing is enabled: command substitution, shell functions, and |
| subshells invoked with <code class="code">( <var class="var">command</var> )</code> inherit the |
| <code class="code">ERR</code> trap. |
| </li></ol> |
| |
| </dd> |
| <dt><code class="code">extglob</code></dt> |
| <dd><p>If set, the extended pattern matching features described above |
| (see <a class="pxref" href="#Pattern-Matching">Pattern Matching</a>) are enabled. |
| </p> |
| </dd> |
| <dt><code class="code">extquote</code></dt> |
| <dd><p>If set, <code class="code">$'<var class="var">string</var>'</code> and <code class="code">$"<var class="var">string</var>"</code> quoting is |
| performed within <code class="code">${<var class="var">parameter</var>}</code> expansions |
| enclosed in double quotes. This option is enabled by default. |
| </p> |
| </dd> |
| <dt><code class="code">failglob</code></dt> |
| <dd><p>If set, patterns which fail to match filenames during filename expansion |
| result in an expansion error. |
| </p> |
| </dd> |
| <dt><code class="code">force_fignore</code></dt> |
| <dd><p>If set, the suffixes specified by the <code class="env">FIGNORE</code> shell variable |
| cause words to be ignored when performing word completion even if |
| the ignored words are the only possible completions. |
| See <a class="xref" href="#Bash-Variables">Bash Variables</a>, for a description of <code class="env">FIGNORE</code>. |
| This option is enabled by default. |
| </p> |
| </dd> |
| <dt><code class="code">globasciiranges</code></dt> |
| <dd><p>If set, range expressions used in pattern matching bracket expressions |
| (see <a class="pxref" href="#Pattern-Matching">Pattern Matching</a>) |
| behave as if in the traditional C locale when performing |
| comparisons. That is, the current locale’s collating sequence |
| is not taken into account, so |
| ‘<samp class="samp">b</samp>’ will not collate between ‘<samp class="samp">A</samp>’ and ‘<samp class="samp">B</samp>’, |
| and upper-case and lower-case ASCII characters will collate together. |
| </p> |
| </dd> |
| <dt><code class="code">globskipdots</code></dt> |
| <dd><p>If set, filename expansion will never match the filenames |
| ‘<samp class="samp">.</samp>’ and ‘<samp class="samp">..</samp>’, |
| even if the pattern begins with a ‘<samp class="samp">.</samp>’. |
| This option is enabled by default. |
| </p> |
| </dd> |
| <dt><code class="code">globstar</code></dt> |
| <dd><p>If set, the pattern ‘<samp class="samp">**</samp>’ used in a filename expansion context will |
| match all files and zero or more directories and subdirectories. |
| If the pattern is followed by a ‘<samp class="samp">/</samp>’, only directories and |
| subdirectories match. |
| </p> |
| </dd> |
| <dt><code class="code">gnu_errfmt</code></dt> |
| <dd><p>If set, shell error messages are written in the standard <small class="sc">GNU</small> error |
| message format. |
| </p> |
| </dd> |
| <dt><code class="code">histappend</code></dt> |
| <dd><p>If set, the history list is appended to the file named by the value |
| of the <code class="env">HISTFILE</code> |
| variable when the shell exits, rather than overwriting the file. |
| </p> |
| </dd> |
| <dt><code class="code">histreedit</code></dt> |
| <dd><p>If set, and Readline |
| is being used, a user is given the opportunity to re-edit a |
| failed history substitution. |
| </p> |
| </dd> |
| <dt><code class="code">histverify</code></dt> |
| <dd><p>If set, and Readline |
| is being used, the results of history substitution are not immediately |
| passed to the shell parser. Instead, the resulting line is loaded into |
| the Readline editing buffer, allowing further modification. |
| </p> |
| </dd> |
| <dt><code class="code">hostcomplete</code></dt> |
| <dd><p>If set, and Readline is being used, Bash will attempt to perform |
| hostname completion when a word containing a ‘<samp class="samp">@</samp>’ is being |
| completed (see <a class="pxref" href="#Commands-For-Completion">Letting Readline Type For You</a>). This option is enabled |
| by default. |
| </p> |
| </dd> |
| <dt><code class="code">huponexit</code></dt> |
| <dd><p>If set, Bash will send <code class="code">SIGHUP</code> to all jobs when an interactive |
| login shell exits (see <a class="pxref" href="#Signals">Signals</a>). |
| </p> |
| </dd> |
| <dt><code class="code">inherit_errexit</code></dt> |
| <dd><p>If set, command substitution inherits the value of the <code class="code">errexit</code> option, |
| instead of unsetting it in the subshell environment. |
| This option is enabled when <small class="sc">POSIX</small> mode is enabled. |
| </p> |
| </dd> |
| <dt><code class="code">interactive_comments</code></dt> |
| <dd><p>Allow a word beginning with ‘<samp class="samp">#</samp>’ |
| to cause that word and all remaining characters on that |
| line to be ignored in an interactive shell. |
| This option is enabled by default. |
| </p> |
| </dd> |
| <dt><code class="code">lastpipe</code></dt> |
| <dd><p>If set, and job control is not active, the shell runs the last command of |
| a pipeline not executed in the background in the current shell environment. |
| </p> |
| </dd> |
| <dt><code class="code">lithist</code></dt> |
| <dd><p>If enabled, and the <code class="code">cmdhist</code> |
| option is enabled, multi-line commands are saved to the history with |
| embedded newlines rather than using semicolon separators where possible. |
| </p> |
| </dd> |
| <dt><code class="code">localvar_inherit</code></dt> |
| <dd><p>If set, local variables inherit the value and attributes of a variable of |
| the same name that exists at a previous scope before any new value is |
| assigned. The <code class="code">nameref</code> attribute is not inherited. |
| </p> |
| </dd> |
| <dt><code class="code">localvar_unset</code></dt> |
| <dd><p>If set, calling <code class="code">unset</code> on local variables in previous function scopes |
| marks them so subsequent lookups find them unset until that function |
| returns. This is identical to the behavior of unsetting local variables |
| at the current function scope. |
| </p> |
| </dd> |
| <dt><code class="code">login_shell</code></dt> |
| <dd><p>The shell sets this option if it is started as a login shell |
| (see <a class="pxref" href="#Invoking-Bash">Invoking Bash</a>). |
| The value may not be changed. |
| </p> |
| </dd> |
| <dt><code class="code">mailwarn</code></dt> |
| <dd><p>If set, and a file that Bash is checking for mail has been |
| accessed since the last time it was checked, the message |
| <code class="code">"The mail in <var class="var">mailfile</var> has been read"</code> is displayed. |
| </p> |
| </dd> |
| <dt><code class="code">no_empty_cmd_completion</code></dt> |
| <dd><p>If set, and Readline is being used, Bash will not attempt to search |
| the <code class="env">PATH</code> for possible completions when completion is attempted |
| on an empty line. |
| </p> |
| </dd> |
| <dt><code class="code">nocaseglob</code></dt> |
| <dd><p>If set, Bash matches filenames in a case-insensitive fashion when |
| performing filename expansion. |
| </p> |
| </dd> |
| <dt><code class="code">nocasematch</code></dt> |
| <dd><p>If set, Bash matches patterns in a case-insensitive fashion when |
| performing matching while executing <code class="code">case</code> or <code class="code">[[</code> |
| conditional commands (see <a class="pxref" href="#Conditional-Constructs">Conditional Constructs</a>, |
| when performing pattern substitution word expansions, |
| or when filtering possible completions as part of programmable completion. |
| </p> |
| </dd> |
| <dt><code class="code">noexpand_translation</code></dt> |
| <dd><p>If set, Bash |
| encloses the translated results of $"..." quoting in single quotes |
| instead of double quotes. |
| If the string is not translated, this has no effect. |
| </p> |
| </dd> |
| <dt><code class="code">nullglob</code></dt> |
| <dd><p>If set, Bash allows filename patterns which match no |
| files to expand to a null string, rather than themselves. |
| </p> |
| </dd> |
| <dt><code class="code">patsub_replacement</code></dt> |
| <dd><p>If set, Bash |
| expands occurrences of ‘<samp class="samp">&</samp>’ in the replacement string of pattern |
| substitution to the text matched by the pattern, as described |
| above (see <a class="pxref" href="#Shell-Parameter-Expansion">Shell Parameter Expansion</a>). |
| This option is enabled by default. |
| </p> |
| </dd> |
| <dt><code class="code">progcomp</code></dt> |
| <dd><p>If set, the programmable completion facilities |
| (see <a class="pxref" href="#Programmable-Completion">Programmable Completion</a>) are enabled. |
| This option is enabled by default. |
| </p> |
| </dd> |
| <dt><code class="code">progcomp_alias</code></dt> |
| <dd><p>If set, and programmable completion is enabled, Bash treats a command |
| name that doesn’t have any completions as a possible alias and attempts |
| alias expansion. If it has an alias, Bash attempts programmable |
| completion using the command word resulting from the expanded alias. |
| </p> |
| </dd> |
| <dt><code class="code">promptvars</code></dt> |
| <dd><p>If set, prompt strings undergo |
| parameter expansion, command substitution, arithmetic |
| expansion, and quote removal after being expanded |
| as described below (see <a class="pxref" href="#Controlling-the-Prompt">Controlling the Prompt</a>). |
| This option is enabled by default. |
| </p> |
| </dd> |
| <dt><code class="code">restricted_shell</code></dt> |
| <dd><p>The shell sets this option if it is started in restricted mode |
| (see <a class="pxref" href="#The-Restricted-Shell">The Restricted Shell</a>). |
| The value may not be changed. |
| This is not reset when the startup files are executed, allowing |
| the startup files to discover whether or not a shell is restricted. |
| </p> |
| </dd> |
| <dt><code class="code">shift_verbose</code></dt> |
| <dd><p>If this is set, the <code class="code">shift</code> |
| builtin prints an error message when the shift count exceeds the |
| number of positional parameters. |
| </p> |
| </dd> |
| <dt><code class="code">sourcepath</code></dt> |
| <dd><p>If set, the <code class="code">.</code> (<code class="code">source</code>) builtin uses the value of <code class="env">PATH</code> |
| to find the directory containing the file supplied as an argument. |
| This option is enabled by default. |
| </p> |
| </dd> |
| <dt><code class="code">varredir_close</code></dt> |
| <dd><p>If set, the shell automatically closes file descriptors assigned using the |
| <code class="code">{varname}</code> redirection syntax (see <a class="pxref" href="#Redirections">Redirections</a>) instead of |
| leaving them open when the command completes. |
| </p> |
| </dd> |
| <dt><code class="code">xpg_echo</code></dt> |
| <dd><p>If set, the <code class="code">echo</code> builtin expands backslash-escape sequences |
| by default. |
| </p> |
| </dd> |
| </dl> |
| </dd> |
| </dl> |
| |
| <hr> |
| </div> |
| </div> |
| <div class="section-level-extent" id="Special-Builtins"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Modifying-Shell-Behavior" accesskey="p" rel="prev">Modifying Shell Behavior</a>, Up: <a href="#Shell-Builtin-Commands" accesskey="u" rel="up">Shell Builtin Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Special-Builtins-1"><span>4.4 Special Builtins<a class="copiable-link" href="#Special-Builtins-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-special-builtin-1"></a> |
| |
| <p>For historical reasons, the <small class="sc">POSIX</small> standard has classified |
| several builtin commands as <em class="emph">special</em>. |
| When Bash is executing in <small class="sc">POSIX</small> mode, the special builtins |
| differ from other builtin commands in three respects: |
| </p> |
| <ol class="enumerate"> |
| <li> Special builtins are found before shell functions during command lookup. |
| |
| </li><li> If a special builtin returns an error status, a non-interactive shell exits. |
| |
| </li><li> Assignment statements preceding the command stay in effect in the shell |
| environment after the command completes. |
| </li></ol> |
| |
| <p>When Bash is not executing in <small class="sc">POSIX</small> mode, these builtins behave no |
| differently than the rest of the Bash builtin commands. |
| The Bash <small class="sc">POSIX</small> mode is described in <a class="ref" href="#Bash-POSIX-Mode">Bash POSIX Mode</a>. |
| </p> |
| <p>These are the <small class="sc">POSIX</small> special builtins: |
| </p><div class="example"> |
| <pre class="example-preformatted">break : . continue eval exec exit export readonly return set<!-- /@w --> |
| shift trap unset<!-- /@w --> |
| </pre></div> |
| |
| <hr> |
| </div> |
| </div> |
| <div class="chapter-level-extent" id="Shell-Variables"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Bash-Features" accesskey="n" rel="next">Bash Features</a>, Previous: <a href="#Shell-Builtin-Commands" accesskey="p" rel="prev">Shell Builtin Commands</a>, Up: <a href="#Top" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h2 class="chapter" id="Shell-Variables-1"><span>5 Shell Variables<a class="copiable-link" href="#Shell-Variables-1"> ¶</a></span></h2> |
| |
| |
| <p>This chapter describes the shell variables that Bash uses. |
| Bash automatically assigns default values to a number of variables. |
| </p> |
| <ul class="mini-toc"> |
| <li><a href="#Bourne-Shell-Variables" accesskey="1">Bourne Shell Variables</a></li> |
| <li><a href="#Bash-Variables" accesskey="2">Bash Variables</a></li> |
| </ul> |
| <hr> |
| <div class="section-level-extent" id="Bourne-Shell-Variables"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Bash-Variables" accesskey="n" rel="next">Bash Variables</a>, Up: <a href="#Shell-Variables" accesskey="u" rel="up">Shell Variables</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Bourne-Shell-Variables-1"><span>5.1 Bourne Shell Variables<a class="copiable-link" href="#Bourne-Shell-Variables-1"> ¶</a></span></h3> |
| |
| <p>Bash uses certain shell variables in the same way as the Bourne shell. |
| In some cases, Bash assigns a default value to the variable. |
| </p> |
| <dl class="vtable"> |
| <dt><a id="index-CDPATH"></a><span><code class="code">CDPATH</code><a class="copiable-link" href="#index-CDPATH"> ¶</a></span></dt> |
| <dd><p>A colon-separated list of directories used as a search path for |
| the <code class="code">cd</code> builtin command. |
| </p> |
| </dd> |
| <dt><a id="index-HOME"></a><span><code class="code">HOME</code><a class="copiable-link" href="#index-HOME"> ¶</a></span></dt> |
| <dd><p>The current user’s home directory; the default for the <code class="code">cd</code> builtin |
| command. |
| The value of this variable is also used by tilde expansion |
| (see <a class="pxref" href="#Tilde-Expansion">Tilde Expansion</a>). |
| </p> |
| </dd> |
| <dt><a id="index-IFS"></a><span><code class="code">IFS</code><a class="copiable-link" href="#index-IFS"> ¶</a></span></dt> |
| <dd><p>A list of characters that separate fields; used when the shell splits |
| words as part of expansion. |
| </p> |
| </dd> |
| <dt><a id="index-MAIL"></a><span><code class="code">MAIL</code><a class="copiable-link" href="#index-MAIL"> ¶</a></span></dt> |
| <dd><p>If this parameter is set to a filename or directory name |
| and the <code class="env">MAILPATH</code> variable |
| is not set, Bash informs the user of the arrival of mail in |
| the specified file or Maildir-format directory. |
| </p> |
| </dd> |
| <dt><a id="index-MAILPATH"></a><span><code class="code">MAILPATH</code><a class="copiable-link" href="#index-MAILPATH"> ¶</a></span></dt> |
| <dd><p>A colon-separated list of filenames which the shell periodically checks |
| for new mail. |
| Each list entry can specify the message that is printed when new mail |
| arrives in the mail file by separating the filename from the message with |
| a ‘<samp class="samp">?</samp>’. |
| When used in the text of the message, <code class="code">$_</code> expands to the name of |
| the current mail file. |
| </p> |
| </dd> |
| <dt><a id="index-OPTARG"></a><span><code class="code">OPTARG</code><a class="copiable-link" href="#index-OPTARG"> ¶</a></span></dt> |
| <dd><p>The value of the last option argument processed by the <code class="code">getopts</code> builtin. |
| </p> |
| </dd> |
| <dt><a id="index-OPTIND"></a><span><code class="code">OPTIND</code><a class="copiable-link" href="#index-OPTIND"> ¶</a></span></dt> |
| <dd><p>The index of the last option argument processed by the <code class="code">getopts</code> builtin. |
| </p> |
| </dd> |
| <dt><a id="index-PATH"></a><span><code class="code">PATH</code><a class="copiable-link" href="#index-PATH"> ¶</a></span></dt> |
| <dd><p>A colon-separated list of directories in which the shell looks for |
| commands. |
| A zero-length (null) directory name in the value of <code class="code">PATH</code> indicates the |
| current directory. |
| A null directory name may appear as two adjacent colons, or as an initial |
| or trailing colon. |
| </p> |
| </dd> |
| <dt><a id="index-PS1"></a><span><code class="code">PS1</code><a class="copiable-link" href="#index-PS1"> ¶</a></span></dt> |
| <dd><p>The primary prompt string. The default value is ‘<samp class="samp">\s-\v\$ </samp>’. |
| See <a class="xref" href="#Controlling-the-Prompt">Controlling the Prompt</a>, for the complete list of escape |
| sequences that are expanded before <code class="env">PS1</code> is displayed. |
| </p> |
| </dd> |
| <dt><a id="index-PS2"></a><span><code class="code">PS2</code><a class="copiable-link" href="#index-PS2"> ¶</a></span></dt> |
| <dd><p>The secondary prompt string. The default value is ‘<samp class="samp">> </samp>’. |
| <code class="env">PS2</code> is expanded in the same way as <code class="env">PS1</code> before being |
| displayed. |
| </p> |
| </dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Bash-Variables"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Bourne-Shell-Variables" accesskey="p" rel="prev">Bourne Shell Variables</a>, Up: <a href="#Shell-Variables" accesskey="u" rel="up">Shell Variables</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Bash-Variables-1"><span>5.2 Bash Variables<a class="copiable-link" href="#Bash-Variables-1"> ¶</a></span></h3> |
| |
| <p>These variables are set or used by Bash, but other shells |
| do not normally treat them specially. |
| </p> |
| <p>A few variables used by Bash are described in different chapters: |
| variables for controlling the job control facilities |
| (see <a class="pxref" href="#Job-Control-Variables">Job Control Variables</a>). |
| </p> |
| <dl class="vtable"> |
| <dt><a id="index-_005f"></a><span><code class="code">_</code><a class="copiable-link" href="#index-_005f"> ¶</a></span></dt> |
| <dd><a class="index-entry-id" id="index-_0024_005f"></a> |
| <p>($_, an underscore.) |
| At shell startup, set to the pathname used to invoke the |
| shell or shell script being executed as passed in the environment |
| or argument list. |
| Subsequently, expands to the last argument to the previous simple |
| command executed in the foreground, after expansion. |
| Also set to the full pathname used to invoke each command executed |
| and placed in the environment exported to that command. |
| When checking mail, this parameter holds the name of the mail file. |
| </p> |
| </dd> |
| <dt><a id="index-BASH"></a><span><code class="code">BASH</code><a class="copiable-link" href="#index-BASH"> ¶</a></span></dt> |
| <dd><p>The full pathname used to execute the current instance of Bash. |
| </p> |
| </dd> |
| <dt><a id="index-BASHOPTS"></a><span><code class="code">BASHOPTS</code><a class="copiable-link" href="#index-BASHOPTS"> ¶</a></span></dt> |
| <dd><p>A colon-separated list of enabled shell options. Each word in |
| the list is a valid argument for the <samp class="option">-s</samp> option to the |
| <code class="code">shopt</code> builtin command (see <a class="pxref" href="#The-Shopt-Builtin">The Shopt Builtin</a>). |
| The options appearing in <code class="env">BASHOPTS</code> are those reported |
| as ‘<samp class="samp">on</samp>’ by ‘<samp class="samp">shopt</samp>’. |
| If this variable is in the environment when Bash |
| starts up, each shell option in the list will be enabled before |
| reading any startup files. This variable is readonly. |
| </p> |
| </dd> |
| <dt><a id="index-BASHPID"></a><span><code class="code">BASHPID</code><a class="copiable-link" href="#index-BASHPID"> ¶</a></span></dt> |
| <dd><p>Expands to the process ID of the current Bash process. |
| This differs from <code class="code">$$</code> under certain circumstances, such as subshells |
| that do not require Bash to be re-initialized. |
| Assignments to <code class="env">BASHPID</code> have no effect. |
| If <code class="env">BASHPID</code> |
| is unset, it loses its special properties, even if it is |
| subsequently reset. |
| </p> |
| </dd> |
| <dt><a id="index-BASH_005fALIASES"></a><span><code class="code">BASH_ALIASES</code><a class="copiable-link" href="#index-BASH_005fALIASES"> ¶</a></span></dt> |
| <dd><p>An associative array variable whose members correspond to the internal |
| list of aliases as maintained by the <code class="code">alias</code> builtin. |
| (see <a class="pxref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>). |
| Elements added to this array appear in the alias list; however, |
| unsetting array elements currently does not cause aliases to be removed |
| from the alias list. |
| If <code class="env">BASH_ALIASES</code> |
| is unset, it loses its special properties, even if it is |
| subsequently reset. |
| </p> |
| </dd> |
| <dt><a id="index-BASH_005fARGC"></a><span><code class="code">BASH_ARGC</code><a class="copiable-link" href="#index-BASH_005fARGC"> ¶</a></span></dt> |
| <dd><p>An array variable whose values are the number of parameters in each |
| frame of the current bash execution call stack. The number of |
| parameters to the current subroutine (shell function or script executed |
| with <code class="code">.</code> or <code class="code">source</code>) is at the top of the stack. When a |
| subroutine is executed, the number of parameters passed is pushed onto |
| <code class="code">BASH_ARGC</code>. |
| The shell sets <code class="code">BASH_ARGC</code> only when in extended debugging mode |
| (see <a class="ref" href="#The-Shopt-Builtin">The Shopt Builtin</a> |
| for a description of the <code class="code">extdebug</code> option to the <code class="code">shopt</code> |
| builtin). |
| Setting <code class="code">extdebug</code> after the shell has started to execute a script, |
| or referencing this variable when <code class="code">extdebug</code> is not set, |
| may result in inconsistent values. |
| </p> |
| </dd> |
| <dt><a id="index-BASH_005fARGV"></a><span><code class="code">BASH_ARGV</code><a class="copiable-link" href="#index-BASH_005fARGV"> ¶</a></span></dt> |
| <dd><p>An array variable containing all of the parameters in the current bash |
| execution call stack. The final parameter of the last subroutine call |
| is at the top of the stack; the first parameter of the initial call is |
| at the bottom. When a subroutine is executed, the parameters supplied |
| are pushed onto <code class="code">BASH_ARGV</code>. |
| The shell sets <code class="code">BASH_ARGV</code> only when in extended debugging mode |
| (see <a class="ref" href="#The-Shopt-Builtin">The Shopt Builtin</a> |
| for a description of the <code class="code">extdebug</code> option to the <code class="code">shopt</code> |
| builtin). |
| Setting <code class="code">extdebug</code> after the shell has started to execute a script, |
| or referencing this variable when <code class="code">extdebug</code> is not set, |
| may result in inconsistent values. |
| </p> |
| </dd> |
| <dt><a id="index-BASH_005fARGV0"></a><span><code class="code">BASH_ARGV0</code><a class="copiable-link" href="#index-BASH_005fARGV0"> ¶</a></span></dt> |
| <dd><p>When referenced, this variable expands to the name of the shell or shell |
| script (identical to <code class="code">$0</code>; See <a class="xref" href="#Special-Parameters">Special Parameters</a>, |
| for the description of special parameter 0). |
| Assignment to <code class="code">BASH_ARGV0</code> |
| causes the value assigned to also be assigned to <code class="code">$0</code>. |
| If <code class="env">BASH_ARGV0</code> |
| is unset, it loses its special properties, even if it is |
| subsequently reset. |
| </p> |
| </dd> |
| <dt><a id="index-BASH_005fCMDS"></a><span><code class="code">BASH_CMDS</code><a class="copiable-link" href="#index-BASH_005fCMDS"> ¶</a></span></dt> |
| <dd><p>An associative array variable whose members correspond to the internal |
| hash table of commands as maintained by the <code class="code">hash</code> builtin |
| (see <a class="pxref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>). |
| Elements added to this array appear in the hash table; however, |
| unsetting array elements currently does not cause command names to be removed |
| from the hash table. |
| If <code class="env">BASH_CMDS</code> |
| is unset, it loses its special properties, even if it is |
| subsequently reset. |
| </p> |
| </dd> |
| <dt><a id="index-BASH_005fCOMMAND"></a><span><code class="code">BASH_COMMAND</code><a class="copiable-link" href="#index-BASH_005fCOMMAND"> ¶</a></span></dt> |
| <dd><p>The command currently being executed or about to be executed, unless the |
| shell is executing a command as the result of a trap, |
| in which case it is the command executing at the time of the trap. |
| If <code class="env">BASH_COMMAND</code> |
| is unset, it loses its special properties, even if it is |
| subsequently reset. |
| </p> |
| </dd> |
| <dt><a id="index-BASH_005fCOMPAT"></a><span><code class="code">BASH_COMPAT</code><a class="copiable-link" href="#index-BASH_005fCOMPAT"> ¶</a></span></dt> |
| <dd><p>The value is used to set the shell’s compatibility level. |
| See <a class="xref" href="#Shell-Compatibility-Mode">Shell Compatibility Mode</a>, for a description of the various |
| compatibility levels and their effects. |
| The value may be a decimal number (e.g., 4.2) or an integer (e.g., 42) |
| corresponding to the desired compatibility level. |
| If <code class="env">BASH_COMPAT</code> is unset or set to the empty string, the compatibility |
| level is set to the default for the current version. |
| If <code class="env">BASH_COMPAT</code> is set to a value that is not one of the valid |
| compatibility levels, the shell prints an error message and sets the |
| compatibility level to the default for the current version. |
| The valid values correspond to the compatibility levels |
| described below (see <a class="pxref" href="#Shell-Compatibility-Mode">Shell Compatibility Mode</a>). |
| For example, 4.2 and 42 are valid values that correspond |
| to the <code class="code">compat42</code> <code class="code">shopt</code> option |
| and set the compatibility level to 42. |
| The current version is also a valid value. |
| </p> |
| </dd> |
| <dt><a id="index-BASH_005fENV"></a><span><code class="code">BASH_ENV</code><a class="copiable-link" href="#index-BASH_005fENV"> ¶</a></span></dt> |
| <dd><p>If this variable is set when Bash is invoked to execute a shell |
| script, its value is expanded and used as the name of a startup file |
| to read before executing the script. See <a class="xref" href="#Bash-Startup-Files">Bash Startup Files</a>. |
| </p> |
| </dd> |
| <dt><a id="index-BASH_005fEXECUTION_005fSTRING"></a><span><code class="code">BASH_EXECUTION_STRING</code><a class="copiable-link" href="#index-BASH_005fEXECUTION_005fSTRING"> ¶</a></span></dt> |
| <dd><p>The command argument to the <samp class="option">-c</samp> invocation option. |
| </p> |
| </dd> |
| <dt><a id="index-BASH_005fLINENO"></a><span><code class="code">BASH_LINENO</code><a class="copiable-link" href="#index-BASH_005fLINENO"> ¶</a></span></dt> |
| <dd><p>An array variable whose members are the line numbers in source files |
| where each corresponding member of <code class="env">FUNCNAME</code> was invoked. |
| <code class="code">${BASH_LINENO[$i]}</code> is the line number in the source file |
| (<code class="code">${BASH_SOURCE[$i+1]}</code>) where |
| <code class="code">${FUNCNAME[$i]}</code> was called (or <code class="code">${BASH_LINENO[$i-1]}</code> if |
| referenced within another shell function). |
| Use <code class="code">LINENO</code> to obtain the current line number. |
| </p> |
| </dd> |
| <dt><a id="index-BASH_005fLOADABLES_005fPATH"></a><span><code class="code">BASH_LOADABLES_PATH</code><a class="copiable-link" href="#index-BASH_005fLOADABLES_005fPATH"> ¶</a></span></dt> |
| <dd><p>A colon-separated list of directories in which the shell looks for |
| dynamically loadable builtins specified by the |
| <code class="code">enable</code> command. |
| </p> |
| </dd> |
| <dt><a id="index-BASH_005fREMATCH"></a><span><code class="code">BASH_REMATCH</code><a class="copiable-link" href="#index-BASH_005fREMATCH"> ¶</a></span></dt> |
| <dd><p>An array variable whose members are assigned by the ‘<samp class="samp">=~</samp>’ binary |
| operator to the <code class="code">[[</code> conditional command |
| (see <a class="pxref" href="#Conditional-Constructs">Conditional Constructs</a>). |
| The element with index 0 is the portion of the string |
| matching the entire regular expression. |
| The element with index <var class="var">n</var> is the portion of the |
| string matching the <var class="var">n</var>th parenthesized subexpression. |
| </p> |
| </dd> |
| <dt><a id="index-BASH_005fSOURCE"></a><span><code class="code">BASH_SOURCE</code><a class="copiable-link" href="#index-BASH_005fSOURCE"> ¶</a></span></dt> |
| <dd><p>An array variable whose members are the source filenames where the |
| corresponding shell function names in the <code class="code">FUNCNAME</code> array |
| variable are defined. |
| The shell function <code class="code">${FUNCNAME[$i]}</code> is defined in the file |
| <code class="code">${BASH_SOURCE[$i]}</code> and called from <code class="code">${BASH_SOURCE[$i+1]}</code> |
| </p> |
| </dd> |
| <dt><a id="index-BASH_005fSUBSHELL"></a><span><code class="code">BASH_SUBSHELL</code><a class="copiable-link" href="#index-BASH_005fSUBSHELL"> ¶</a></span></dt> |
| <dd><p>Incremented by one within each subshell or subshell environment when |
| the shell begins executing in that environment. |
| The initial value is 0. |
| If <code class="env">BASH_SUBSHELL</code> |
| is unset, it loses its special properties, even if it is |
| subsequently reset. |
| </p> |
| </dd> |
| <dt><a id="index-BASH_005fVERSINFO"></a><span><code class="code">BASH_VERSINFO</code><a class="copiable-link" href="#index-BASH_005fVERSINFO"> ¶</a></span></dt> |
| <dd><p>A readonly array variable (see <a class="pxref" href="#Arrays">Arrays</a>) |
| whose members hold version information for this instance of Bash. |
| The values assigned to the array members are as follows: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">BASH_VERSINFO[0]</code></dt> |
| <dd><p>The major version number (the <em class="dfn">release</em>). |
| </p> |
| </dd> |
| <dt><code class="code">BASH_VERSINFO[1]</code></dt> |
| <dd><p>The minor version number (the <em class="dfn">version</em>). |
| </p> |
| </dd> |
| <dt><code class="code">BASH_VERSINFO[2]</code></dt> |
| <dd><p>The patch level. |
| </p> |
| </dd> |
| <dt><code class="code">BASH_VERSINFO[3]</code></dt> |
| <dd><p>The build version. |
| </p> |
| </dd> |
| <dt><code class="code">BASH_VERSINFO[4]</code></dt> |
| <dd><p>The release status (e.g., <code class="code">beta1</code>). |
| </p> |
| </dd> |
| <dt><code class="code">BASH_VERSINFO[5]</code></dt> |
| <dd><p>The value of <code class="env">MACHTYPE</code>. |
| </p></dd> |
| </dl> |
| |
| </dd> |
| <dt><a id="index-BASH_005fVERSION"></a><span><code class="code">BASH_VERSION</code><a class="copiable-link" href="#index-BASH_005fVERSION"> ¶</a></span></dt> |
| <dd><p>The version number of the current instance of Bash. |
| </p> |
| </dd> |
| <dt><a id="index-BASH_005fXTRACEFD"></a><span><code class="code">BASH_XTRACEFD</code><a class="copiable-link" href="#index-BASH_005fXTRACEFD"> ¶</a></span></dt> |
| <dd><p>If set to an integer corresponding to a valid file descriptor, Bash |
| will write the trace output generated when ‘<samp class="samp">set -x</samp>’ |
| is enabled to that file descriptor. |
| This allows tracing output to be separated from diagnostic and error |
| messages. |
| The file descriptor is closed when <code class="code">BASH_XTRACEFD</code> is unset or assigned |
| a new value. |
| Unsetting <code class="code">BASH_XTRACEFD</code> or assigning it the empty string causes the |
| trace output to be sent to the standard error. |
| Note that setting <code class="code">BASH_XTRACEFD</code> to 2 (the standard error file |
| descriptor) and then unsetting it will result in the standard error |
| being closed. |
| </p> |
| </dd> |
| <dt><a id="index-CHILD_005fMAX"></a><span><code class="code">CHILD_MAX</code><a class="copiable-link" href="#index-CHILD_005fMAX"> ¶</a></span></dt> |
| <dd><p>Set the number of exited child status values for the shell to remember. |
| Bash will not allow this value to be decreased below a <small class="sc">POSIX</small>-mandated |
| minimum, and there is a maximum value (currently 8192) that this may |
| not exceed. |
| The minimum value is system-dependent. |
| </p> |
| </dd> |
| <dt><a id="index-COLUMNS"></a><span><code class="code">COLUMNS</code><a class="copiable-link" href="#index-COLUMNS"> ¶</a></span></dt> |
| <dd><p>Used by the <code class="code">select</code> command to determine the terminal width |
| when printing selection lists. |
| Automatically set if the <code class="code">checkwinsize</code> option is enabled |
| (see <a class="pxref" href="#The-Shopt-Builtin">The Shopt Builtin</a>), or in an interactive shell upon receipt of a |
| <code class="code">SIGWINCH</code>. |
| </p> |
| </dd> |
| <dt><a id="index-COMP_005fCWORD"></a><span><code class="code">COMP_CWORD</code><a class="copiable-link" href="#index-COMP_005fCWORD"> ¶</a></span></dt> |
| <dd><p>An index into <code class="env">${COMP_WORDS}</code> of the word containing the current |
| cursor position. |
| This variable is available only in shell functions invoked by the |
| programmable completion facilities (see <a class="pxref" href="#Programmable-Completion">Programmable Completion</a>). |
| </p> |
| </dd> |
| <dt><a id="index-COMP_005fLINE"></a><span><code class="code">COMP_LINE</code><a class="copiable-link" href="#index-COMP_005fLINE"> ¶</a></span></dt> |
| <dd><p>The current command line. |
| This variable is available only in shell functions and external |
| commands invoked by the |
| programmable completion facilities (see <a class="pxref" href="#Programmable-Completion">Programmable Completion</a>). |
| </p> |
| </dd> |
| <dt><a id="index-COMP_005fPOINT"></a><span><code class="code">COMP_POINT</code><a class="copiable-link" href="#index-COMP_005fPOINT"> ¶</a></span></dt> |
| <dd><p>The index of the current cursor position relative to the beginning of |
| the current command. |
| If the current cursor position is at the end of the current command, |
| the value of this variable is equal to <code class="code">${#COMP_LINE}</code>. |
| This variable is available only in shell functions and external |
| commands invoked by the |
| programmable completion facilities (see <a class="pxref" href="#Programmable-Completion">Programmable Completion</a>). |
| </p> |
| </dd> |
| <dt><a id="index-COMP_005fTYPE"></a><span><code class="code">COMP_TYPE</code><a class="copiable-link" href="#index-COMP_005fTYPE"> ¶</a></span></dt> |
| <dd><p>Set to an integer value corresponding to the type of completion attempted |
| that caused a completion function to be called: |
| <kbd class="key">TAB</kbd>, for normal completion, |
| ‘<samp class="samp">?</samp>’, for listing completions after successive tabs, |
| ‘<samp class="samp">!</samp>’, for listing alternatives on partial word completion, |
| ‘<samp class="samp">@</samp>’, to list completions if the word is not unmodified, |
| or |
| ‘<samp class="samp">%</samp>’, for menu completion. |
| This variable is available only in shell functions and external |
| commands invoked by the |
| programmable completion facilities (see <a class="pxref" href="#Programmable-Completion">Programmable Completion</a>). |
| </p> |
| </dd> |
| <dt><a id="index-COMP_005fKEY"></a><span><code class="code">COMP_KEY</code><a class="copiable-link" href="#index-COMP_005fKEY"> ¶</a></span></dt> |
| <dd><p>The key (or final key of a key sequence) used to invoke the current |
| completion function. |
| </p> |
| </dd> |
| <dt><a id="index-COMP_005fWORDBREAKS"></a><span><code class="code">COMP_WORDBREAKS</code><a class="copiable-link" href="#index-COMP_005fWORDBREAKS"> ¶</a></span></dt> |
| <dd><p>The set of characters that the Readline library treats as word |
| separators when performing word completion. |
| If <code class="env">COMP_WORDBREAKS</code> |
| is unset, it loses its special properties, |
| even if it is subsequently reset. |
| </p> |
| </dd> |
| <dt><a id="index-COMP_005fWORDS"></a><span><code class="code">COMP_WORDS</code><a class="copiable-link" href="#index-COMP_005fWORDS"> ¶</a></span></dt> |
| <dd><p>An array variable consisting of the individual |
| words in the current command line. |
| The line is split into words as Readline would split it, using |
| <code class="code">COMP_WORDBREAKS</code> as described above. |
| This variable is available only in shell functions invoked by the |
| programmable completion facilities (see <a class="pxref" href="#Programmable-Completion">Programmable Completion</a>). |
| </p> |
| </dd> |
| <dt><a id="index-COMPREPLY"></a><span><code class="code">COMPREPLY</code><a class="copiable-link" href="#index-COMPREPLY"> ¶</a></span></dt> |
| <dd><p>An array variable from which Bash reads the possible completions |
| generated by a shell function invoked by the programmable completion |
| facility (see <a class="pxref" href="#Programmable-Completion">Programmable Completion</a>). |
| Each array element contains one possible completion. |
| </p> |
| </dd> |
| <dt><a id="index-COPROC"></a><span><code class="code">COPROC</code><a class="copiable-link" href="#index-COPROC"> ¶</a></span></dt> |
| <dd><p>An array variable created to hold the file descriptors |
| for output from and input to an unnamed coprocess (see <a class="pxref" href="#Coprocesses">Coprocesses</a>). |
| </p> |
| </dd> |
| <dt><a id="index-DIRSTACK"></a><span><code class="code">DIRSTACK</code><a class="copiable-link" href="#index-DIRSTACK"> ¶</a></span></dt> |
| <dd><p>An array variable containing the current contents of the directory stack. |
| Directories appear in the stack in the order they are displayed by the |
| <code class="code">dirs</code> builtin. |
| Assigning to members of this array variable may be used to modify |
| directories already in the stack, but the <code class="code">pushd</code> and <code class="code">popd</code> |
| builtins must be used to add and remove directories. |
| Assignment to this variable will not change the current directory. |
| If <code class="env">DIRSTACK</code> |
| is unset, it loses its special properties, even if |
| it is subsequently reset. |
| </p> |
| </dd> |
| <dt><a id="index-EMACS"></a><span><code class="code">EMACS</code><a class="copiable-link" href="#index-EMACS"> ¶</a></span></dt> |
| <dd><p>If Bash finds this variable in the environment when the shell |
| starts with value ‘<samp class="samp">t</samp>’, it assumes that the shell is running in an |
| Emacs shell buffer and disables line editing. |
| </p> |
| </dd> |
| <dt><a id="index-ENV"></a><span><code class="code">ENV</code><a class="copiable-link" href="#index-ENV"> ¶</a></span></dt> |
| <dd><p>Expanded and executed similarly to <code class="code">BASH_ENV</code> |
| (see <a class="pxref" href="#Bash-Startup-Files">Bash Startup Files</a>) |
| when an interactive shell is invoked in |
| <small class="sc">POSIX</small> Mode (see <a class="pxref" href="#Bash-POSIX-Mode">Bash POSIX Mode</a>). |
| </p> |
| </dd> |
| <dt><a id="index-EPOCHREALTIME"></a><span><code class="code">EPOCHREALTIME</code><a class="copiable-link" href="#index-EPOCHREALTIME"> ¶</a></span></dt> |
| <dd><p>Each time this parameter is referenced, it expands to the number of seconds |
| since the Unix Epoch as a floating point value with micro-second granularity |
| (see the documentation for the C library function <code class="code">time</code> for the |
| definition of Epoch). |
| Assignments to <code class="env">EPOCHREALTIME</code> are ignored. |
| If <code class="env">EPOCHREALTIME</code> |
| is unset, it loses its special properties, even if |
| it is subsequently reset. |
| </p> |
| </dd> |
| <dt><a id="index-EPOCHSECONDS"></a><span><code class="code">EPOCHSECONDS</code><a class="copiable-link" href="#index-EPOCHSECONDS"> ¶</a></span></dt> |
| <dd><p>Each time this parameter is referenced, it expands to the number of seconds |
| since the Unix Epoch (see the documentation for the C library function |
| <code class="code">time</code> for the definition of Epoch). |
| Assignments to <code class="env">EPOCHSECONDS</code> are ignored. |
| If <code class="env">EPOCHSECONDS</code> |
| is unset, it loses its special properties, even if |
| it is subsequently reset. |
| </p> |
| </dd> |
| <dt><a id="index-EUID"></a><span><code class="code">EUID</code><a class="copiable-link" href="#index-EUID"> ¶</a></span></dt> |
| <dd><p>The numeric effective user id of the current user. This variable |
| is readonly. |
| </p> |
| </dd> |
| <dt><a id="index-EXECIGNORE"></a><span><code class="code">EXECIGNORE</code><a class="copiable-link" href="#index-EXECIGNORE"> ¶</a></span></dt> |
| <dd><p>A colon-separated list of shell patterns (see <a class="pxref" href="#Pattern-Matching">Pattern Matching</a>) |
| defining the list of filenames to be ignored by command search using |
| <code class="code">PATH</code>. |
| Files whose full pathnames match one of these patterns are not considered |
| executable files for the purposes of completion and command execution |
| via <code class="code">PATH</code> lookup. |
| This does not affect the behavior of the <code class="code">[</code>, <code class="code">test</code>, and <code class="code">[[</code> |
| commands. |
| Full pathnames in the command hash table are not subject to <code class="code">EXECIGNORE</code>. |
| Use this variable to ignore shared library files that have the executable |
| bit set, but are not executable files. |
| The pattern matching honors the setting of the <code class="code">extglob</code> shell |
| option. |
| </p> |
| </dd> |
| <dt><a id="index-FCEDIT"></a><span><code class="code">FCEDIT</code><a class="copiable-link" href="#index-FCEDIT"> ¶</a></span></dt> |
| <dd><p>The editor used as a default by the <samp class="option">-e</samp> option to the <code class="code">fc</code> |
| builtin command. |
| </p> |
| </dd> |
| <dt><a id="index-FIGNORE"></a><span><code class="code">FIGNORE</code><a class="copiable-link" href="#index-FIGNORE"> ¶</a></span></dt> |
| <dd><p>A colon-separated list of suffixes to ignore when performing |
| filename completion. |
| A filename whose suffix matches one of the entries in |
| <code class="env">FIGNORE</code> |
| is excluded from the list of matched filenames. A sample |
| value is ‘<samp class="samp">.o:~</samp>’ |
| </p> |
| </dd> |
| <dt><a id="index-FUNCNAME"></a><span><code class="code">FUNCNAME</code><a class="copiable-link" href="#index-FUNCNAME"> ¶</a></span></dt> |
| <dd><p>An array variable containing the names of all shell functions |
| currently in the execution call stack. |
| The element with index 0 is the name of any currently-executing |
| shell function. |
| The bottom-most element (the one with the highest index) |
| is <code class="code">"main"</code>. |
| This variable exists only when a shell function is executing. |
| Assignments to <code class="env">FUNCNAME</code> have no effect. |
| If <code class="env">FUNCNAME</code> |
| is unset, it loses its special properties, even if |
| it is subsequently reset. |
| </p> |
| <p>This variable can be used with <code class="code">BASH_LINENO</code> and <code class="code">BASH_SOURCE</code>. |
| Each element of <code class="code">FUNCNAME</code> has corresponding elements in |
| <code class="code">BASH_LINENO</code> and <code class="code">BASH_SOURCE</code> to describe the call stack. |
| For instance, <code class="code">${FUNCNAME[$i]}</code> was called from the file |
| <code class="code">${BASH_SOURCE[$i+1]}</code> at line number <code class="code">${BASH_LINENO[$i]}</code>. |
| The <code class="code">caller</code> builtin displays the current call stack using this |
| information. |
| </p> |
| </dd> |
| <dt><a id="index-FUNCNEST"></a><span><code class="code">FUNCNEST</code><a class="copiable-link" href="#index-FUNCNEST"> ¶</a></span></dt> |
| <dd><p>If set to a numeric value greater than 0, defines a maximum function |
| nesting level. Function invocations that exceed this nesting level |
| will cause the current command to abort. |
| </p> |
| </dd> |
| <dt><a id="index-GLOBIGNORE"></a><span><code class="code">GLOBIGNORE</code><a class="copiable-link" href="#index-GLOBIGNORE"> ¶</a></span></dt> |
| <dd><p>A colon-separated list of patterns defining the set of file names to |
| be ignored by filename expansion. |
| If a file name matched by a filename expansion pattern also matches one |
| of the patterns in <code class="env">GLOBIGNORE</code>, it is removed from the list |
| of matches. |
| The pattern matching honors the setting of the <code class="code">extglob</code> shell |
| option. |
| </p> |
| </dd> |
| <dt><a id="index-GROUPS"></a><span><code class="code">GROUPS</code><a class="copiable-link" href="#index-GROUPS"> ¶</a></span></dt> |
| <dd><p>An array variable containing the list of groups of which the current |
| user is a member. |
| Assignments to <code class="env">GROUPS</code> have no effect. |
| If <code class="env">GROUPS</code> |
| is unset, it loses its special properties, even if it is |
| subsequently reset. |
| </p> |
| </dd> |
| <dt><a id="index-histchars"></a><span><code class="code">histchars</code><a class="copiable-link" href="#index-histchars"> ¶</a></span></dt> |
| <dd><p>Up to three characters which control history expansion, quick |
| substitution, and tokenization (see <a class="pxref" href="#History-Interaction">History Expansion</a>). |
| The first character is the |
| <em class="dfn">history expansion</em> character, that is, the character which signifies the |
| start of a history expansion, normally ‘<samp class="samp">!</samp>’. The second character is the |
| character which signifies ‘quick substitution’ when seen as the first |
| character on a line, normally ‘<samp class="samp">^</samp>’. The optional third character is the |
| character which indicates that the remainder of the line is a comment when |
| found as the first character of a word, usually ‘<samp class="samp">#</samp>’. The history |
| comment character causes history substitution to be skipped for the |
| remaining words on the line. It does not necessarily cause the shell |
| parser to treat the rest of the line as a comment. |
| </p> |
| </dd> |
| <dt><a id="index-HISTCMD"></a><span><code class="code">HISTCMD</code><a class="copiable-link" href="#index-HISTCMD"> ¶</a></span></dt> |
| <dd><p>The history number, or index in the history list, of the current |
| command. |
| Assignments to <code class="env">HISTCMD</code> are ignored. |
| If <code class="env">HISTCMD</code> |
| is unset, it loses its special properties, |
| even if it is subsequently reset. |
| </p> |
| </dd> |
| <dt><a id="index-HISTCONTROL"></a><span><code class="code">HISTCONTROL</code><a class="copiable-link" href="#index-HISTCONTROL"> ¶</a></span></dt> |
| <dd><p>A colon-separated list of values controlling how commands are saved on |
| the history list. |
| If the list of values includes ‘<samp class="samp">ignorespace</samp>’, lines which begin |
| with a space character are not saved in the history list. |
| A value of ‘<samp class="samp">ignoredups</samp>’ causes lines which match the previous |
| history entry to not be saved. |
| A value of ‘<samp class="samp">ignoreboth</samp>’ is shorthand for |
| ‘<samp class="samp">ignorespace</samp>’ and ‘<samp class="samp">ignoredups</samp>’. |
| A value of ‘<samp class="samp">erasedups</samp>’ causes all previous lines matching the |
| current line to be removed from the history list before that line |
| is saved. |
| Any value not in the above list is ignored. |
| If <code class="env">HISTCONTROL</code> is unset, or does not include a valid value, |
| all lines read by the shell parser are saved on the history list, |
| subject to the value of <code class="env">HISTIGNORE</code>. |
| The second and subsequent lines of a multi-line compound command are |
| not tested, and are added to the history regardless of the value of |
| <code class="env">HISTCONTROL</code>. |
| </p> |
| </dd> |
| <dt><a id="index-HISTFILE"></a><span><code class="code">HISTFILE</code><a class="copiable-link" href="#index-HISTFILE"> ¶</a></span></dt> |
| <dd><p>The name of the file to which the command history is saved. The |
| default value is <samp class="file">~/.bash_history</samp>. |
| </p> |
| </dd> |
| <dt><a id="index-HISTFILESIZE"></a><span><code class="code">HISTFILESIZE</code><a class="copiable-link" href="#index-HISTFILESIZE"> ¶</a></span></dt> |
| <dd><p>The maximum number of lines contained in the history file. |
| When this variable is assigned a value, the history file is truncated, |
| if necessary, to contain no more than that number of lines |
| by removing the oldest entries. |
| The history file is also truncated to this size after |
| writing it when a shell exits. |
| If the value is 0, the history file is truncated to zero size. |
| Non-numeric values and numeric values less than zero inhibit truncation. |
| The shell sets the default value to the value of <code class="env">HISTSIZE</code> |
| after reading any startup files. |
| </p> |
| </dd> |
| <dt><a id="index-HISTIGNORE"></a><span><code class="code">HISTIGNORE</code><a class="copiable-link" href="#index-HISTIGNORE"> ¶</a></span></dt> |
| <dd><p>A colon-separated list of patterns used to decide which command |
| lines should be saved on the history list. Each pattern is |
| anchored at the beginning of the line and must match the complete |
| line (no implicit ‘<samp class="samp">*</samp>’ is appended). Each pattern is tested |
| against the line after the checks specified by <code class="env">HISTCONTROL</code> |
| are applied. In addition to the normal shell pattern matching |
| characters, ‘<samp class="samp">&</samp>’ matches the previous history line. ‘<samp class="samp">&</samp>’ |
| may be escaped using a backslash; the backslash is removed |
| before attempting a match. |
| The second and subsequent lines of a multi-line compound command are |
| not tested, and are added to the history regardless of the value of |
| <code class="env">HISTIGNORE</code>. |
| The pattern matching honors the setting of the <code class="code">extglob</code> shell |
| option. |
| </p> |
| <p><code class="env">HISTIGNORE</code> subsumes the function of <code class="env">HISTCONTROL</code>. A |
| pattern of ‘<samp class="samp">&</samp>’ is identical to <code class="code">ignoredups</code>, and a |
| pattern of ‘<samp class="samp">[ ]*</samp>’ is identical to <code class="code">ignorespace</code>. |
| Combining these two patterns, separating them with a colon, |
| provides the functionality of <code class="code">ignoreboth</code>. |
| </p> |
| </dd> |
| <dt><a id="index-HISTSIZE"></a><span><code class="code">HISTSIZE</code><a class="copiable-link" href="#index-HISTSIZE"> ¶</a></span></dt> |
| <dd><p>The maximum number of commands to remember on the history list. |
| If the value is 0, commands are not saved in the history list. |
| Numeric values less than zero result in every command being saved |
| on the history list (there is no limit). |
| The shell sets the default value to 500 after reading any startup files. |
| </p> |
| </dd> |
| <dt><a id="index-HISTTIMEFORMAT"></a><span><code class="code">HISTTIMEFORMAT</code><a class="copiable-link" href="#index-HISTTIMEFORMAT"> ¶</a></span></dt> |
| <dd><p>If this variable is set and not null, its value is used as a format string |
| for <code class="code">strftime</code> to print the time stamp associated with each history |
| entry displayed by the <code class="code">history</code> builtin. |
| If this variable is set, time stamps are written to the history file so |
| they may be preserved across shell sessions. |
| This uses the history comment character to distinguish timestamps from |
| other history lines. |
| </p> |
| </dd> |
| <dt><a id="index-HOSTFILE"></a><span><code class="code">HOSTFILE</code><a class="copiable-link" href="#index-HOSTFILE"> ¶</a></span></dt> |
| <dd><p>Contains the name of a file in the same format as <samp class="file">/etc/hosts</samp> that |
| should be read when the shell needs to complete a hostname. |
| The list of possible hostname completions may be changed while the shell |
| is running; |
| the next time hostname completion is attempted after the |
| value is changed, Bash adds the contents of the new file to the |
| existing list. |
| If <code class="env">HOSTFILE</code> is set, but has no value, or does not name a readable file, |
| Bash attempts to read |
| <samp class="file">/etc/hosts</samp> to obtain the list of possible hostname completions. |
| When <code class="env">HOSTFILE</code> is unset, the hostname list is cleared. |
| </p> |
| </dd> |
| <dt><a id="index-HOSTNAME"></a><span><code class="code">HOSTNAME</code><a class="copiable-link" href="#index-HOSTNAME"> ¶</a></span></dt> |
| <dd><p>The name of the current host. |
| </p> |
| </dd> |
| <dt><a id="index-HOSTTYPE"></a><span><code class="code">HOSTTYPE</code><a class="copiable-link" href="#index-HOSTTYPE"> ¶</a></span></dt> |
| <dd><p>A string describing the machine Bash is running on. |
| </p> |
| </dd> |
| <dt><a id="index-IGNOREEOF"></a><span><code class="code">IGNOREEOF</code><a class="copiable-link" href="#index-IGNOREEOF"> ¶</a></span></dt> |
| <dd><p>Controls the action of the shell on receipt of an <code class="code">EOF</code> character |
| as the sole input. If set, the value denotes the number |
| of consecutive <code class="code">EOF</code> characters that can be read as the |
| first character on an input line |
| before the shell will exit. If the variable exists but does not |
| have a numeric value, or has no value, then the default is 10. |
| If the variable does not exist, then <code class="code">EOF</code> signifies the end of |
| input to the shell. This is only in effect for interactive shells. |
| </p> |
| </dd> |
| <dt><a id="index-INPUTRC"></a><span><code class="code">INPUTRC</code><a class="copiable-link" href="#index-INPUTRC"> ¶</a></span></dt> |
| <dd><p>The name of the Readline initialization file, overriding the default |
| of <samp class="file">~/.inputrc</samp>. |
| </p> |
| </dd> |
| <dt><a id="index-INSIDE_005fEMACS"></a><span><code class="code">INSIDE_EMACS</code><a class="copiable-link" href="#index-INSIDE_005fEMACS"> ¶</a></span></dt> |
| <dd><p>If Bash finds this variable in the environment when the shell |
| starts, it assumes that the shell is running in an Emacs shell buffer |
| and may disable line editing depending on the value of <code class="env">TERM</code>. |
| </p> |
| </dd> |
| <dt><a id="index-LANG-1"></a><span><code class="code">LANG</code><a class="copiable-link" href="#index-LANG-1"> ¶</a></span></dt> |
| <dd><p>Used to determine the locale category for any category not specifically |
| selected with a variable starting with <code class="code">LC_</code>. |
| </p> |
| </dd> |
| <dt><a id="index-LC_005fALL"></a><span><code class="code">LC_ALL</code><a class="copiable-link" href="#index-LC_005fALL"> ¶</a></span></dt> |
| <dd><p>This variable overrides the value of <code class="env">LANG</code> and any other |
| <code class="code">LC_</code> variable specifying a locale category. |
| </p> |
| </dd> |
| <dt><a id="index-LC_005fCOLLATE"></a><span><code class="code">LC_COLLATE</code><a class="copiable-link" href="#index-LC_005fCOLLATE"> ¶</a></span></dt> |
| <dd><p>This variable determines the collation order used when sorting the |
| results of filename expansion, and |
| determines the behavior of range expressions, equivalence classes, |
| and collating sequences within filename expansion and pattern matching |
| (see <a class="pxref" href="#Filename-Expansion">Filename Expansion</a>). |
| </p> |
| </dd> |
| <dt><a id="index-LC_005fCTYPE"></a><span><code class="code">LC_CTYPE</code><a class="copiable-link" href="#index-LC_005fCTYPE"> ¶</a></span></dt> |
| <dd><p>This variable determines the interpretation of characters and the |
| behavior of character classes within filename expansion and pattern |
| matching (see <a class="pxref" href="#Filename-Expansion">Filename Expansion</a>). |
| </p> |
| </dd> |
| <dt><a id="index-LC_005fMESSAGES-1"></a><span><code class="code">LC_MESSAGES</code><a class="copiable-link" href="#index-LC_005fMESSAGES-1"> ¶</a></span></dt> |
| <dd><p>This variable determines the locale used to translate double-quoted |
| strings preceded by a ‘<samp class="samp">$</samp>’ (see <a class="pxref" href="#Locale-Translation">Locale-Specific Translation</a>). |
| </p> |
| </dd> |
| <dt><a id="index-LC_005fNUMERIC"></a><span><code class="code">LC_NUMERIC</code><a class="copiable-link" href="#index-LC_005fNUMERIC"> ¶</a></span></dt> |
| <dd><p>This variable determines the locale category used for number formatting. |
| </p> |
| </dd> |
| <dt><a id="index-LC_005fTIME"></a><span><code class="code">LC_TIME</code><a class="copiable-link" href="#index-LC_005fTIME"> ¶</a></span></dt> |
| <dd><p>This variable determines the locale category used for data and time |
| formatting. |
| </p> |
| </dd> |
| <dt><a id="index-LINENO"></a><span><code class="code">LINENO</code><a class="copiable-link" href="#index-LINENO"> ¶</a></span></dt> |
| <dd><p>The line number in the script or shell function currently executing. |
| If <code class="env">LINENO</code> |
| is unset, it loses its special properties, even if it is |
| subsequently reset. |
| </p> |
| </dd> |
| <dt><a id="index-LINES"></a><span><code class="code">LINES</code><a class="copiable-link" href="#index-LINES"> ¶</a></span></dt> |
| <dd><p>Used by the <code class="code">select</code> command to determine the column length |
| for printing selection lists. |
| Automatically set if the <code class="code">checkwinsize</code> option is enabled |
| (see <a class="pxref" href="#The-Shopt-Builtin">The Shopt Builtin</a>), or in an interactive shell upon receipt of a |
| <code class="code">SIGWINCH</code>. |
| </p> |
| </dd> |
| <dt><a id="index-MACHTYPE"></a><span><code class="code">MACHTYPE</code><a class="copiable-link" href="#index-MACHTYPE"> ¶</a></span></dt> |
| <dd><p>A string that fully describes the system type on which Bash |
| is executing, in the standard <small class="sc">GNU</small> <var class="var">cpu-company-system</var> format. |
| </p> |
| </dd> |
| <dt><a id="index-MAILCHECK"></a><span><code class="code">MAILCHECK</code><a class="copiable-link" href="#index-MAILCHECK"> ¶</a></span></dt> |
| <dd><p>How often (in seconds) that the shell should check for mail in the |
| files specified in the <code class="env">MAILPATH</code> or <code class="env">MAIL</code> variables. |
| The default is 60 seconds. When it is time to check |
| for mail, the shell does so before displaying the primary prompt. |
| If this variable is unset, or set to a value that is not a number |
| greater than or equal to zero, the shell disables mail checking. |
| </p> |
| </dd> |
| <dt><a id="index-MAPFILE"></a><span><code class="code">MAPFILE</code><a class="copiable-link" href="#index-MAPFILE"> ¶</a></span></dt> |
| <dd><p>An array variable created to hold the text read by the |
| <code class="code">mapfile</code> builtin when no variable name is supplied. |
| </p> |
| </dd> |
| <dt><a id="index-OLDPWD"></a><span><code class="code">OLDPWD</code><a class="copiable-link" href="#index-OLDPWD"> ¶</a></span></dt> |
| <dd><p>The previous working directory as set by the <code class="code">cd</code> builtin. |
| </p> |
| </dd> |
| <dt><a id="index-OPTERR"></a><span><code class="code">OPTERR</code><a class="copiable-link" href="#index-OPTERR"> ¶</a></span></dt> |
| <dd><p>If set to the value 1, Bash displays error messages |
| generated by the <code class="code">getopts</code> builtin command. |
| </p> |
| </dd> |
| <dt><a id="index-OSTYPE"></a><span><code class="code">OSTYPE</code><a class="copiable-link" href="#index-OSTYPE"> ¶</a></span></dt> |
| <dd><p>A string describing the operating system Bash is running on. |
| </p> |
| </dd> |
| <dt><a id="index-PIPESTATUS"></a><span><code class="code">PIPESTATUS</code><a class="copiable-link" href="#index-PIPESTATUS"> ¶</a></span></dt> |
| <dd><p>An array variable (see <a class="pxref" href="#Arrays">Arrays</a>) |
| containing a list of exit status values from the processes |
| in the most-recently-executed foreground pipeline (which may |
| contain only a single command). |
| </p> |
| </dd> |
| <dt><a id="index-POSIXLY_005fCORRECT"></a><span><code class="code">POSIXLY_CORRECT</code><a class="copiable-link" href="#index-POSIXLY_005fCORRECT"> ¶</a></span></dt> |
| <dd><p>If this variable is in the environment when Bash starts, the shell |
| enters <small class="sc">POSIX</small> mode (see <a class="pxref" href="#Bash-POSIX-Mode">Bash POSIX Mode</a>) before reading the |
| startup files, as if the <samp class="option">--posix</samp> invocation option had been supplied. |
| If it is set while the shell is running, Bash enables <small class="sc">POSIX</small> mode, |
| as if the command |
| </p><div class="example"> |
| <pre class="example-preformatted"><code class="code">set -o posix</code> |
| </pre></div> |
| <p>had been executed. |
| When the shell enters <small class="sc">POSIX</small> mode, it sets this variable if it was |
| not already set. |
| </p> |
| </dd> |
| <dt><a id="index-PPID"></a><span><code class="code">PPID</code><a class="copiable-link" href="#index-PPID"> ¶</a></span></dt> |
| <dd><p>The process <small class="sc">ID</small> of the shell’s parent process. This variable |
| is readonly. |
| </p> |
| </dd> |
| <dt><a id="index-PROMPT_005fCOMMAND"></a><span><code class="code">PROMPT_COMMAND</code><a class="copiable-link" href="#index-PROMPT_005fCOMMAND"> ¶</a></span></dt> |
| <dd><p>If this variable is set, and is an array, |
| the value of each set element is interpreted as a command to execute |
| before printing the primary prompt (<code class="env">$PS1</code>). |
| If this is set but not an array variable, |
| its value is used as a command to execute instead. |
| </p> |
| </dd> |
| <dt><a id="index-PROMPT_005fDIRTRIM"></a><span><code class="code">PROMPT_DIRTRIM</code><a class="copiable-link" href="#index-PROMPT_005fDIRTRIM"> ¶</a></span></dt> |
| <dd><p>If set to a number greater than zero, the value is used as the number of |
| trailing directory components to retain when expanding the <code class="code">\w</code> and |
| <code class="code">\W</code> prompt string escapes (see <a class="pxref" href="#Controlling-the-Prompt">Controlling the Prompt</a>). |
| Characters removed are replaced with an ellipsis. |
| </p> |
| </dd> |
| <dt><a id="index-PS0"></a><span><code class="code">PS0</code><a class="copiable-link" href="#index-PS0"> ¶</a></span></dt> |
| <dd><p>The value of this parameter is expanded like <code class="env">PS1</code> |
| and displayed by interactive shells after reading a command |
| and before the command is executed. |
| </p> |
| </dd> |
| <dt><a id="index-PS3"></a><span><code class="code">PS3</code><a class="copiable-link" href="#index-PS3"> ¶</a></span></dt> |
| <dd><p>The value of this variable is used as the prompt for the |
| <code class="code">select</code> command. If this variable is not set, the |
| <code class="code">select</code> command prompts with ‘<samp class="samp">#? </samp>’ |
| </p> |
| </dd> |
| <dt><a id="index-PS4"></a><span><code class="code">PS4</code><a class="copiable-link" href="#index-PS4"> ¶</a></span></dt> |
| <dd><p>The value of this parameter is expanded like <code class="env">PS1</code> |
| and the expanded value is the prompt printed before the command line |
| is echoed when the <samp class="option">-x</samp> option is set (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>). |
| The first character of the expanded value is replicated multiple times, |
| as necessary, to indicate multiple levels of indirection. |
| The default is ‘<samp class="samp">+ </samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-PWD"></a><span><code class="code">PWD</code><a class="copiable-link" href="#index-PWD"> ¶</a></span></dt> |
| <dd><p>The current working directory as set by the <code class="code">cd</code> builtin. |
| </p> |
| </dd> |
| <dt><a id="index-RANDOM"></a><span><code class="code">RANDOM</code><a class="copiable-link" href="#index-RANDOM"> ¶</a></span></dt> |
| <dd><p>Each time this parameter is referenced, it expands to a random integer |
| between 0 and 32767. Assigning a value to this |
| variable seeds the random number generator. |
| If <code class="env">RANDOM</code> |
| is unset, it loses its special properties, even if it is |
| subsequently reset. |
| </p> |
| </dd> |
| <dt><a id="index-READLINE_005fARGUMENT"></a><span><code class="code">READLINE_ARGUMENT</code><a class="copiable-link" href="#index-READLINE_005fARGUMENT"> ¶</a></span></dt> |
| <dd><p>Any numeric argument given to a Readline command that was defined using |
| ‘<samp class="samp">bind -x</samp>’ (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a> |
| when it was invoked. |
| </p> |
| </dd> |
| <dt><a id="index-READLINE_005fLINE"></a><span><code class="code">READLINE_LINE</code><a class="copiable-link" href="#index-READLINE_005fLINE"> ¶</a></span></dt> |
| <dd><p>The contents of the Readline line buffer, for use |
| with ‘<samp class="samp">bind -x</samp>’ (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>). |
| </p> |
| </dd> |
| <dt><a id="index-READLINE_005fMARK"></a><span><code class="code">READLINE_MARK</code><a class="copiable-link" href="#index-READLINE_005fMARK"> ¶</a></span></dt> |
| <dd><p>The position of the <em class="dfn">mark</em> (saved insertion point) in the |
| Readline line buffer, for use |
| with ‘<samp class="samp">bind -x</samp>’ (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>). |
| The characters between the insertion point and the mark are often |
| called the <em class="dfn">region</em>. |
| </p> |
| </dd> |
| <dt><a id="index-READLINE_005fPOINT"></a><span><code class="code">READLINE_POINT</code><a class="copiable-link" href="#index-READLINE_005fPOINT"> ¶</a></span></dt> |
| <dd><p>The position of the insertion point in the Readline line buffer, for use |
| with ‘<samp class="samp">bind -x</samp>’ (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>). |
| </p> |
| </dd> |
| <dt><a id="index-REPLY"></a><span><code class="code">REPLY</code><a class="copiable-link" href="#index-REPLY"> ¶</a></span></dt> |
| <dd><p>The default variable for the <code class="code">read</code> builtin. |
| </p> |
| </dd> |
| <dt><a id="index-SECONDS"></a><span><code class="code">SECONDS</code><a class="copiable-link" href="#index-SECONDS"> ¶</a></span></dt> |
| <dd><p>This variable expands to the number of seconds since the shell was started. |
| Assignment to this variable resets the count to the value assigned, and the |
| expanded value becomes the value assigned plus the number of seconds |
| since the assignment. |
| The number of seconds at shell invocation and the current time are always |
| determined by querying the system clock. |
| If <code class="env">SECONDS</code> |
| is unset, it loses its special properties, |
| even if it is subsequently reset. |
| </p> |
| </dd> |
| <dt><a id="index-SHELL"></a><span><code class="code">SHELL</code><a class="copiable-link" href="#index-SHELL"> ¶</a></span></dt> |
| <dd><p>This environment variable expands to the full pathname to the shell. |
| If it is not set when the shell starts, |
| Bash assigns to it the full pathname of the current user’s login shell. |
| </p> |
| </dd> |
| <dt><a id="index-SHELLOPTS"></a><span><code class="code">SHELLOPTS</code><a class="copiable-link" href="#index-SHELLOPTS"> ¶</a></span></dt> |
| <dd><p>A colon-separated list of enabled shell options. Each word in |
| the list is a valid argument for the <samp class="option">-o</samp> option to the |
| <code class="code">set</code> builtin command (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>). |
| The options appearing in <code class="env">SHELLOPTS</code> are those reported |
| as ‘<samp class="samp">on</samp>’ by ‘<samp class="samp">set -o</samp>’. |
| If this variable is in the environment when Bash |
| starts up, each shell option in the list will be enabled before |
| reading any startup files. This variable is readonly. |
| </p> |
| </dd> |
| <dt><a id="index-SHLVL"></a><span><code class="code">SHLVL</code><a class="copiable-link" href="#index-SHLVL"> ¶</a></span></dt> |
| <dd><p>Incremented by one each time a new instance of Bash is started. This is |
| intended to be a count of how deeply your Bash shells are nested. |
| </p> |
| </dd> |
| <dt><a id="index-SRANDOM"></a><span><code class="code">SRANDOM</code><a class="copiable-link" href="#index-SRANDOM"> ¶</a></span></dt> |
| <dd><p>This variable expands to a 32-bit pseudo-random number each time it is |
| referenced. The random number generator is not linear on systems that |
| support <samp class="file">/dev/urandom</samp> or <code class="code">arc4random</code>, so each returned number |
| has no relationship to the numbers preceding it. |
| The random number generator cannot be seeded, so assignments to this |
| variable have no effect. |
| If <code class="env">SRANDOM</code> |
| is unset, it loses its special properties, |
| even if it is subsequently reset. |
| </p> |
| </dd> |
| <dt><a id="index-TIMEFORMAT"></a><span><code class="code">TIMEFORMAT</code><a class="copiable-link" href="#index-TIMEFORMAT"> ¶</a></span></dt> |
| <dd><p>The value of this parameter is used as a format string specifying |
| how the timing information for pipelines prefixed with the <code class="code">time</code> |
| reserved word should be displayed. |
| The ‘<samp class="samp">%</samp>’ character introduces an |
| escape sequence that is expanded to a time value or other |
| information. |
| The escape sequences and their meanings are as |
| follows; the braces denote optional portions. |
| </p> |
| <dl class="table"> |
| <dt><code class="code">%%</code></dt> |
| <dd><p>A literal ‘<samp class="samp">%</samp>’. |
| </p> |
| </dd> |
| <dt><code class="code">%[<var class="var">p</var>][l]R</code></dt> |
| <dd><p>The elapsed time in seconds. |
| </p> |
| </dd> |
| <dt><code class="code">%[<var class="var">p</var>][l]U</code></dt> |
| <dd><p>The number of CPU seconds spent in user mode. |
| </p> |
| </dd> |
| <dt><code class="code">%[<var class="var">p</var>][l]S</code></dt> |
| <dd><p>The number of CPU seconds spent in system mode. |
| </p> |
| </dd> |
| <dt><code class="code">%P</code></dt> |
| <dd><p>The CPU percentage, computed as (%U + %S) / %R. |
| </p></dd> |
| </dl> |
| |
| <p>The optional <var class="var">p</var> is a digit specifying the precision, the number of |
| fractional digits after a decimal point. |
| A value of 0 causes no decimal point or fraction to be output. |
| At most three places after the decimal point may be specified; values |
| of <var class="var">p</var> greater than 3 are changed to 3. |
| If <var class="var">p</var> is not specified, the value 3 is used. |
| </p> |
| <p>The optional <code class="code">l</code> specifies a longer format, including minutes, of |
| the form <var class="var">MM</var>m<var class="var">SS</var>.<var class="var">FF</var>s. |
| The value of <var class="var">p</var> determines whether or not the fraction is included. |
| </p> |
| <p>If this variable is not set, Bash acts as if it had the value |
| </p><div class="example"> |
| <pre class="example-preformatted"><code class="code">$'\nreal\t%3lR\nuser\t%3lU\nsys\t%3lS'</code> |
| </pre></div> |
| <p>If the value is null, no timing information is displayed. |
| A trailing newline is added when the format string is displayed. |
| </p> |
| </dd> |
| <dt><a id="index-TMOUT"></a><span><code class="code">TMOUT</code><a class="copiable-link" href="#index-TMOUT"> ¶</a></span></dt> |
| <dd><p>If set to a value greater than zero, <code class="code">TMOUT</code> is treated as the |
| default timeout for the <code class="code">read</code> builtin (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>). |
| The <code class="code">select</code> command (see <a class="pxref" href="#Conditional-Constructs">Conditional Constructs</a>) terminates |
| if input does not arrive after <code class="code">TMOUT</code> seconds when input is coming |
| from a terminal. |
| </p> |
| <p>In an interactive shell, the value is interpreted as |
| the number of seconds to wait for a line of input after issuing |
| the primary prompt. |
| Bash |
| terminates after waiting for that number of seconds if a complete |
| line of input does not arrive. |
| </p> |
| </dd> |
| <dt><a id="index-TMPDIR"></a><span><code class="code">TMPDIR</code><a class="copiable-link" href="#index-TMPDIR"> ¶</a></span></dt> |
| <dd><p>If set, Bash uses its value as the name of a directory in which |
| Bash creates temporary files for the shell’s use. |
| </p> |
| </dd> |
| <dt><a id="index-UID"></a><span><code class="code">UID</code><a class="copiable-link" href="#index-UID"> ¶</a></span></dt> |
| <dd><p>The numeric real user id of the current user. This variable is readonly. |
| </p> |
| </dd> |
| </dl> |
| |
| <hr> |
| </div> |
| </div> |
| <div class="chapter-level-extent" id="Bash-Features"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Job-Control" accesskey="n" rel="next">Job Control</a>, Previous: <a href="#Shell-Variables" accesskey="p" rel="prev">Shell Variables</a>, Up: <a href="#Top" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h2 class="chapter" id="Bash-Features-2"><span>6 Bash Features<a class="copiable-link" href="#Bash-Features-2"> ¶</a></span></h2> |
| |
| <p>This chapter describes features unique to Bash. |
| </p> |
| |
| <ul class="mini-toc"> |
| <li><a href="#Invoking-Bash" accesskey="1">Invoking Bash</a></li> |
| <li><a href="#Bash-Startup-Files" accesskey="2">Bash Startup Files</a></li> |
| <li><a href="#Interactive-Shells" accesskey="3">Interactive Shells</a></li> |
| <li><a href="#Bash-Conditional-Expressions" accesskey="4">Bash Conditional Expressions</a></li> |
| <li><a href="#Shell-Arithmetic" accesskey="5">Shell Arithmetic</a></li> |
| <li><a href="#Aliases" accesskey="6">Aliases</a></li> |
| <li><a href="#Arrays" accesskey="7">Arrays</a></li> |
| <li><a href="#The-Directory-Stack" accesskey="8">The Directory Stack</a></li> |
| <li><a href="#Controlling-the-Prompt" accesskey="9">Controlling the Prompt</a></li> |
| <li><a href="#The-Restricted-Shell">The Restricted Shell</a></li> |
| <li><a href="#Bash-POSIX-Mode">Bash POSIX Mode</a></li> |
| <li><a href="#Shell-Compatibility-Mode">Shell Compatibility Mode</a></li> |
| </ul> |
| <hr> |
| <div class="section-level-extent" id="Invoking-Bash"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Bash-Startup-Files" accesskey="n" rel="next">Bash Startup Files</a>, Up: <a href="#Bash-Features" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Invoking-Bash-1"><span>6.1 Invoking Bash<a class="copiable-link" href="#Invoking-Bash-1"> ¶</a></span></h3> |
| |
| <div class="example"> |
| <pre class="example-preformatted">bash [long-opt] [-ir] [-abefhkmnptuvxdBCDHP] [-o <var class="var">option</var>] |
| [-O <var class="var">shopt_option</var>] [<var class="var">argument</var> ...] |
| bash [long-opt] [-abefhkmnptuvxdBCDHP] [-o <var class="var">option</var>] |
| [-O <var class="var">shopt_option</var>] -c <var class="var">string</var> [<var class="var">argument</var> ...] |
| bash [long-opt] -s [-abefhkmnptuvxdBCDHP] [-o <var class="var">option</var>] |
| [-O <var class="var">shopt_option</var>] [<var class="var">argument</var> ...] |
| </pre></div> |
| |
| <p>All of the single-character options used with the <code class="code">set</code> builtin |
| (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>) can be used as options when the shell is invoked. |
| In addition, there are several multi-character |
| options that you can use. These options must appear on the command |
| line before the single-character options to be recognized. |
| </p> |
| <dl class="table"> |
| <dt><code class="code">--debugger</code></dt> |
| <dd><p>Arrange for the debugger profile to be executed before the shell |
| starts. Turns on extended debugging mode (see <a class="ref" href="#The-Shopt-Builtin">The Shopt Builtin</a> |
| for a description of the <code class="code">extdebug</code> option to the <code class="code">shopt</code> |
| builtin). |
| </p> |
| </dd> |
| <dt><code class="code">--dump-po-strings</code></dt> |
| <dd><p>A list of all double-quoted strings preceded by ‘<samp class="samp">$</samp>’ |
| is printed on the standard output |
| in the <small class="sc">GNU</small> <code class="code">gettext</code> PO (portable object) file format. |
| Equivalent to <samp class="option">-D</samp> except for the output format. |
| </p> |
| </dd> |
| <dt><code class="code">--dump-strings</code></dt> |
| <dd><p>Equivalent to <samp class="option">-D</samp>. |
| </p> |
| </dd> |
| <dt><code class="code">--help</code></dt> |
| <dd><p>Display a usage message on standard output and exit successfully. |
| </p> |
| </dd> |
| <dt><code class="code">--init-file <var class="var">filename</var></code></dt> |
| <dt><code class="code">--rcfile <var class="var">filename</var></code></dt> |
| <dd><p>Execute commands from <var class="var">filename</var> (instead of <samp class="file">~/.bashrc</samp>) |
| in an interactive shell. |
| </p> |
| </dd> |
| <dt><code class="code">--login</code></dt> |
| <dd><p>Equivalent to <samp class="option">-l</samp>. |
| </p> |
| </dd> |
| <dt><code class="code">--noediting</code></dt> |
| <dd><p>Do not use the <small class="sc">GNU</small> Readline library (see <a class="pxref" href="#Command-Line-Editing">Command Line Editing</a>) |
| to read command lines when the shell is interactive. |
| </p> |
| </dd> |
| <dt><code class="code">--noprofile</code></dt> |
| <dd><p>Don’t load the system-wide startup file <samp class="file">/etc/profile</samp> |
| or any of the personal initialization files |
| <samp class="file">~/.bash_profile</samp>, <samp class="file">~/.bash_login</samp>, or <samp class="file">~/.profile</samp> |
| when Bash is invoked as a login shell. |
| </p> |
| </dd> |
| <dt><code class="code">--norc</code></dt> |
| <dd><p>Don’t read the <samp class="file">~/.bashrc</samp> initialization file in an |
| interactive shell. This is on by default if the shell is |
| invoked as <code class="code">sh</code>. |
| </p> |
| </dd> |
| <dt><code class="code">--posix</code></dt> |
| <dd><p>Change the behavior of Bash where the default operation differs |
| from the <small class="sc">POSIX</small> standard to match the standard. This |
| is intended to make Bash behave as a strict superset of that |
| standard. See <a class="xref" href="#Bash-POSIX-Mode">Bash POSIX Mode</a>, for a description of the Bash |
| <small class="sc">POSIX</small> mode. |
| </p> |
| </dd> |
| <dt><code class="code">--restricted</code></dt> |
| <dd><p>Make the shell a restricted shell (see <a class="pxref" href="#The-Restricted-Shell">The Restricted Shell</a>). |
| </p> |
| </dd> |
| <dt><code class="code">--verbose</code></dt> |
| <dd><p>Equivalent to <samp class="option">-v</samp>. Print shell input lines as they’re read. |
| </p> |
| </dd> |
| <dt><code class="code">--version</code></dt> |
| <dd><p>Show version information for this instance of |
| Bash on the standard output and exit successfully. |
| </p></dd> |
| </dl> |
| |
| <p>There are several single-character options that may be supplied at |
| invocation which are not available with the <code class="code">set</code> builtin. |
| </p> |
| <dl class="table"> |
| <dt><code class="code">-c</code></dt> |
| <dd><p>Read and execute commands from the first non-option argument |
| <var class="var">command_string</var>, then exit. |
| If there are arguments after the <var class="var">command_string</var>, |
| the first argument is assigned to <code class="code">$0</code> |
| and any remaining arguments are assigned to the positional parameters. |
| The assignment to <code class="code">$0</code> sets the name of the shell, which is used |
| in warning and error messages. |
| </p> |
| </dd> |
| <dt><code class="code">-i</code></dt> |
| <dd><p>Force the shell to run interactively. Interactive shells are |
| described in <a class="ref" href="#Interactive-Shells">Interactive Shells</a>. |
| </p> |
| </dd> |
| <dt><code class="code">-l</code></dt> |
| <dd><p>Make this shell act as if it had been directly invoked by login. |
| When the shell is interactive, this is equivalent to starting a |
| login shell with ‘<samp class="samp">exec -l bash</samp>’. |
| When the shell is not interactive, the login shell startup files will |
| be executed. |
| ‘<samp class="samp">exec bash -l</samp>’ or ‘<samp class="samp">exec bash --login</samp>’ |
| will replace the current shell with a Bash login shell. |
| See <a class="xref" href="#Bash-Startup-Files">Bash Startup Files</a>, for a description of the special behavior |
| of a login shell. |
| </p> |
| </dd> |
| <dt><code class="code">-r</code></dt> |
| <dd><p>Make the shell a restricted shell (see <a class="pxref" href="#The-Restricted-Shell">The Restricted Shell</a>). |
| </p> |
| </dd> |
| <dt><code class="code">-s</code></dt> |
| <dd><p>If this option is present, or if no arguments remain after option |
| processing, then commands are read from the standard input. |
| This option allows the positional parameters to be set |
| when invoking an interactive shell or when reading input |
| through a pipe. |
| </p> |
| </dd> |
| <dt><code class="code">-D</code></dt> |
| <dd><p>A list of all double-quoted strings preceded by ‘<samp class="samp">$</samp>’ |
| is printed on the standard output. |
| These are the strings that |
| are subject to language translation when the current locale |
| is not <code class="code">C</code> or <code class="code">POSIX</code> (see <a class="pxref" href="#Locale-Translation">Locale-Specific Translation</a>). |
| This implies the <samp class="option">-n</samp> option; no commands will be executed. |
| </p> |
| </dd> |
| <dt><code class="code">[-+]O [<var class="var">shopt_option</var>]</code></dt> |
| <dd><p><var class="var">shopt_option</var> is one of the shell options accepted by the |
| <code class="code">shopt</code> builtin (see <a class="pxref" href="#The-Shopt-Builtin">The Shopt Builtin</a>). |
| If <var class="var">shopt_option</var> is present, <samp class="option">-O</samp> sets the value of that option; |
| <samp class="option">+O</samp> unsets it. |
| If <var class="var">shopt_option</var> is not supplied, the names and values of the shell |
| options accepted by <code class="code">shopt</code> are printed on the standard output. |
| If the invocation option is <samp class="option">+O</samp>, the output is displayed in a format |
| that may be reused as input. |
| </p> |
| </dd> |
| <dt><code class="code">--</code></dt> |
| <dd><p>A <code class="code">--</code> signals the end of options and disables further option |
| processing. |
| Any arguments after the <code class="code">--</code> are treated as filenames and arguments. |
| </p></dd> |
| </dl> |
| |
| <a class="index-entry-id" id="index-login-shell"></a> |
| <p>A <em class="emph">login</em> shell is one whose first character of argument zero is |
| ‘<samp class="samp">-</samp>’, or one invoked with the <samp class="option">--login</samp> option. |
| </p> |
| <a class="index-entry-id" id="index-interactive-shell"></a> |
| <p>An <em class="emph">interactive</em> shell is one started without non-option arguments, |
| unless <samp class="option">-s</samp> is specified, |
| without specifying the <samp class="option">-c</samp> option, and whose input and output are both |
| connected to terminals (as determined by <code class="code">isatty(3)</code>), or one |
| started with the <samp class="option">-i</samp> option. See <a class="xref" href="#Interactive-Shells">Interactive Shells</a>, for more |
| information. |
| </p> |
| <p>If arguments remain after option processing, and neither the |
| <samp class="option">-c</samp> nor the <samp class="option">-s</samp> |
| option has been supplied, the first argument is assumed to |
| be the name of a file containing shell commands (see <a class="pxref" href="#Shell-Scripts">Shell Scripts</a>). |
| When Bash is invoked in this fashion, <code class="code">$0</code> |
| is set to the name of the file, and the positional parameters |
| are set to the remaining arguments. |
| Bash reads and executes commands from this file, then exits. |
| Bash’s exit status is the exit status of the last command executed |
| in the script. If no commands are executed, the exit status is 0. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Bash-Startup-Files"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Interactive-Shells" accesskey="n" rel="next">Interactive Shells</a>, Previous: <a href="#Invoking-Bash" accesskey="p" rel="prev">Invoking Bash</a>, Up: <a href="#Bash-Features" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Bash-Startup-Files-1"><span>6.2 Bash Startup Files<a class="copiable-link" href="#Bash-Startup-Files-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-startup-files"></a> |
| |
| <p>This section describes how Bash executes its startup files. |
| If any of the files exist but cannot be read, Bash reports an error. |
| Tildes are expanded in filenames as described above under |
| Tilde Expansion (see <a class="pxref" href="#Tilde-Expansion">Tilde Expansion</a>). |
| </p> |
| <p>Interactive shells are described in <a class="ref" href="#Interactive-Shells">Interactive Shells</a>. |
| </p> |
| <h4 class="subsubheading" id="Invoked-as-an-interactive-login-shell_002c-or-with-_002d_002dlogin"><span>Invoked as an interactive login shell, or with <samp class="option">--login</samp><a class="copiable-link" href="#Invoked-as-an-interactive-login-shell_002c-or-with-_002d_002dlogin"> ¶</a></span></h4> |
| |
| <p>When Bash is invoked as an interactive login shell, or as a |
| non-interactive shell with the <samp class="option">--login</samp> option, it first reads and |
| executes commands from the file <samp class="file">/etc/profile</samp>, if that file exists. |
| After reading that file, it looks for <samp class="file">~/.bash_profile</samp>, |
| <samp class="file">~/.bash_login</samp>, and <samp class="file">~/.profile</samp>, in that order, and reads |
| and executes commands from the first one that exists and is readable. |
| The <samp class="option">--noprofile</samp> option may be used when the shell is started to |
| inhibit this behavior. |
| </p> |
| <p>When an interactive login shell exits, |
| or a non-interactive login shell executes the <code class="code">exit</code> builtin command, |
| Bash reads and executes commands from |
| the file <samp class="file">~/.bash_logout</samp>, if it exists. |
| </p> |
| <h4 class="subsubheading" id="Invoked-as-an-interactive-non_002dlogin-shell"><span>Invoked as an interactive non-login shell<a class="copiable-link" href="#Invoked-as-an-interactive-non_002dlogin-shell"> ¶</a></span></h4> |
| |
| <p>When an interactive shell that is not a login shell is started, Bash |
| reads and executes commands from <samp class="file">~/.bashrc</samp>, if that file exists. |
| This may be inhibited by using the <samp class="option">--norc</samp> option. |
| The <samp class="option">--rcfile <var class="var">file</var></samp> option will force Bash to read and |
| execute commands from <var class="var">file</var> instead of <samp class="file">~/.bashrc</samp>. |
| </p> |
| <p>So, typically, your <samp class="file">~/.bash_profile</samp> contains the line |
| </p><div class="example"> |
| <pre class="example-preformatted"><code class="code">if [ -f ~/.bashrc ]; then . ~/.bashrc; fi</code> |
| </pre></div> |
| <p>after (or before) any login-specific initializations. |
| </p> |
| <h4 class="subsubheading" id="Invoked-non_002dinteractively"><span>Invoked non-interactively<a class="copiable-link" href="#Invoked-non_002dinteractively"> ¶</a></span></h4> |
| |
| <p>When Bash is started non-interactively, to run a shell script, |
| for example, it looks for the variable <code class="env">BASH_ENV</code> in the environment, |
| expands its value if it appears there, and uses the expanded value as |
| the name of a file to read and execute. Bash behaves as if the |
| following command were executed: |
| </p><div class="example"> |
| <pre class="example-preformatted"><code class="code">if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi</code> |
| </pre></div> |
| <p>but the value of the <code class="env">PATH</code> variable is not used to search for the |
| filename. |
| </p> |
| <p>As noted above, if a non-interactive shell is invoked with the |
| <samp class="option">--login</samp> option, Bash attempts to read and execute commands from the |
| login shell startup files. |
| </p> |
| <h4 class="subsubheading" id="Invoked-with-name-sh"><span>Invoked with name <code class="code">sh</code><a class="copiable-link" href="#Invoked-with-name-sh"> ¶</a></span></h4> |
| |
| <p>If Bash is invoked with the name <code class="code">sh</code>, it tries to mimic the |
| startup behavior of historical versions of <code class="code">sh</code> as closely as |
| possible, while conforming to the <small class="sc">POSIX</small> standard as well. |
| </p> |
| <p>When invoked as an interactive login shell, or as a non-interactive |
| shell with the <samp class="option">--login</samp> option, it first attempts to read |
| and execute commands from <samp class="file">/etc/profile</samp> and <samp class="file">~/.profile</samp>, in |
| that order. |
| The <samp class="option">--noprofile</samp> option may be used to inhibit this behavior. |
| When invoked as an interactive shell with the name <code class="code">sh</code>, Bash |
| looks for the variable <code class="env">ENV</code>, expands its value if it is defined, |
| and uses the expanded value as the name of a file to read and execute. |
| Since a shell invoked as <code class="code">sh</code> does not attempt to read and execute |
| commands from any other startup files, the <samp class="option">--rcfile</samp> option has |
| no effect. |
| A non-interactive shell invoked with the name <code class="code">sh</code> does not attempt |
| to read any other startup files. |
| </p> |
| <p>When invoked as <code class="code">sh</code>, Bash enters <small class="sc">POSIX</small> mode after |
| the startup files are read. |
| </p> |
| <h4 class="subsubheading" id="Invoked-in-posix-mode"><span>Invoked in <small class="sc">POSIX</small> mode<a class="copiable-link" href="#Invoked-in-posix-mode"> ¶</a></span></h4> |
| |
| <p>When Bash is started in <small class="sc">POSIX</small> mode, as with the |
| <samp class="option">--posix</samp> command line option, it follows the <small class="sc">POSIX</small> standard |
| for startup files. |
| In this mode, interactive shells expand the <code class="env">ENV</code> variable |
| and commands are read and executed from the file whose name is the |
| expanded value. |
| No other startup files are read. |
| </p> |
| <h4 class="subsubheading" id="Invoked-by-remote-shell-daemon"><span>Invoked by remote shell daemon<a class="copiable-link" href="#Invoked-by-remote-shell-daemon"> ¶</a></span></h4> |
| |
| <p>Bash attempts to determine when it is being run with its standard input |
| connected to a network connection, as when executed by |
| the historical remote shell daemon, usually <code class="code">rshd</code>, |
| or the secure shell daemon <code class="code">sshd</code>. |
| If Bash |
| determines it is being run non-interactively in this fashion, |
| it reads and executes commands from <samp class="file">~/.bashrc</samp>, if that |
| file exists and is readable. |
| It will not do this if invoked as <code class="code">sh</code>. |
| The <samp class="option">--norc</samp> option may be used to inhibit this behavior, and the |
| <samp class="option">--rcfile</samp> option may be used to force another file to be read, but |
| neither <code class="code">rshd</code> nor <code class="code">sshd</code> generally invoke the shell with those |
| options or allow them to be specified. |
| </p> |
| <h4 class="subsubheading" id="Invoked-with-unequal-effective-and-real-uid_002fgids"><span>Invoked with unequal effective and real <small class="sc">UID/GID</small>s<a class="copiable-link" href="#Invoked-with-unequal-effective-and-real-uid_002fgids"> ¶</a></span></h4> |
| |
| <p>If Bash is started with the effective user (group) id not equal to the |
| real user (group) id, and the <samp class="option">-p</samp> option is not supplied, no startup |
| files are read, shell functions are not inherited from the environment, |
| the <code class="env">SHELLOPTS</code>, <code class="env">BASHOPTS</code>, <code class="env">CDPATH</code>, and <code class="env">GLOBIGNORE</code> |
| variables, if they appear in the environment, are ignored, and the effective |
| user id is set to the real user id. |
| If the <samp class="option">-p</samp> option is supplied at invocation, the startup behavior is |
| the same, but the effective user id is not reset. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Interactive-Shells"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Bash-Conditional-Expressions" accesskey="n" rel="next">Bash Conditional Expressions</a>, Previous: <a href="#Bash-Startup-Files" accesskey="p" rel="prev">Bash Startup Files</a>, Up: <a href="#Bash-Features" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Interactive-Shells-1"><span>6.3 Interactive Shells<a class="copiable-link" href="#Interactive-Shells-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-interactive-shell-1"></a> |
| <a class="index-entry-id" id="index-shell_002c-interactive"></a> |
| |
| |
| <ul class="mini-toc"> |
| <li><a href="#What-is-an-Interactive-Shell_003f" accesskey="1">What is an Interactive Shell?</a></li> |
| <li><a href="#Is-this-Shell-Interactive_003f" accesskey="2">Is this Shell Interactive?</a></li> |
| <li><a href="#Interactive-Shell-Behavior" accesskey="3">Interactive Shell Behavior</a></li> |
| </ul> |
| <hr> |
| <div class="subsection-level-extent" id="What-is-an-Interactive-Shell_003f"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Is-this-Shell-Interactive_003f" accesskey="n" rel="next">Is this Shell Interactive?</a>, Up: <a href="#Interactive-Shells" accesskey="u" rel="up">Interactive Shells</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="What-is-an-Interactive-Shell_003f-1"><span>6.3.1 What is an Interactive Shell?<a class="copiable-link" href="#What-is-an-Interactive-Shell_003f-1"> ¶</a></span></h4> |
| |
| <p>An interactive shell |
| is one started without non-option arguments |
| (unless <samp class="option">-s</samp> is specified) |
| and without specifying the <samp class="option">-c</samp> option, |
| whose input and error output are both |
| connected to terminals (as determined by <code class="code">isatty(3)</code>), |
| or one started with the <samp class="option">-i</samp> option. |
| </p> |
| <p>An interactive shell generally reads from and writes to a user’s |
| terminal. |
| </p> |
| <p>The <samp class="option">-s</samp> invocation option may be used to set the positional parameters |
| when an interactive shell is started. |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Is-this-Shell-Interactive_003f"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Interactive-Shell-Behavior" accesskey="n" rel="next">Interactive Shell Behavior</a>, Previous: <a href="#What-is-an-Interactive-Shell_003f" accesskey="p" rel="prev">What is an Interactive Shell?</a>, Up: <a href="#Interactive-Shells" accesskey="u" rel="up">Interactive Shells</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Is-this-Shell-Interactive_003f-1"><span>6.3.2 Is this Shell Interactive?<a class="copiable-link" href="#Is-this-Shell-Interactive_003f-1"> ¶</a></span></h4> |
| |
| <p>To determine within a startup script whether or not Bash is |
| running interactively, |
| test the value of the ‘<samp class="samp">-</samp>’ special parameter. |
| It contains <code class="code">i</code> when the shell is interactive. For example: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">case "$-" in |
| *i*) echo This shell is interactive ;; |
| *) echo This shell is not interactive ;; |
| esac |
| </pre></div> |
| |
| <p>Alternatively, startup scripts may examine the variable |
| <code class="env">PS1</code>; it is unset in non-interactive shells, and set in |
| interactive shells. Thus: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">if [ -z "$PS1" ]; then |
| echo This shell is not interactive |
| else |
| echo This shell is interactive |
| fi |
| </pre></div> |
| |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Interactive-Shell-Behavior"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Is-this-Shell-Interactive_003f" accesskey="p" rel="prev">Is this Shell Interactive?</a>, Up: <a href="#Interactive-Shells" accesskey="u" rel="up">Interactive Shells</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Interactive-Shell-Behavior-1"><span>6.3.3 Interactive Shell Behavior<a class="copiable-link" href="#Interactive-Shell-Behavior-1"> ¶</a></span></h4> |
| |
| <p>When the shell is running interactively, it changes its behavior in |
| several ways. |
| </p> |
| <ol class="enumerate"> |
| <li> Startup files are read and executed as described in <a class="ref" href="#Bash-Startup-Files">Bash Startup Files</a>. |
| |
| </li><li> Job Control (see <a class="pxref" href="#Job-Control">Job Control</a>) is enabled by default. When job |
| control is in effect, Bash ignores the keyboard-generated job control |
| signals <code class="code">SIGTTIN</code>, <code class="code">SIGTTOU</code>, and <code class="code">SIGTSTP</code>. |
| |
| </li><li> Bash expands and displays <code class="env">PS1</code> before reading the first line |
| of a command, and expands and displays <code class="env">PS2</code> before reading the |
| second and subsequent lines of a multi-line command. |
| Bash expands and displays <code class="env">PS0</code> after it reads a command but before |
| executing it. |
| See <a class="ref" href="#Controlling-the-Prompt">Controlling the Prompt</a>, for a complete list of prompt |
| string escape sequences. |
| |
| </li><li> Bash executes the values of the set elements of the <code class="env">PROMPT_COMMAND</code> |
| array variable as commands before printing the primary prompt, <code class="env">$PS1</code> |
| (see <a class="pxref" href="#Bash-Variables">Bash Variables</a>). |
| |
| </li><li> Readline (see <a class="pxref" href="#Command-Line-Editing">Command Line Editing</a>) is used to read commands from |
| the user’s terminal. |
| |
| </li><li> Bash inspects the value of the <code class="code">ignoreeof</code> option to <code class="code">set -o</code> |
| instead of exiting immediately when it receives an <code class="code">EOF</code> on its |
| standard input when reading a command (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>). |
| |
| </li><li> Command history (see <a class="pxref" href="#Bash-History-Facilities">Bash History Facilities</a>) |
| and history expansion (see <a class="pxref" href="#History-Interaction">History Expansion</a>) |
| are enabled by default. |
| Bash will save the command history to the file named by <code class="env">$HISTFILE</code> |
| when a shell with history enabled exits. |
| |
| </li><li> Alias expansion (see <a class="pxref" href="#Aliases">Aliases</a>) is performed by default. |
| |
| </li><li> In the absence of any traps, Bash ignores <code class="code">SIGTERM</code> |
| (see <a class="pxref" href="#Signals">Signals</a>). |
| |
| </li><li> In the absence of any traps, <code class="code">SIGINT</code> is caught and handled |
| (see <a class="pxref" href="#Signals">Signals</a>). |
| <code class="code">SIGINT</code> will interrupt some shell builtins. |
| |
| </li><li> An interactive login shell sends a <code class="code">SIGHUP</code> to all jobs on exit |
| if the <code class="code">huponexit</code> shell option has been enabled (see <a class="pxref" href="#Signals">Signals</a>). |
| |
| </li><li> The <samp class="option">-n</samp> invocation option is ignored, and ‘<samp class="samp">set -n</samp>’ has |
| no effect (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>). |
| |
| </li><li> Bash will check for mail periodically, depending on the values of the |
| <code class="env">MAIL</code>, <code class="env">MAILPATH</code>, and <code class="env">MAILCHECK</code> shell variables |
| (see <a class="pxref" href="#Bash-Variables">Bash Variables</a>). |
| |
| </li><li> Expansion errors due to references to unbound shell variables after |
| ‘<samp class="samp">set -u</samp>’ has been enabled will not cause the shell to exit |
| (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>). |
| |
| </li><li> The shell will not exit on expansion errors caused by <var class="var">var</var> being unset |
| or null in <code class="code">${<var class="var">var</var>:?<var class="var">word</var>}</code> expansions |
| (see <a class="pxref" href="#Shell-Parameter-Expansion">Shell Parameter Expansion</a>). |
| |
| </li><li> Redirection errors encountered by shell builtins will not cause the |
| shell to exit. |
| |
| </li><li> When running in <small class="sc">POSIX</small> mode, a special builtin returning an error |
| status will not cause the shell to exit (see <a class="pxref" href="#Bash-POSIX-Mode">Bash POSIX Mode</a>). |
| |
| </li><li> A failed <code class="code">exec</code> will not cause the shell to exit |
| (see <a class="pxref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>). |
| |
| </li><li> Parser syntax errors will not cause the shell to exit. |
| |
| </li><li> If the <code class="code">cdspell</code> shell option is enabled, the shell will attempt |
| simple spelling correction for directory arguments to the <code class="code">cd</code> |
| builtin (see the description of the <code class="code">cdspell</code> |
| option to the <code class="code">shopt</code> builtin in <a class="ref" href="#The-Shopt-Builtin">The Shopt Builtin</a>). |
| The <code class="code">cdspell</code> option is only effective in interactive shells. |
| |
| </li><li> The shell will check the value of the <code class="env">TMOUT</code> variable and exit |
| if a command is not read within the specified number of seconds after |
| printing <code class="env">$PS1</code> (see <a class="pxref" href="#Bash-Variables">Bash Variables</a>). |
| |
| </li></ol> |
| |
| <hr> |
| </div> |
| </div> |
| <div class="section-level-extent" id="Bash-Conditional-Expressions"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Shell-Arithmetic" accesskey="n" rel="next">Shell Arithmetic</a>, Previous: <a href="#Interactive-Shells" accesskey="p" rel="prev">Interactive Shells</a>, Up: <a href="#Bash-Features" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Bash-Conditional-Expressions-1"><span>6.4 Bash Conditional Expressions<a class="copiable-link" href="#Bash-Conditional-Expressions-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-expressions_002c-conditional"></a> |
| |
| <p>Conditional expressions are used by the <code class="code">[[</code> compound command |
| (see <a class="pxref" href="#Conditional-Constructs">Conditional Constructs</a>) |
| and the <code class="code">test</code> and <code class="code">[</code> builtin commands |
| (see <a class="pxref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>). |
| The <code class="code">test</code> |
| and <code class="code">[</code> commands determine their behavior based on the number |
| of arguments; see the descriptions of those commands for any other |
| command-specific actions. |
| </p> |
| <p>Expressions may be unary or binary, |
| and are formed from the following primaries. |
| Unary expressions are often used to examine the status of a file. |
| There are string operators and numeric comparison operators as well. |
| Bash handles several filenames specially when they are used in |
| expressions. |
| If the operating system on which Bash is running provides these |
| special files, Bash will use them; otherwise it will emulate them |
| internally with this behavior: |
| If the <var class="var">file</var> argument to one of the primaries is of the form |
| <samp class="file">/dev/fd/<var class="var">N</var></samp>, then file descriptor <var class="var">N</var> is checked. |
| If the <var class="var">file</var> argument to one of the primaries is one of |
| <samp class="file">/dev/stdin</samp>, <samp class="file">/dev/stdout</samp>, or <samp class="file">/dev/stderr</samp>, file |
| descriptor 0, 1, or 2, respectively, is checked. |
| </p> |
| <p>When used with <code class="code">[[</code>, the ‘<samp class="samp"><</samp>’ and ‘<samp class="samp">></samp>’ operators sort |
| lexicographically using the current locale. |
| The <code class="code">test</code> command uses ASCII ordering. |
| </p> |
| <p>Unless otherwise specified, primaries that operate on files follow symbolic |
| links and operate on the target of the link, rather than the link itself. |
| </p> |
| <dl class="table"> |
| <dt><code class="code">-a <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists. |
| </p> |
| </dd> |
| <dt><code class="code">-b <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists and is a block special file. |
| </p> |
| </dd> |
| <dt><code class="code">-c <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists and is a character special file. |
| </p> |
| </dd> |
| <dt><code class="code">-d <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists and is a directory. |
| </p> |
| </dd> |
| <dt><code class="code">-e <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists. |
| </p> |
| </dd> |
| <dt><code class="code">-f <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists and is a regular file. |
| </p> |
| </dd> |
| <dt><code class="code">-g <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists and its set-group-id bit is set. |
| </p> |
| </dd> |
| <dt><code class="code">-h <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists and is a symbolic link. |
| </p> |
| </dd> |
| <dt><code class="code">-k <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists and its "sticky" bit is set. |
| </p> |
| </dd> |
| <dt><code class="code">-p <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists and is a named pipe (FIFO). |
| </p> |
| </dd> |
| <dt><code class="code">-r <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists and is readable. |
| </p> |
| </dd> |
| <dt><code class="code">-s <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists and has a size greater than zero. |
| </p> |
| </dd> |
| <dt><code class="code">-t <var class="var">fd</var></code></dt> |
| <dd><p>True if file descriptor <var class="var">fd</var> is open and refers to a terminal. |
| </p> |
| </dd> |
| <dt><code class="code">-u <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists and its set-user-id bit is set. |
| </p> |
| </dd> |
| <dt><code class="code">-w <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists and is writable. |
| </p> |
| </dd> |
| <dt><code class="code">-x <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists and is executable. |
| </p> |
| </dd> |
| <dt><code class="code">-G <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists and is owned by the effective group id. |
| </p> |
| </dd> |
| <dt><code class="code">-L <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists and is a symbolic link. |
| </p> |
| </dd> |
| <dt><code class="code">-N <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists and has been modified since it was last read. |
| </p> |
| </dd> |
| <dt><code class="code">-O <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists and is owned by the effective user id. |
| </p> |
| </dd> |
| <dt><code class="code">-S <var class="var">file</var></code></dt> |
| <dd><p>True if <var class="var">file</var> exists and is a socket. |
| </p> |
| </dd> |
| <dt><code class="code"><var class="var">file1</var> -ef <var class="var">file2</var></code></dt> |
| <dd><p>True if <var class="var">file1</var> and <var class="var">file2</var> refer to the same device and |
| inode numbers. |
| </p> |
| </dd> |
| <dt><code class="code"><var class="var">file1</var> -nt <var class="var">file2</var></code></dt> |
| <dd><p>True if <var class="var">file1</var> is newer (according to modification date) |
| than <var class="var">file2</var>, or if <var class="var">file1</var> exists and <var class="var">file2</var> does not. |
| </p> |
| </dd> |
| <dt><code class="code"><var class="var">file1</var> -ot <var class="var">file2</var></code></dt> |
| <dd><p>True if <var class="var">file1</var> is older than <var class="var">file2</var>, |
| or if <var class="var">file2</var> exists and <var class="var">file1</var> does not. |
| </p> |
| </dd> |
| <dt><code class="code">-o <var class="var">optname</var></code></dt> |
| <dd><p>True if the shell option <var class="var">optname</var> is enabled. |
| The list of options appears in the description of the <samp class="option">-o</samp> |
| option to the <code class="code">set</code> builtin (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>). |
| </p> |
| </dd> |
| <dt><code class="code">-v <var class="var">varname</var></code></dt> |
| <dd><p>True if the shell variable <var class="var">varname</var> is set (has been assigned a value). |
| </p> |
| </dd> |
| <dt><code class="code">-R <var class="var">varname</var></code></dt> |
| <dd><p>True if the shell variable <var class="var">varname</var> is set and is a name reference. |
| </p> |
| </dd> |
| <dt><code class="code">-z <var class="var">string</var></code></dt> |
| <dd><p>True if the length of <var class="var">string</var> is zero. |
| </p> |
| </dd> |
| <dt><code class="code">-n <var class="var">string</var></code></dt> |
| <dt><code class="code"><var class="var">string</var></code></dt> |
| <dd><p>True if the length of <var class="var">string</var> is non-zero. |
| </p> |
| </dd> |
| <dt><code class="code"><var class="var">string1</var> == <var class="var">string2</var></code></dt> |
| <dt><code class="code"><var class="var">string1</var> = <var class="var">string2</var></code></dt> |
| <dd><p>True if the strings are equal. |
| When used with the <code class="code">[[</code> command, this performs pattern matching as |
| described above (see <a class="pxref" href="#Conditional-Constructs">Conditional Constructs</a>). |
| </p> |
| <p>‘<samp class="samp">=</samp>’ should be used with the <code class="code">test</code> command for <small class="sc">POSIX</small> conformance. |
| </p> |
| </dd> |
| <dt><code class="code"><var class="var">string1</var> != <var class="var">string2</var></code></dt> |
| <dd><p>True if the strings are not equal. |
| </p> |
| </dd> |
| <dt><code class="code"><var class="var">string1</var> < <var class="var">string2</var></code></dt> |
| <dd><p>True if <var class="var">string1</var> sorts before <var class="var">string2</var> lexicographically. |
| </p> |
| </dd> |
| <dt><code class="code"><var class="var">string1</var> > <var class="var">string2</var></code></dt> |
| <dd><p>True if <var class="var">string1</var> sorts after <var class="var">string2</var> lexicographically. |
| </p> |
| </dd> |
| <dt><code class="code"><var class="var">arg1</var> OP <var class="var">arg2</var></code></dt> |
| <dd><p><code class="code">OP</code> is one of |
| ‘<samp class="samp">-eq</samp>’, ‘<samp class="samp">-ne</samp>’, ‘<samp class="samp">-lt</samp>’, ‘<samp class="samp">-le</samp>’, ‘<samp class="samp">-gt</samp>’, or ‘<samp class="samp">-ge</samp>’. |
| These arithmetic binary operators return true if <var class="var">arg1</var> |
| is equal to, not equal to, less than, less than or equal to, |
| greater than, or greater than or equal to <var class="var">arg2</var>, |
| respectively. <var class="var">Arg1</var> and <var class="var">arg2</var> |
| may be positive or negative integers. |
| When used with the <code class="code">[[</code> command, <var class="var">Arg1</var> and <var class="var">Arg2</var> |
| are evaluated as arithmetic expressions (see <a class="pxref" href="#Shell-Arithmetic">Shell Arithmetic</a>). |
| </p></dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Shell-Arithmetic"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Aliases" accesskey="n" rel="next">Aliases</a>, Previous: <a href="#Bash-Conditional-Expressions" accesskey="p" rel="prev">Bash Conditional Expressions</a>, Up: <a href="#Bash-Features" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Shell-Arithmetic-1"><span>6.5 Shell Arithmetic<a class="copiable-link" href="#Shell-Arithmetic-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-arithmetic_002c-shell"></a> |
| <a class="index-entry-id" id="index-shell-arithmetic"></a> |
| <a class="index-entry-id" id="index-expressions_002c-arithmetic"></a> |
| <a class="index-entry-id" id="index-evaluation_002c-arithmetic"></a> |
| <a class="index-entry-id" id="index-arithmetic-evaluation"></a> |
| |
| <p>The shell allows arithmetic expressions to be evaluated, as one of |
| the shell expansions or by using the <code class="code">((</code> compound command, the |
| <code class="code">let</code> builtin, or the <samp class="option">-i</samp> option to the <code class="code">declare</code> builtin. |
| </p> |
| <p>Evaluation is done in fixed-width integers with no check for overflow, |
| though division by 0 is trapped and flagged as an error. |
| The operators and their precedence, associativity, and values |
| are the same as in the C language. |
| The following list of operators is grouped into levels of |
| equal-precedence operators. |
| The levels are listed in order of decreasing precedence. |
| </p> |
| <dl class="table"> |
| <dt><code class="code"><var class="var">id</var>++ <var class="var">id</var>--</code></dt> |
| <dd><p>variable post-increment and post-decrement |
| </p> |
| </dd> |
| <dt><code class="code">++<var class="var">id</var> --<var class="var">id</var></code></dt> |
| <dd><p>variable pre-increment and pre-decrement |
| </p> |
| </dd> |
| <dt><code class="code">- +</code></dt> |
| <dd><p>unary minus and plus |
| </p> |
| </dd> |
| <dt><code class="code">! ~</code></dt> |
| <dd><p>logical and bitwise negation |
| </p> |
| </dd> |
| <dt><code class="code">**</code></dt> |
| <dd><p>exponentiation |
| </p> |
| </dd> |
| <dt><code class="code">* / %</code></dt> |
| <dd><p>multiplication, division, remainder |
| </p> |
| </dd> |
| <dt><code class="code">+ -</code></dt> |
| <dd><p>addition, subtraction |
| </p> |
| </dd> |
| <dt><code class="code"><< >></code></dt> |
| <dd><p>left and right bitwise shifts |
| </p> |
| </dd> |
| <dt><code class="code"><= >= < ></code></dt> |
| <dd><p>comparison |
| </p> |
| </dd> |
| <dt><code class="code">== !=</code></dt> |
| <dd><p>equality and inequality |
| </p> |
| </dd> |
| <dt><code class="code">&</code></dt> |
| <dd><p>bitwise AND |
| </p> |
| </dd> |
| <dt><code class="code">^</code></dt> |
| <dd><p>bitwise exclusive OR |
| </p> |
| </dd> |
| <dt><code class="code">|</code></dt> |
| <dd><p>bitwise OR |
| </p> |
| </dd> |
| <dt><code class="code">&&</code></dt> |
| <dd><p>logical AND |
| </p> |
| </dd> |
| <dt><code class="code">||</code></dt> |
| <dd><p>logical OR |
| </p> |
| </dd> |
| <dt><code class="code">expr ? expr : expr</code></dt> |
| <dd><p>conditional operator |
| </p> |
| </dd> |
| <dt><code class="code">= *= /= %= += -= <<= >>= &= ^= |=</code></dt> |
| <dd><p>assignment |
| </p> |
| </dd> |
| <dt><code class="code">expr1 , expr2</code></dt> |
| <dd><p>comma |
| </p></dd> |
| </dl> |
| |
| <p>Shell variables are allowed as operands; parameter expansion is |
| performed before the expression is evaluated. |
| Within an expression, shell variables may also be referenced by name |
| without using the parameter expansion syntax. |
| A shell variable that is null or unset evaluates to 0 when referenced |
| by name without using the parameter expansion syntax. |
| The value of a variable is evaluated as an arithmetic expression |
| when it is referenced, or when a variable which has been given the |
| <code class="code">integer</code> attribute using ‘<samp class="samp">declare -i</samp>’ is assigned a value. |
| A null value evaluates to 0. |
| A shell variable need not have its <code class="code">integer</code> attribute turned on |
| to be used in an expression. |
| </p> |
| <p>Integer constants follow the C language definition, without suffixes or |
| character constants. |
| Constants with a leading 0 are interpreted as octal numbers. |
| A leading ‘<samp class="samp">0x</samp>’ or ‘<samp class="samp">0X</samp>’ denotes hexadecimal. Otherwise, |
| numbers take the form [<var class="var">base</var><code class="code">#</code>]<var class="var">n</var>, where the optional <var class="var">base</var> |
| is a decimal number between 2 and 64 representing the arithmetic |
| base, and <var class="var">n</var> is a number in that base. |
| If <var class="var">base</var><code class="code">#</code> is omitted, then base 10 is used. |
| When specifying <var class="var">n</var>, |
| if a non-digit is required, |
| the digits greater than 9 are represented by the lowercase letters, |
| the uppercase letters, ‘<samp class="samp">@</samp>’, and ‘<samp class="samp">_</samp>’, in that order. |
| If <var class="var">base</var> is less than or equal to 36, lowercase and uppercase |
| letters may be used interchangeably to represent numbers between 10 |
| and 35. |
| </p> |
| <p>Operators are evaluated in order of precedence. Sub-expressions in |
| parentheses are evaluated first and may override the precedence |
| rules above. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Aliases"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Arrays" accesskey="n" rel="next">Arrays</a>, Previous: <a href="#Shell-Arithmetic" accesskey="p" rel="prev">Shell Arithmetic</a>, Up: <a href="#Bash-Features" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Aliases-1"><span>6.6 Aliases<a class="copiable-link" href="#Aliases-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-alias-expansion"></a> |
| |
| <p><em class="dfn">Aliases</em> allow a string to be substituted for a word when it is used |
| as the first word of a simple command. |
| The shell maintains a list of aliases that may be set and unset with |
| the <code class="code">alias</code> and <code class="code">unalias</code> builtin commands. |
| </p> |
| <p>The first word of each simple command, if unquoted, is checked to see |
| if it has an alias. |
| If so, that word is replaced by the text of the alias. |
| The characters ‘<samp class="samp">/</samp>’, ‘<samp class="samp">$</samp>’, ‘<samp class="samp">`</samp>’, ‘<samp class="samp">=</samp>’ and any of the |
| shell metacharacters or quoting characters listed above may not appear |
| in an alias name. |
| The replacement text may contain any valid |
| shell input, including shell metacharacters. |
| The first word of the replacement text is tested for |
| aliases, but a word that is identical to an alias being expanded |
| is not expanded a second time. |
| This means that one may alias <code class="code">ls</code> to <code class="code">"ls -F"</code>, |
| for instance, and Bash does not try to recursively expand the |
| replacement text. |
| If the last character of the alias value is a |
| <code class="code">blank</code>, then the next command word following the |
| alias is also checked for alias expansion. |
| </p> |
| <p>Aliases are created and listed with the <code class="code">alias</code> |
| command, and removed with the <code class="code">unalias</code> command. |
| </p> |
| <p>There is no mechanism for using arguments in the replacement text, |
| as in <code class="code">csh</code>. |
| If arguments are needed, use a shell function |
| (see <a class="pxref" href="#Shell-Functions">Shell Functions</a>). |
| </p> |
| <p>Aliases are not expanded when the shell is not interactive, |
| unless the <code class="code">expand_aliases</code> shell option is set using |
| <code class="code">shopt</code> (see <a class="pxref" href="#The-Shopt-Builtin">The Shopt Builtin</a>). |
| </p> |
| <p>The rules concerning the definition and use of aliases are |
| somewhat confusing. Bash |
| always reads at least one complete line of input, |
| and all lines that make up a compound command, |
| before executing any of the commands on that line or the compound command. |
| Aliases are expanded when a |
| command is read, not when it is executed. Therefore, an |
| alias definition appearing on the same line as another |
| command does not take effect until the next line of input is read. |
| The commands following the alias definition |
| on that line are not affected by the new alias. |
| This behavior is also an issue when functions are executed. |
| Aliases are expanded when a function definition is read, |
| not when the function is executed, because a function definition |
| is itself a command. As a consequence, aliases |
| defined in a function are not available until after that |
| function is executed. To be safe, always put |
| alias definitions on a separate line, and do not use <code class="code">alias</code> |
| in compound commands. |
| </p> |
| <p>For almost every purpose, shell functions are preferred over aliases. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Arrays"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#The-Directory-Stack" accesskey="n" rel="next">The Directory Stack</a>, Previous: <a href="#Aliases" accesskey="p" rel="prev">Aliases</a>, Up: <a href="#Bash-Features" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Arrays-1"><span>6.7 Arrays<a class="copiable-link" href="#Arrays-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-arrays"></a> |
| |
| <p>Bash provides one-dimensional indexed and associative array variables. |
| Any variable may be used as an indexed array; |
| the <code class="code">declare</code> builtin will explicitly declare an array. |
| There is no maximum |
| limit on the size of an array, nor any requirement that members |
| be indexed or assigned contiguously. |
| Indexed arrays are referenced using integers (including arithmetic |
| expressions (see <a class="pxref" href="#Shell-Arithmetic">Shell Arithmetic</a>)) and are zero-based; |
| associative arrays use arbitrary strings. |
| Unless otherwise noted, indexed array indices must be non-negative integers. |
| </p> |
| <p>An indexed array is created automatically if any variable is assigned to |
| using the syntax |
| </p><div class="example"> |
| <pre class="example-preformatted"><var class="var">name</var>[<var class="var">subscript</var>]=<var class="var">value</var> |
| </pre></div> |
| |
| <p>The <var class="var">subscript</var> |
| is treated as an arithmetic expression that must evaluate to a number. |
| To explicitly declare an array, use |
| </p><div class="example"> |
| <pre class="example-preformatted">declare -a <var class="var">name</var> |
| </pre></div> |
| <p>The syntax |
| </p><div class="example"> |
| <pre class="example-preformatted">declare -a <var class="var">name</var>[<var class="var">subscript</var>] |
| </pre></div> |
| <p>is also accepted; the <var class="var">subscript</var> is ignored. |
| </p> |
| <p>Associative arrays are created using |
| </p><div class="example"> |
| <pre class="example-preformatted">declare -A <var class="var">name</var> |
| </pre></div> |
| |
| <p>Attributes may be |
| specified for an array variable using the <code class="code">declare</code> and |
| <code class="code">readonly</code> builtins. Each attribute applies to all members of |
| an array. |
| </p> |
| <p>Arrays are assigned to using compound assignments of the form |
| </p><div class="example"> |
| <pre class="example-preformatted"><var class="var">name</var>=(<var class="var">value1</var> <var class="var">value2</var> ... ) |
| </pre></div> |
| <p>where each |
| <var class="var">value</var> may be of the form <code class="code">[<var class="var">subscript</var>]=</code><var class="var">string</var>. |
| Indexed array assignments do not require anything but <var class="var">string</var>. |
| When assigning to indexed arrays, if |
| the optional subscript is supplied, that index is assigned to; |
| otherwise the index of the element assigned is the last index assigned |
| to by the statement plus one. Indexing starts at zero. |
| </p> |
| <p>Each <var class="var">value</var> in the list undergoes all the shell expansions |
| described above (see <a class="pxref" href="#Shell-Expansions">Shell Expansions</a>). |
| </p> |
| <p>When assigning to an associative array, the words in a compound assignment |
| may be either assignment statements, for which the subscript is required, |
| or a list of words that is interpreted as a sequence of alternating keys |
| and values: |
| <var class="var">name</var>=(<var class="var">key1</var> <var class="var">value1</var> <var class="var">key2</var> <var class="var">value2</var> … ). |
| These are treated identically to |
| <var class="var">name</var>=( [<var class="var">key1</var>]=<var class="var">value1</var> [<var class="var">key2</var>]=<var class="var">value2</var> … ). |
| The first word in the list determines how the remaining words |
| are interpreted; all assignments in a list must be of the same type. |
| When using key/value pairs, the keys may not be missing or empty; |
| a final missing value is treated like the empty string. |
| </p> |
| <p>This syntax is also accepted by the <code class="code">declare</code> |
| builtin. Individual array elements may be assigned to using the |
| <code class="code"><var class="var">name</var>[<var class="var">subscript</var>]=<var class="var">value</var></code> syntax introduced above. |
| </p> |
| <p>When assigning to an indexed array, if <var class="var">name</var> |
| is subscripted by a negative number, that number is |
| interpreted as relative to one greater than the maximum index of |
| <var class="var">name</var>, so negative indices count back from the end of the |
| array, and an index of -1 references the last element. |
| </p> |
| <p>The ‘<samp class="samp">+=</samp>’ operator will append to an array variable when assigning |
| using the compound assignment syntax; see <a class="ref" href="#Shell-Parameters">Shell Parameters</a> above. |
| </p> |
| <p>Any element of an array may be referenced using |
| <code class="code">${<var class="var">name</var>[<var class="var">subscript</var>]}</code>. |
| The braces are required to avoid |
| conflicts with the shell’s filename expansion operators. If the |
| <var class="var">subscript</var> is ‘<samp class="samp">@</samp>’ or ‘<samp class="samp">*</samp>’, the word expands to all members |
| of the array <var class="var">name</var>. These subscripts differ only when the word |
| appears within double quotes. |
| If the word is double-quoted, |
| <code class="code">${<var class="var">name</var>[*]}</code> expands to a single word with |
| the value of each array member separated by the first character of the |
| <code class="env">IFS</code> variable, and <code class="code">${<var class="var">name</var>[@]}</code> expands each element of |
| <var class="var">name</var> to a separate word. When there are no array members, |
| <code class="code">${<var class="var">name</var>[@]}</code> expands to nothing. |
| If the double-quoted expansion occurs within a word, the expansion of |
| the first parameter is joined with the beginning part of the original |
| word, and the expansion of the last parameter is joined with the last |
| part of the original word. |
| This is analogous to the |
| expansion of the special parameters ‘<samp class="samp">@</samp>’ and ‘<samp class="samp">*</samp>’. |
| <code class="code">${#<var class="var">name</var>[<var class="var">subscript</var>]}</code> expands to the length of |
| <code class="code">${<var class="var">name</var>[<var class="var">subscript</var>]}</code>. |
| If <var class="var">subscript</var> is ‘<samp class="samp">@</samp>’ or |
| ‘<samp class="samp">*</samp>’, the expansion is the number of elements in the array. |
| If the <var class="var">subscript</var> |
| used to reference an element of an indexed array |
| evaluates to a number less than zero, it is |
| interpreted as relative to one greater than the maximum index of the array, |
| so negative indices count back from the end of the array, |
| and an index of -1 refers to the last element. |
| </p> |
| <p>Referencing an array variable without a subscript is equivalent to |
| referencing with a subscript of 0. |
| Any reference to a variable using a valid subscript is legal, and |
| <code class="code">bash</code> will create an array if necessary. |
| </p> |
| <p>An array variable is considered set if a subscript has been assigned a |
| value. The null string is a valid value. |
| </p> |
| <p>It is possible to obtain the keys (indices) of an array as well as the values. |
| ${!<var class="var">name</var>[@]} and ${!<var class="var">name</var>[*]} expand to the indices |
| assigned in array variable <var class="var">name</var>. |
| The treatment when in double quotes is similar to the expansion of the |
| special parameters ‘<samp class="samp">@</samp>’ and ‘<samp class="samp">*</samp>’ within double quotes. |
| </p> |
| <p>The <code class="code">unset</code> builtin is used to destroy arrays. |
| <code class="code">unset <var class="var">name</var>[<var class="var">subscript</var>]</code> |
| destroys the array element at index <var class="var">subscript</var>. |
| Negative subscripts to indexed arrays are interpreted as described above. |
| Unsetting the last element of an array variable does not unset the variable. |
| <code class="code">unset <var class="var">name</var></code>, where <var class="var">name</var> is an array, removes the |
| entire array. |
| <code class="code">unset <var class="var">name</var>[<var class="var">subscript</var>]</code> behaves differently |
| depending on the array type when given a |
| subscript of ‘<samp class="samp">*</samp>’ or ‘<samp class="samp">@</samp>’. |
| When <var class="var">name</var> is an associative array, it removes the element with key |
| ‘<samp class="samp">*</samp>’ or ‘<samp class="samp">@</samp>’. |
| If <var class="var">name</var> is an indexed array, <code class="code">unset</code> removes all of the elements, |
| but does not remove the array itself. |
| </p> |
| <p>When using a variable name with a subscript as an argument to a command, |
| such as with <code class="code">unset</code>, without using the word expansion syntax |
| described above, the argument is subject to the shell’s filename expansion. |
| If filename expansion is not desired, the argument should be quoted. |
| </p> |
| <p>The <code class="code">declare</code>, <code class="code">local</code>, and <code class="code">readonly</code> |
| builtins each accept a <samp class="option">-a</samp> option to specify an indexed |
| array and a <samp class="option">-A</samp> option to specify an associative array. |
| If both options are supplied, <samp class="option">-A</samp> takes precedence. |
| The <code class="code">read</code> builtin accepts a <samp class="option">-a</samp> |
| option to assign a list of words read from the standard input |
| to an array, and can read values from the standard input into |
| individual array elements. The <code class="code">set</code> and <code class="code">declare</code> |
| builtins display array values in a way that allows them to be |
| reused as input. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="The-Directory-Stack"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Controlling-the-Prompt" accesskey="n" rel="next">Controlling the Prompt</a>, Previous: <a href="#Arrays" accesskey="p" rel="prev">Arrays</a>, Up: <a href="#Bash-Features" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="The-Directory-Stack-1"><span>6.8 The Directory Stack<a class="copiable-link" href="#The-Directory-Stack-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-directory-stack"></a> |
| |
| |
| <p>The directory stack is a list of recently-visited directories. The |
| <code class="code">pushd</code> builtin adds directories to the stack as it changes |
| the current directory, and the <code class="code">popd</code> builtin removes specified |
| directories from the stack and changes the current directory to |
| the directory removed. The <code class="code">dirs</code> builtin displays the contents |
| of the directory stack. The current directory is always the "top" |
| of the directory stack. |
| </p> |
| <p>The contents of the directory stack are also visible |
| as the value of the <code class="env">DIRSTACK</code> shell variable. |
| </p> |
| <ul class="mini-toc"> |
| <li><a href="#Directory-Stack-Builtins" accesskey="1">Directory Stack Builtins</a></li> |
| </ul> |
| <hr> |
| <div class="subsection-level-extent" id="Directory-Stack-Builtins"> |
| <div class="nav-panel"> |
| <p> |
| Up: <a href="#The-Directory-Stack" accesskey="u" rel="up">The Directory Stack</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Directory-Stack-Builtins-1"><span>6.8.1 Directory Stack Builtins<a class="copiable-link" href="#Directory-Stack-Builtins-1"> ¶</a></span></h4> |
| |
| <dl class="table"> |
| <dt><a id="index-dirs"></a><span><code class="code">dirs</code><a class="copiable-link" href="#index-dirs"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">dirs [-clpv] [+<var class="var">N</var> | -<var class="var">N</var>] |
| </pre></div> |
| |
| <p>Display the list of currently remembered directories. Directories |
| are added to the list with the <code class="code">pushd</code> command; the |
| <code class="code">popd</code> command removes directories from the list. |
| The current directory is always the first directory in the stack. |
| </p> |
| <dl class="table"> |
| <dt><code class="code">-c</code></dt> |
| <dd><p>Clears the directory stack by deleting all of the elements. |
| </p></dd> |
| <dt><code class="code">-l</code></dt> |
| <dd><p>Produces a listing using full pathnames; |
| the default listing format uses a tilde to denote the home directory. |
| </p></dd> |
| <dt><code class="code">-p</code></dt> |
| <dd><p>Causes <code class="code">dirs</code> to print the directory stack with one entry per |
| line. |
| </p></dd> |
| <dt><code class="code">-v</code></dt> |
| <dd><p>Causes <code class="code">dirs</code> to print the directory stack with one entry per |
| line, prefixing each entry with its index in the stack. |
| </p></dd> |
| <dt><code class="code">+<var class="var">N</var></code></dt> |
| <dd><p>Displays the <var class="var">N</var>th directory (counting from the left of the |
| list printed by <code class="code">dirs</code> when invoked without options), starting |
| with zero. |
| </p></dd> |
| <dt><code class="code">-<var class="var">N</var></code></dt> |
| <dd><p>Displays the <var class="var">N</var>th directory (counting from the right of the |
| list printed by <code class="code">dirs</code> when invoked without options), starting |
| with zero. |
| </p></dd> |
| </dl> |
| |
| </dd> |
| <dt><a id="index-popd"></a><span><code class="code">popd</code><a class="copiable-link" href="#index-popd"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">popd [-n] [+<var class="var">N</var> | -<var class="var">N</var>] |
| </pre></div> |
| |
| <p>Removes elements from the directory stack. |
| The elements are numbered from 0 starting at the first directory |
| listed by <code class="code">dirs</code>; |
| that is, <code class="code">popd</code> is equivalent to <code class="code">popd +0</code>. |
| </p> |
| <p>When no arguments are given, <code class="code">popd</code> |
| removes the top directory from the stack and changes to |
| the new top directory. |
| </p> |
| <p>Arguments, if supplied, have the following meanings: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">-n</code></dt> |
| <dd><p>Suppresses the normal change of directory when removing directories |
| from the stack, so that only the stack is manipulated. |
| </p></dd> |
| <dt><code class="code">+<var class="var">N</var></code></dt> |
| <dd><p>Removes the <var class="var">N</var>th directory (counting from the left of the |
| list printed by <code class="code">dirs</code>), starting with zero, from the stack. |
| </p></dd> |
| <dt><code class="code">-<var class="var">N</var></code></dt> |
| <dd><p>Removes the <var class="var">N</var>th directory (counting from the right of the |
| list printed by <code class="code">dirs</code>), starting with zero, from the stack. |
| </p></dd> |
| </dl> |
| |
| <p>If the top element of the directory stack is modified, and |
| the <samp class="option">-n</samp> option was not supplied, <code class="code">popd</code> uses the <code class="code">cd</code> |
| builtin to change to the directory at the top of the stack. |
| If the <code class="code">cd</code> fails, <code class="code">popd</code> returns a non-zero value. |
| </p> |
| <p>Otherwise, <code class="code">popd</code> returns an unsuccessful status if |
| an invalid option is encountered, the directory stack |
| is empty, or a non-existent directory stack entry is specified. |
| </p> |
| <p>If the <code class="code">popd</code> command is successful, |
| Bash runs <code class="code">dirs</code> to show the final contents of the directory stack, |
| and the return status is 0. |
| </p> |
| </dd> |
| <dt><a id="index-pushd"></a><span><code class="code">pushd</code><a class="copiable-link" href="#index-pushd"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">pushd [-n] [<var class="var">+N</var> | <var class="var">-N</var> | <var class="var">dir</var>] |
| </pre></div> |
| |
| <p>Adds a directory to the top of the directory stack, or rotates |
| the stack, making the new top of the stack the current working |
| directory. |
| With no arguments, <code class="code">pushd</code> exchanges the top two elements |
| of the directory stack. |
| </p> |
| <p>Arguments, if supplied, have the following meanings: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">-n</code></dt> |
| <dd><p>Suppresses the normal change of directory when rotating or |
| adding directories to the stack, so that only the stack is manipulated. |
| </p></dd> |
| <dt><code class="code">+<var class="var">N</var></code></dt> |
| <dd><p>Brings the <var class="var">N</var>th directory (counting from the left of the |
| list printed by <code class="code">dirs</code>, starting with zero) to the top of |
| the list by rotating the stack. |
| </p></dd> |
| <dt><code class="code">-<var class="var">N</var></code></dt> |
| <dd><p>Brings the <var class="var">N</var>th directory (counting from the right of the |
| list printed by <code class="code">dirs</code>, starting with zero) to the top of |
| the list by rotating the stack. |
| </p></dd> |
| <dt><code class="code"><var class="var">dir</var></code></dt> |
| <dd><p>Makes <var class="var">dir</var> be the top of the stack. |
| </p></dd> |
| </dl> |
| |
| <p>After the stack has been modified, if the <samp class="option">-n</samp> option was not |
| supplied, <code class="code">pushd</code> uses the <code class="code">cd</code> builtin to change to the |
| directory at the top of the stack. |
| If the <code class="code">cd</code> fails, <code class="code">pushd</code> returns a non-zero value. |
| </p> |
| <p>Otherwise, if no arguments are supplied, <code class="code">pushd</code> returns 0 unless the |
| directory stack is empty. |
| When rotating the directory stack, <code class="code">pushd</code> returns 0 unless |
| the directory stack is empty or a non-existent directory stack element |
| is specified. |
| </p> |
| <p>If the <code class="code">pushd</code> command is successful, |
| Bash runs <code class="code">dirs</code> to show the final contents of the directory stack. |
| </p> |
| </dd> |
| </dl> |
| |
| <hr> |
| </div> |
| </div> |
| <div class="section-level-extent" id="Controlling-the-Prompt"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#The-Restricted-Shell" accesskey="n" rel="next">The Restricted Shell</a>, Previous: <a href="#The-Directory-Stack" accesskey="p" rel="prev">The Directory Stack</a>, Up: <a href="#Bash-Features" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Controlling-the-Prompt-1"><span>6.9 Controlling the Prompt<a class="copiable-link" href="#Controlling-the-Prompt-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-prompting"></a> |
| |
| <p>Bash examines the value of the array variable <code class="env">PROMPT_COMMAND</code> just before |
| printing each primary prompt. |
| If any elements in <code class="env">PROMPT_COMMAND</code> are set and non-null, Bash |
| executes each value, in numeric order, |
| just as if it had been typed on the command line. |
| </p> |
| <p>In addition, the following table describes the special characters which |
| can appear in the prompt variables <code class="env">PS0</code>, <code class="env">PS1</code>, <code class="env">PS2</code>, and |
| <code class="env">PS4</code>: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">\a</code></dt> |
| <dd><p>A bell character. |
| </p></dd> |
| <dt><code class="code">\d</code></dt> |
| <dd><p>The date, in "Weekday Month Date" format (e.g., "Tue May 26"). |
| </p></dd> |
| <dt><code class="code">\D{<var class="var">format</var>}</code></dt> |
| <dd><p>The <var class="var">format</var> is passed to <code class="code">strftime</code>(3) and the result is inserted |
| into the prompt string; an empty <var class="var">format</var> results in a locale-specific |
| time representation. The braces are required. |
| </p></dd> |
| <dt><code class="code">\e</code></dt> |
| <dd><p>An escape character. |
| </p></dd> |
| <dt><code class="code">\h</code></dt> |
| <dd><p>The hostname, up to the first ‘.’. |
| </p></dd> |
| <dt><code class="code">\H</code></dt> |
| <dd><p>The hostname. |
| </p></dd> |
| <dt><code class="code">\j</code></dt> |
| <dd><p>The number of jobs currently managed by the shell. |
| </p></dd> |
| <dt><code class="code">\l</code></dt> |
| <dd><p>The basename of the shell’s terminal device name. |
| </p></dd> |
| <dt><code class="code">\n</code></dt> |
| <dd><p>A newline. |
| </p></dd> |
| <dt><code class="code">\r</code></dt> |
| <dd><p>A carriage return. |
| </p></dd> |
| <dt><code class="code">\s</code></dt> |
| <dd><p>The name of the shell, the basename of <code class="code">$0</code> (the portion |
| following the final slash). |
| </p></dd> |
| <dt><code class="code">\t</code></dt> |
| <dd><p>The time, in 24-hour HH:MM:SS format. |
| </p></dd> |
| <dt><code class="code">\T</code></dt> |
| <dd><p>The time, in 12-hour HH:MM:SS format. |
| </p></dd> |
| <dt><code class="code">\@</code></dt> |
| <dd><p>The time, in 12-hour am/pm format. |
| </p></dd> |
| <dt><code class="code">\A</code></dt> |
| <dd><p>The time, in 24-hour HH:MM format. |
| </p></dd> |
| <dt><code class="code">\u</code></dt> |
| <dd><p>The username of the current user. |
| </p></dd> |
| <dt><code class="code">\v</code></dt> |
| <dd><p>The version of Bash (e.g., 2.00) |
| </p></dd> |
| <dt><code class="code">\V</code></dt> |
| <dd><p>The release of Bash, version + patchlevel (e.g., 2.00.0) |
| </p></dd> |
| <dt><code class="code">\w</code></dt> |
| <dd><p>The value of the <code class="code">PWD</code> shell variable (<code class="env">$PWD</code>), |
| with <code class="env">$HOME</code> abbreviated with a tilde |
| (uses the <code class="env">$PROMPT_DIRTRIM</code> variable). |
| </p></dd> |
| <dt><code class="code">\W</code></dt> |
| <dd><p>The basename of <code class="env">$PWD</code>, with <code class="env">$HOME</code> abbreviated with a tilde. |
| </p></dd> |
| <dt><code class="code">\!</code></dt> |
| <dd><p>The history number of this command. |
| </p></dd> |
| <dt><code class="code">\#</code></dt> |
| <dd><p>The command number of this command. |
| </p></dd> |
| <dt><code class="code">\$</code></dt> |
| <dd><p>If the effective uid is 0, <code class="code">#</code>, otherwise <code class="code">$</code>. |
| </p></dd> |
| <dt><code class="code">\<var class="var">nnn</var></code></dt> |
| <dd><p>The character whose ASCII code is the octal value <var class="var">nnn</var>. |
| </p></dd> |
| <dt><code class="code">\\</code></dt> |
| <dd><p>A backslash. |
| </p></dd> |
| <dt><code class="code">\[</code></dt> |
| <dd><p>Begin a sequence of non-printing characters. This could be used to |
| embed a terminal control sequence into the prompt. |
| </p></dd> |
| <dt><code class="code">\]</code></dt> |
| <dd><p>End a sequence of non-printing characters. |
| </p></dd> |
| </dl> |
| |
| <p>The command number and the history number are usually different: |
| the history number of a command is its position in the history |
| list, which may include commands restored from the history file |
| (see <a class="pxref" href="#Bash-History-Facilities">Bash History Facilities</a>), while the command number is |
| the position in the sequence of commands executed during the current |
| shell session. |
| </p> |
| <p>After the string is decoded, it is expanded via |
| parameter expansion, command substitution, arithmetic |
| expansion, and quote removal, subject to the value of the |
| <code class="code">promptvars</code> shell option (see <a class="pxref" href="#The-Shopt-Builtin">The Shopt Builtin</a>). |
| This can have unwanted side effects if escaped portions of the string |
| appear within command substitution or contain characters special to |
| word expansion. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="The-Restricted-Shell"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Bash-POSIX-Mode" accesskey="n" rel="next">Bash POSIX Mode</a>, Previous: <a href="#Controlling-the-Prompt" accesskey="p" rel="prev">Controlling the Prompt</a>, Up: <a href="#Bash-Features" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="The-Restricted-Shell-1"><span>6.10 The Restricted Shell<a class="copiable-link" href="#The-Restricted-Shell-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-restricted-shell"></a> |
| |
| <p>If Bash is started with the name <code class="code">rbash</code>, or the |
| <samp class="option">--restricted</samp> |
| or |
| <samp class="option">-r</samp> |
| option is supplied at invocation, the shell becomes restricted. |
| A restricted shell is used to |
| set up an environment more controlled than the standard shell. |
| A restricted shell behaves identically to <code class="code">bash</code> |
| with the exception that the following are disallowed or not performed: |
| </p> |
| <ul class="itemize mark-bullet"> |
| <li>Changing directories with the <code class="code">cd</code> builtin. |
| </li><li>Setting or unsetting the values of the <code class="env">SHELL</code>, <code class="env">PATH</code>, |
| <code class="env">HISTFILE</code>, |
| <code class="env">ENV</code>, or <code class="env">BASH_ENV</code> variables. |
| </li><li>Specifying command names containing slashes. |
| </li><li>Specifying a filename containing a slash as an argument to the <code class="code">.</code> |
| builtin command. |
| </li><li>Specifying a filename containing a slash as an argument to the <code class="code">history</code> |
| builtin command. |
| </li><li>Specifying a filename containing a slash as an argument to the <samp class="option">-p</samp> |
| option to the <code class="code">hash</code> builtin command. |
| </li><li>Importing function definitions from the shell environment at startup. |
| </li><li>Parsing the value of <code class="env">SHELLOPTS</code> from the shell environment at startup. |
| </li><li>Redirecting output using the ‘<samp class="samp">></samp>’, ‘<samp class="samp">>|</samp>’, ‘<samp class="samp"><></samp>’, ‘<samp class="samp">>&</samp>’, |
| ‘<samp class="samp">&></samp>’, and ‘<samp class="samp">>></samp>’ redirection operators. |
| </li><li>Using the <code class="code">exec</code> builtin to replace the shell with another command. |
| </li><li>Adding or deleting builtin commands with the |
| <samp class="option">-f</samp> and <samp class="option">-d</samp> options to the <code class="code">enable</code> builtin. |
| </li><li>Using the <code class="code">enable</code> builtin command to enable disabled shell builtins. |
| </li><li>Specifying the <samp class="option">-p</samp> option to the <code class="code">command</code> builtin. |
| </li><li>Turning off restricted mode with ‘<samp class="samp">set +r</samp>’ or ‘<samp class="samp">shopt -u restricted_shell</samp>’. |
| </li></ul> |
| |
| <p>These restrictions are enforced after any startup files are read. |
| </p> |
| <p>When a command that is found to be a shell script is executed |
| (see <a class="pxref" href="#Shell-Scripts">Shell Scripts</a>), <code class="code">rbash</code> turns off any restrictions in |
| the shell spawned to execute the script. |
| </p> |
| <p>The restricted shell mode is only one component of a useful restricted |
| environment. It should be accompanied by setting <code class="env">PATH</code> to a value |
| that allows execution of only a few verified commands (commands that |
| allow shell escapes are particularly vulnerable), changing the current |
| directory to a non-writable directory other than <code class="env">$HOME</code> after login, |
| not allowing the restricted shell to execute shell scripts, and cleaning |
| the environment of variables that cause some commands to modify their |
| behavior (e.g., <code class="env">VISUAL</code> or <code class="env">PAGER</code>). |
| </p> |
| <p>Modern systems provide more secure ways to implement a restricted environment, |
| such as <code class="code">jails</code>, <code class="code">zones</code>, or <code class="code">containers</code>. |
| </p> |
| |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Bash-POSIX-Mode"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Shell-Compatibility-Mode" accesskey="n" rel="next">Shell Compatibility Mode</a>, Previous: <a href="#The-Restricted-Shell" accesskey="p" rel="prev">The Restricted Shell</a>, Up: <a href="#Bash-Features" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Bash-POSIX-Mode-1"><span>6.11 Bash POSIX Mode<a class="copiable-link" href="#Bash-POSIX-Mode-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-POSIX-Mode"></a> |
| |
| <p>Starting Bash with the <samp class="option">--posix</samp> command-line option or executing |
| ‘<samp class="samp">set -o posix</samp>’ while Bash is running will cause Bash to conform more |
| closely to the <small class="sc">POSIX</small> standard by changing the behavior to |
| match that specified by <small class="sc">POSIX</small> in areas where the Bash default differs. |
| </p> |
| <p>When invoked as <code class="code">sh</code>, Bash enters <small class="sc">POSIX</small> mode after reading the |
| startup files. |
| </p> |
| <p>The following list is what’s changed when ‘<small class="sc">POSIX</small> mode’ is in effect: |
| </p> |
| <ol class="enumerate"> |
| <li> Bash ensures that the <code class="env">POSIXLY_CORRECT</code> variable is set. |
| |
| </li><li> When a command in the hash table no longer exists, Bash will re-search |
| <code class="env">$PATH</code> to find the new location. This is also available with |
| ‘<samp class="samp">shopt -s checkhash</samp>’. |
| |
| </li><li> Bash will not insert a command without the execute bit set into the |
| command hash table, even if it returns it as a (last-ditch) result |
| from a <code class="env">$PATH</code> search. |
| |
| </li><li> The message printed by the job control code and builtins when a job |
| exits with a non-zero status is ‘Done(status)’. |
| |
| </li><li> The message printed by the job control code and builtins when a job |
| is stopped is ‘Stopped(<var class="var">signame</var>)’, where <var class="var">signame</var> is, for |
| example, <code class="code">SIGTSTP</code>. |
| |
| </li><li> Alias expansion is always enabled, even in non-interactive shells. |
| |
| </li><li> Reserved words appearing in a context where reserved words are recognized |
| do not undergo alias expansion. |
| |
| </li><li> Alias expansion is performed when initially parsing a command substitution. |
| The default mode generally defers it, when enabled, until the command |
| substitution is executed. This means that command substitution will not |
| expand aliases that are defined after the command substitution is initially |
| parsed (e.g., as part of a function definition). |
| |
| </li><li> The <small class="sc">POSIX</small> <code class="env">PS1</code> and <code class="env">PS2</code> expansions of ‘<samp class="samp">!</samp>’ to |
| the history number and ‘<samp class="samp">!!</samp>’ to ‘<samp class="samp">!</samp>’ are enabled, |
| and parameter expansion is performed on the values of <code class="env">PS1</code> and |
| <code class="env">PS2</code> regardless of the setting of the <code class="code">promptvars</code> option. |
| |
| </li><li> The <small class="sc">POSIX</small> startup files are executed (<code class="env">$ENV</code>) rather than |
| the normal Bash files. |
| |
| </li><li> Tilde expansion is only performed on assignments preceding a command |
| name, rather than on all assignment statements on the line. |
| |
| </li><li> The default history file is <samp class="file">~/.sh_history</samp> (this is the |
| default value of <code class="env">$HISTFILE</code>). |
| |
| </li><li> Redirection operators do not perform filename expansion on the word |
| in the redirection unless the shell is interactive. |
| |
| </li><li> Redirection operators do not perform word splitting on the word in the |
| redirection. |
| |
| </li><li> Function names must be valid shell <code class="code">name</code>s. That is, they may not |
| contain characters other than letters, digits, and underscores, and |
| may not start with a digit. Declaring a function with an invalid name |
| causes a fatal syntax error in non-interactive shells. |
| |
| </li><li> Function names may not be the same as one of the <small class="sc">POSIX</small> special |
| builtins. |
| |
| </li><li> <small class="sc">POSIX</small> special builtins are found before shell functions |
| during command lookup. |
| |
| </li><li> When printing shell function definitions (e.g., by <code class="code">type</code>), Bash does |
| not print the <code class="code">function</code> keyword. |
| |
| </li><li> Literal tildes that appear as the first character in elements of |
| the <code class="env">PATH</code> variable are not expanded as described above |
| under <a class="ref" href="#Tilde-Expansion">Tilde Expansion</a>. |
| |
| </li><li> The <code class="code">time</code> reserved word may be used by itself as a command. When |
| used in this way, it displays timing statistics for the shell and its |
| completed children. The <code class="env">TIMEFORMAT</code> variable controls the format |
| of the timing information. |
| |
| </li><li> When parsing and expanding a ${…} expansion that appears within |
| double quotes, single quotes are no longer special and cannot be used to |
| quote a closing brace or other special character, unless the operator is |
| one of those defined to perform pattern removal. In this case, they do |
| not have to appear as matched pairs. |
| |
| </li><li> The parser does not recognize <code class="code">time</code> as a reserved word if the next |
| token begins with a ‘<samp class="samp">-</samp>’. |
| |
| |
| </li><li> The ‘<samp class="samp">!</samp>’ character does not introduce history expansion within a |
| double-quoted string, even if the <code class="code">histexpand</code> option is enabled. |
| |
| </li><li> If a <small class="sc">POSIX</small> special builtin returns an error status, a |
| non-interactive shell exits. The fatal errors are those listed in |
| the <small class="sc">POSIX</small> standard, and include things like passing incorrect options, |
| redirection errors, variable assignment errors for assignments preceding |
| the command name, and so on. |
| |
| </li><li> A non-interactive shell exits with an error status if a variable |
| assignment error occurs when no command name follows the assignment |
| statements. |
| A variable assignment error occurs, for example, when trying to assign |
| a value to a readonly variable. |
| |
| </li><li> A non-interactive shell exits with an error status if a variable |
| assignment error occurs in an assignment statement preceding a special |
| builtin, but not with any other simple command. For any other simple |
| command, the shell aborts execution of that command, and execution continues |
| at the top level ("the shell shall not perform any further processing of the |
| command in which the error occurred"). |
| |
| </li><li> A non-interactive shell exits with an error status if the iteration |
| variable in a <code class="code">for</code> statement or the selection variable in a |
| <code class="code">select</code> statement is a readonly variable. |
| |
| </li><li> Non-interactive shells exit if <var class="var">filename</var> in <code class="code">.</code> <var class="var">filename</var> |
| is not found. |
| |
| </li><li> Non-interactive shells exit if a syntax error in an arithmetic expansion |
| results in an invalid expression. |
| |
| </li><li> Non-interactive shells exit if a parameter expansion error occurs. |
| |
| </li><li> Non-interactive shells exit if there is a syntax error in a script read |
| with the <code class="code">.</code> or <code class="code">source</code> builtins, or in a string processed by |
| the <code class="code">eval</code> builtin. |
| |
| </li><li> While variable indirection is available, it may not be applied to the |
| ‘<samp class="samp">#</samp>’ and ‘<samp class="samp">?</samp>’ special parameters. |
| |
| </li><li> Expanding the ‘<samp class="samp">*</samp>’ special parameter in a pattern context where the |
| expansion is double-quoted does not treat the <code class="code">$*</code> as if it were |
| double-quoted. |
| |
| </li><li> Assignment statements preceding <small class="sc">POSIX</small> special builtins |
| persist in the shell environment after the builtin completes. |
| |
| </li><li> The <code class="code">command</code> builtin does not prevent builtins that take assignment |
| statements as arguments from expanding them as assignment statements; |
| when not in <small class="sc">POSIX</small> mode, assignment builtins lose their assignment |
| statement expansion properties when preceded by <code class="code">command</code>. |
| |
| </li><li> The <code class="code">bg</code> builtin uses the required format to describe each job placed |
| in the background, which does not include an indication of whether the job |
| is the current or previous job. |
| |
| </li><li> The output of ‘<samp class="samp">kill -l</samp>’ prints all the signal names on a single line, |
| separated by spaces, without the ‘<samp class="samp">SIG</samp>’ prefix. |
| |
| </li><li> The <code class="code">kill</code> builtin does not accept signal names with a ‘<samp class="samp">SIG</samp>’ |
| prefix. |
| |
| </li><li> The <code class="code">export</code> and <code class="code">readonly</code> builtin commands display their |
| output in the format required by <small class="sc">POSIX</small>. |
| |
| </li><li> The <code class="code">trap</code> builtin displays signal names without the leading |
| <code class="code">SIG</code>. |
| |
| </li><li> The <code class="code">trap</code> builtin doesn’t check the first argument for a possible |
| signal specification and revert the signal handling to the original |
| disposition if it is, unless that argument consists solely of digits and |
| is a valid signal number. If users want to reset the handler for a given |
| signal to the original disposition, they should use ‘<samp class="samp">-</samp>’ as the |
| first argument. |
| |
| </li><li> <code class="code">trap -p</code> displays signals whose dispositions are set to SIG_DFL and |
| those that were ignored when the shell started. |
| |
| </li><li> The <code class="code">.</code> and <code class="code">source</code> builtins do not search the current directory |
| for the filename argument if it is not found by searching <code class="env">PATH</code>. |
| |
| </li><li> Enabling <small class="sc">POSIX</small> mode has the effect of setting the |
| <code class="code">inherit_errexit</code> option, so |
| subshells spawned to execute command substitutions inherit the value of |
| the <samp class="option">-e</samp> option from the parent shell. |
| When the <code class="code">inherit_errexit</code> option is not enabled, |
| Bash clears the <samp class="option">-e</samp> option in such subshells. |
| |
| </li><li> Enabling <small class="sc">POSIX</small> mode has the effect of setting the |
| <code class="code">shift_verbose</code> option, so numeric arguments to <code class="code">shift</code> |
| that exceed the number of positional parameters will result in an |
| error message. |
| |
| </li><li> When the <code class="code">alias</code> builtin displays alias definitions, it does not |
| display them with a leading ‘<samp class="samp">alias </samp>’ unless the <samp class="option">-p</samp> option |
| is supplied. |
| |
| </li><li> When the <code class="code">set</code> builtin is invoked without options, it does not display |
| shell function names and definitions. |
| |
| </li><li> When the <code class="code">set</code> builtin is invoked without options, it displays |
| variable values without quotes, unless they contain shell metacharacters, |
| even if the result contains nonprinting characters. |
| |
| </li><li> When the <code class="code">cd</code> builtin is invoked in logical mode, and the pathname |
| constructed from <code class="code">$PWD</code> and the directory name supplied as an argument |
| does not refer to an existing directory, <code class="code">cd</code> will fail instead of |
| falling back to physical mode. |
| |
| </li><li> When the <code class="code">cd</code> builtin cannot change a directory because the |
| length of the pathname |
| constructed from <code class="code">$PWD</code> and the directory name supplied as an argument |
| exceeds <code class="code">PATH_MAX</code> when all symbolic links are expanded, <code class="code">cd</code> will |
| fail instead of attempting to use only the supplied directory name. |
| |
| </li><li> The <code class="code">pwd</code> builtin verifies that the value it prints is the same as the |
| current directory, even if it is not asked to check the file system with the |
| <samp class="option">-P</samp> option. |
| |
| </li><li> When listing the history, the <code class="code">fc</code> builtin does not include an |
| indication of whether or not a history entry has been modified. |
| |
| </li><li> The default editor used by <code class="code">fc</code> is <code class="code">ed</code>. |
| |
| </li><li> The <code class="code">type</code> and <code class="code">command</code> builtins will not report a non-executable |
| file as having been found, though the shell will attempt to execute such a |
| file if it is the only so-named file found in <code class="code">$PATH</code>. |
| |
| </li><li> The <code class="code">vi</code> editing mode will invoke the <code class="code">vi</code> editor directly when |
| the ‘<samp class="samp">v</samp>’ command is run, instead of checking <code class="code">$VISUAL</code> and |
| <code class="code">$EDITOR</code>. |
| |
| </li><li> When the <code class="code">xpg_echo</code> option is enabled, Bash does not attempt to interpret |
| any arguments to <code class="code">echo</code> as options. Each argument is displayed, after |
| escape characters are converted. |
| |
| </li><li> The <code class="code">ulimit</code> builtin uses a block size of 512 bytes for the <samp class="option">-c</samp> |
| and <samp class="option">-f</samp> options. |
| |
| </li><li> The arrival of <code class="code">SIGCHLD</code> when a trap is set on <code class="code">SIGCHLD</code> does |
| not interrupt the <code class="code">wait</code> builtin and cause it to return immediately. |
| The trap command is run once for each child that exits. |
| |
| </li><li> The <code class="code">read</code> builtin may be interrupted by a signal for which a trap |
| has been set. |
| If Bash receives a trapped signal while executing <code class="code">read</code>, the trap |
| handler executes and <code class="code">read</code> returns an exit status greater than 128. |
| |
| </li><li> The <code class="code">printf</code> builtin uses <code class="code">double</code> (via <code class="code">strtod</code>) to convert |
| arguments corresponding to floating point conversion specifiers, instead of |
| <code class="code">long double</code> if it’s available. The ‘<samp class="samp">L</samp>’ length modifier forces |
| <code class="code">printf</code> to use <code class="code">long double</code> if it’s available. |
| |
| </li><li> Bash removes an exited background process’s status from the list of such |
| statuses after the <code class="code">wait</code> builtin is used to obtain it. |
| |
| </li></ol> |
| |
| <p>There is other <small class="sc">POSIX</small> behavior that Bash does not implement by |
| default even when in <small class="sc">POSIX</small> mode. |
| Specifically: |
| </p> |
| <ol class="enumerate"> |
| <li> The <code class="code">fc</code> builtin checks <code class="code">$EDITOR</code> as a program to edit history |
| entries if <code class="code">FCEDIT</code> is unset, rather than defaulting directly to |
| <code class="code">ed</code>. <code class="code">fc</code> uses <code class="code">ed</code> if <code class="code">EDITOR</code> is unset. |
| |
| </li><li> As noted above, Bash requires the <code class="code">xpg_echo</code> option to be enabled for |
| the <code class="code">echo</code> builtin to be fully conformant. |
| |
| </li></ol> |
| |
| <p>Bash can be configured to be <small class="sc">POSIX</small>-conformant by default, by specifying |
| the <samp class="option">--enable-strict-posix-default</samp> to <code class="code">configure</code> when building |
| (see <a class="pxref" href="#Optional-Features">Optional Features</a>). |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Shell-Compatibility-Mode"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Bash-POSIX-Mode" accesskey="p" rel="prev">Bash POSIX Mode</a>, Up: <a href="#Bash-Features" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Shell-Compatibility-Mode-1"><span>6.12 Shell Compatibility Mode<a class="copiable-link" href="#Shell-Compatibility-Mode-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-Compatibility-Level"></a> |
| <a class="index-entry-id" id="index-Compatibility-Mode"></a> |
| |
| <p>Bash-4.0 introduced the concept of a <em class="dfn">shell compatibility level</em>, |
| specified as a set of options to the shopt builtin |
| (<code class="code">compat31</code>, |
| <code class="code">compat32</code>, |
| <code class="code">compat40</code>, |
| <code class="code">compat41</code>, |
| and so on). |
| There is only one current |
| compatibility level – each option is mutually exclusive. |
| The compatibility level is intended to allow users to select behavior |
| from previous versions that is incompatible with newer versions |
| while they migrate scripts to use current features and |
| behavior. It’s intended to be a temporary solution. |
| </p> |
| <p>This section does not mention behavior that is standard for a particular |
| version (e.g., setting <code class="code">compat32</code> means that quoting the rhs of the regexp |
| matching operator quotes special regexp characters in the word, which is |
| default behavior in bash-3.2 and subsequent versions). |
| </p> |
| <p>If a user enables, say, <code class="code">compat32</code>, it may affect the behavior of other |
| compatibility levels up to and including the current compatibility level. |
| The idea is that each compatibility level controls behavior that changed |
| in that version of Bash, |
| but that behavior may have been present in earlier versions. |
| For instance, the change to use locale-based comparisons with the <code class="code">[[</code> |
| command came in bash-4.1, and earlier versions used ASCII-based comparisons, |
| so enabling <code class="code">compat32</code> will enable ASCII-based comparisons as well. |
| That granularity may not be sufficient for |
| all uses, and as a result users should employ compatibility levels carefully. |
| Read the documentation for a particular feature to find out the |
| current behavior. |
| </p> |
| <p>Bash-4.3 introduced a new shell variable: <code class="env">BASH_COMPAT</code>. |
| The value assigned |
| to this variable (a decimal version number like 4.2, or an integer |
| corresponding to the <code class="code">compat</code><var class="var">NN</var> option, like 42) determines the |
| compatibility level. |
| </p> |
| <p>Starting with bash-4.4, Bash has begun deprecating older compatibility |
| levels. |
| Eventually, the options will be removed in favor of <code class="env">BASH_COMPAT</code>. |
| </p> |
| <p>Bash-5.0 is the final version for which there will be an individual shopt |
| option for the previous version. Users should use <code class="env">BASH_COMPAT</code> |
| on bash-5.0 and later versions. |
| </p> |
| <p>The following table describes the behavior changes controlled by each |
| compatibility level setting. |
| The <code class="code">compat</code><var class="var">NN</var> tag is used as shorthand for setting the |
| compatibility level |
| to <var class="var">NN</var> using one of the following mechanisms. |
| For versions prior to bash-5.0, the compatibility level may be set using |
| the corresponding <code class="code">compat</code><var class="var">NN</var> shopt option. |
| For bash-4.3 and later versions, the <code class="env">BASH_COMPAT</code> variable is preferred, |
| and it is required for bash-5.1 and later versions. |
| </p> |
| <dl class="table"> |
| <dt><code class="code">compat31</code></dt> |
| <dd><ul class="itemize mark-bullet"> |
| <li>quoting the rhs of the <code class="code">[[</code> command’s regexp matching operator (=~) |
| has no special effect |
| </li></ul> |
| |
| </dd> |
| <dt><code class="code">compat32</code></dt> |
| <dd><ul class="itemize mark-bullet"> |
| <li>interrupting a command list such as "a ; b ; c" causes the execution |
| of the next command in the list (in bash-4.0 and later versions, |
| the shell acts as if it received the interrupt, so |
| interrupting one command in a list aborts the execution of the |
| entire list) |
| </li></ul> |
| |
| </dd> |
| <dt><code class="code">compat40</code></dt> |
| <dd><ul class="itemize mark-bullet"> |
| <li>the ‘<samp class="samp"><</samp>’ and ‘<samp class="samp">></samp>’ operators to the <code class="code">[[</code> command do not |
| consider the current locale when comparing strings; they use ASCII |
| ordering. |
| Bash versions prior to bash-4.1 use ASCII collation and strcmp(3); |
| bash-4.1 and later use the current locale’s collation sequence and |
| strcoll(3). |
| </li></ul> |
| |
| </dd> |
| <dt><code class="code">compat41</code></dt> |
| <dd><ul class="itemize mark-bullet"> |
| <li>in posix mode, <code class="code">time</code> may be followed by options and still be |
| recognized as a reserved word (this is <small class="sc">POSIX</small> interpretation 267) |
| </li><li>in posix mode, the parser requires that an even number of single |
| quotes occur in the <var class="var">word</var> portion of a double-quoted ${…} |
| parameter expansion and treats them specially, so that characters within |
| the single quotes are considered quoted |
| (this is <small class="sc">POSIX</small> interpretation 221) |
| </li></ul> |
| |
| </dd> |
| <dt><code class="code">compat42</code></dt> |
| <dd><ul class="itemize mark-bullet"> |
| <li>the replacement string in double-quoted pattern substitution does not |
| undergo quote removal, as it does in versions after bash-4.2 |
| </li><li>in posix mode, single quotes are considered special when expanding |
| the <var class="var">word</var> portion of a double-quoted ${…} parameter expansion |
| and can be used to quote a closing brace or other special character |
| (this is part of <small class="sc">POSIX</small> interpretation 221); |
| in later versions, single quotes |
| are not special within double-quoted word expansions |
| </li></ul> |
| |
| </dd> |
| <dt><code class="code">compat43</code></dt> |
| <dd><ul class="itemize mark-bullet"> |
| <li>the shell does not print a warning message if an attempt is made to |
| use a quoted compound assignment as an argument to declare |
| (e.g., declare -a foo=’(1 2)’). Later versions warn that this usage is |
| deprecated |
| </li><li>word expansion errors are considered non-fatal errors that cause the |
| current command to fail, even in posix mode |
| (the default behavior is to make them fatal errors that cause the shell |
| to exit) |
| </li><li>when executing a shell function, the loop state (while/until/etc.) |
| is not reset, so <code class="code">break</code> or <code class="code">continue</code> in that function will break |
| or continue loops in the calling context. Bash-4.4 and later reset |
| the loop state to prevent this |
| </li></ul> |
| |
| </dd> |
| <dt><code class="code">compat44</code></dt> |
| <dd><ul class="itemize mark-bullet"> |
| <li>the shell sets up the values used by <code class="env">BASH_ARGV</code> and <code class="env">BASH_ARGC</code> |
| so they can expand to the shell’s positional parameters even if extended |
| debugging mode is not enabled |
| </li><li>a subshell inherits loops from its parent context, so <code class="code">break</code> |
| or <code class="code">continue</code> will cause the subshell to exit. |
| Bash-5.0 and later reset the loop state to prevent the exit |
| </li><li>variable assignments preceding builtins like <code class="code">export</code> and <code class="code">readonly</code> |
| that set attributes continue to affect variables with the same |
| name in the calling environment even if the shell is not in posix |
| mode |
| </li></ul> |
| |
| </dd> |
| <dt><code class="code">compat50 (set using BASH_COMPAT)</code></dt> |
| <dd><ul class="itemize mark-bullet"> |
| <li>Bash-5.1 changed the way <code class="code">$RANDOM</code> is generated to introduce slightly |
| more randomness. If the shell compatibility level is set to 50 or |
| lower, it reverts to the method from bash-5.0 and previous versions, |
| so seeding the random number generator by assigning a value to |
| <code class="env">RANDOM</code> will produce the same sequence as in bash-5.0 |
| </li><li>If the command hash table is empty, Bash versions prior to bash-5.1 |
| printed an informational message to that effect, even when producing |
| output that can be reused as input. Bash-5.1 suppresses that message |
| when the <samp class="option">-l</samp> option is supplied. |
| </li></ul> |
| |
| </dd> |
| <dt><code class="code">compat51 (set using BASH_COMPAT)</code></dt> |
| <dd><ul class="itemize mark-bullet"> |
| <li>The <code class="code">unset</code> builtin will unset the array <code class="code">a</code> given an argument like |
| ‘<samp class="samp">a[@]</samp>’. |
| Bash-5.2 will unset an element with key ‘<samp class="samp">@</samp>’ (associative arrays) |
| or remove all the elements without unsetting the array (indexed arrays) |
| </li><li>arithmetic commands ( ((...)) ) and the expressions in an arithmetic for |
| statement can be expanded more than once |
| </li><li>expressions used as arguments to arithmetic operators in the <code class="code">[[</code> |
| conditional command can be expanded more than once |
| </li><li>the expressions in substring parameter brace expansion can be |
| expanded more than once |
| </li><li>the expressions in the $(( ... )) word expansion can be expanded |
| more than once |
| </li><li>arithmetic expressions used as indexed array subscripts can be |
| expanded more than once |
| </li><li><code class="code">test -v</code>, when given an argument of ‘<samp class="samp">A[@]</samp>’, where <var class="var">A</var> is |
| an existing associative array, will return true if the array has any set |
| elements. |
| Bash-5.2 will look for and report on a key named ‘<samp class="samp">@</samp>’ |
| </li><li>the ${<var class="var">parameter</var>[:]=<var class="var">value</var>} word expansion will return |
| <var class="var">value</var>, before any variable-specific transformations have been |
| performed (e.g., converting to lowercase). |
| Bash-5.2 will return the final value assigned to the variable. |
| </li><li>Parsing command substitutions will behave as if extended glob |
| (see <a class="pxref" href="#The-Shopt-Builtin">The Shopt Builtin</a>) |
| is enabled, so that parsing a command substitution containing an extglob |
| pattern (say, as part of a shell function) will not fail. |
| This assumes the intent is to enable extglob before the command is executed |
| and word expansions are performed. |
| It will fail at word expansion time if extglob hasn’t been |
| enabled by the time the command is executed. |
| </li></ul> |
| </dd> |
| </dl> |
| |
| <hr> |
| </div> |
| </div> |
| <div class="chapter-level-extent" id="Job-Control"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Command-Line-Editing" accesskey="n" rel="next">Command Line Editing</a>, Previous: <a href="#Bash-Features" accesskey="p" rel="prev">Bash Features</a>, Up: <a href="#Top" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h2 class="chapter" id="Job-Control-1"><span>7 Job Control<a class="copiable-link" href="#Job-Control-1"> ¶</a></span></h2> |
| |
| <p>This chapter discusses what job control is, how it works, and how |
| Bash allows you to access its facilities. |
| </p> |
| |
| <ul class="mini-toc"> |
| <li><a href="#Job-Control-Basics" accesskey="1">Job Control Basics</a></li> |
| <li><a href="#Job-Control-Builtins" accesskey="2">Job Control Builtins</a></li> |
| <li><a href="#Job-Control-Variables" accesskey="3">Job Control Variables</a></li> |
| </ul> |
| <hr> |
| <div class="section-level-extent" id="Job-Control-Basics"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Job-Control-Builtins" accesskey="n" rel="next">Job Control Builtins</a>, Up: <a href="#Job-Control" accesskey="u" rel="up">Job Control</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Job-Control-Basics-1"><span>7.1 Job Control Basics<a class="copiable-link" href="#Job-Control-Basics-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-job-control-1"></a> |
| <a class="index-entry-id" id="index-foreground"></a> |
| <a class="index-entry-id" id="index-background"></a> |
| <a class="index-entry-id" id="index-suspending-jobs"></a> |
| |
| <p>Job control |
| refers to the ability to selectively stop (suspend) |
| the execution of processes and continue (resume) |
| their execution at a later point. A user typically employs |
| this facility via an interactive interface supplied jointly |
| by the operating system kernel’s terminal driver and Bash. |
| </p> |
| <p>The shell associates a <var class="var">job</var> with each pipeline. It keeps a |
| table of currently executing jobs, which may be listed with the |
| <code class="code">jobs</code> command. When Bash starts a job |
| asynchronously, it prints a line that looks |
| like: |
| </p><div class="example"> |
| <pre class="example-preformatted">[1] 25647 |
| </pre></div> |
| <p>indicating that this job is job number 1 and that the process <small class="sc">ID</small> |
| of the last process in the pipeline associated with this job is |
| 25647. All of the processes in a single pipeline are members of |
| the same job. Bash uses the <var class="var">job</var> abstraction as the |
| basis for job control. |
| </p> |
| <p>To facilitate the implementation of the user interface to job |
| control, the operating system maintains the notion of a current terminal |
| process group <small class="sc">ID</small>. Members of this process group (processes whose |
| process group <small class="sc">ID</small> is equal to the current terminal process group |
| <small class="sc">ID</small>) receive keyboard-generated signals such as <code class="code">SIGINT</code>. |
| These processes are said to be in the foreground. Background |
| processes are those whose process group <small class="sc">ID</small> differs from the |
| terminal’s; such processes are immune to keyboard-generated |
| signals. Only foreground processes are allowed to read from or, if |
| the user so specifies with <code class="code">stty tostop</code>, write to the terminal. |
| Background processes which attempt to |
| read from (write to when <code class="code">stty tostop</code> is in effect) the |
| terminal are sent a <code class="code">SIGTTIN</code> (<code class="code">SIGTTOU</code>) |
| signal by the kernel’s terminal driver, |
| which, unless caught, suspends the process. |
| </p> |
| <p>If the operating system on which Bash is running supports |
| job control, Bash contains facilities to use it. Typing the |
| <em class="dfn">suspend</em> character (typically ‘<samp class="samp">^Z</samp>’, Control-Z) while a |
| process is running causes that process to be stopped and returns |
| control to Bash. Typing the <em class="dfn">delayed suspend</em> character |
| (typically ‘<samp class="samp">^Y</samp>’, Control-Y) causes the process to be stopped |
| when it attempts to read input from the terminal, and control to |
| be returned to Bash. The user then manipulates the state of |
| this job, using the <code class="code">bg</code> command to continue it in the |
| background, the <code class="code">fg</code> command to continue it in the |
| foreground, or the <code class="code">kill</code> command to kill it. A ‘<samp class="samp">^Z</samp>’ |
| takes effect immediately, and has the additional side effect of |
| causing pending output and typeahead to be discarded. |
| </p> |
| <p>There are a number of ways to refer to a job in the shell. The |
| character ‘<samp class="samp">%</samp>’ introduces a job specification (<em class="dfn">jobspec</em>). |
| </p> |
| <p>Job number <code class="code">n</code> may be referred to as ‘<samp class="samp">%n</samp>’. |
| The symbols ‘<samp class="samp">%%</samp>’ and ‘<samp class="samp">%+</samp>’ refer to the shell’s notion of the |
| current job, which is the last job stopped while it was in the foreground |
| or started in the background. |
| A single ‘<samp class="samp">%</samp>’ (with no accompanying job specification) also refers |
| to the current job. |
| The previous job may be referenced using ‘<samp class="samp">%-</samp>’. |
| If there is only a single job, ‘<samp class="samp">%+</samp>’ and ‘<samp class="samp">%-</samp>’ can both be used |
| to refer to that job. |
| In output pertaining to jobs (e.g., the output of the <code class="code">jobs</code> |
| command), the current job is always flagged with a ‘<samp class="samp">+</samp>’, and the |
| previous job with a ‘<samp class="samp">-</samp>’. |
| </p> |
| <p>A job may also be referred to |
| using a prefix of the name used to start it, or using a substring |
| that appears in its command line. For example, ‘<samp class="samp">%ce</samp>’ refers |
| to a stopped job whose command name begins with ‘<samp class="samp">ce</samp>’. |
| Using ‘<samp class="samp">%?ce</samp>’, on the |
| other hand, refers to any job containing the string ‘<samp class="samp">ce</samp>’ in |
| its command line. If the prefix or substring matches more than one job, |
| Bash reports an error. |
| </p> |
| <p>Simply naming a job can be used to bring it into the foreground: |
| ‘<samp class="samp">%1</samp>’ is a synonym for ‘<samp class="samp">fg %1</samp>’, bringing job 1 from the |
| background into the foreground. Similarly, ‘<samp class="samp">%1 &</samp>’ resumes |
| job 1 in the background, equivalent to ‘<samp class="samp">bg %1</samp>’ |
| </p> |
| <p>The shell learns immediately whenever a job changes state. |
| Normally, Bash waits until it is about to print a prompt |
| before reporting changes in a job’s status so as to not interrupt |
| any other output. |
| If the <samp class="option">-b</samp> option to the <code class="code">set</code> builtin is enabled, |
| Bash reports such changes immediately (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>). |
| Any trap on <code class="code">SIGCHLD</code> is executed for each child process |
| that exits. |
| </p> |
| <p>If an attempt to exit Bash is made while jobs are stopped, (or running, if |
| the <code class="code">checkjobs</code> option is enabled – see <a class="ref" href="#The-Shopt-Builtin">The Shopt Builtin</a>), the |
| shell prints a warning message, and if the <code class="code">checkjobs</code> option is |
| enabled, lists the jobs and their statuses. |
| The <code class="code">jobs</code> command may then be used to inspect their status. |
| If a second attempt to exit is made without an intervening command, |
| Bash does not print another warning, and any stopped jobs are terminated. |
| </p> |
| <p>When the shell is waiting for a job or process using the <code class="code">wait</code> |
| builtin, and job control is enabled, <code class="code">wait</code> will return when the |
| job changes state. The <samp class="option">-f</samp> option causes <code class="code">wait</code> to wait |
| until the job or process terminates before returning. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Job-Control-Builtins"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Job-Control-Variables" accesskey="n" rel="next">Job Control Variables</a>, Previous: <a href="#Job-Control-Basics" accesskey="p" rel="prev">Job Control Basics</a>, Up: <a href="#Job-Control" accesskey="u" rel="up">Job Control</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Job-Control-Builtins-1"><span>7.2 Job Control Builtins<a class="copiable-link" href="#Job-Control-Builtins-1"> ¶</a></span></h3> |
| |
| <dl class="table"> |
| <dt><a id="index-bg"></a><span><code class="code">bg</code><a class="copiable-link" href="#index-bg"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">bg [<var class="var">jobspec</var> ...] |
| </pre></div> |
| |
| <p>Resume each suspended job <var class="var">jobspec</var> in the background, as if it |
| had been started with ‘<samp class="samp">&</samp>’. |
| If <var class="var">jobspec</var> is not supplied, the current job is used. |
| The return status is zero unless it is run when job control is not |
| enabled, or, when run with job control enabled, any |
| <var class="var">jobspec</var> was not found or specifies a job |
| that was started without job control. |
| </p> |
| </dd> |
| <dt><a id="index-fg"></a><span><code class="code">fg</code><a class="copiable-link" href="#index-fg"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">fg [<var class="var">jobspec</var>] |
| </pre></div> |
| |
| <p>Resume the job <var class="var">jobspec</var> in the foreground and make it the current job. |
| If <var class="var">jobspec</var> is not supplied, the current job is used. |
| The return status is that of the command placed into the foreground, |
| or non-zero if run when job control is disabled or, when run with |
| job control enabled, <var class="var">jobspec</var> does not specify a valid job or |
| <var class="var">jobspec</var> specifies a job that was started without job control. |
| </p> |
| </dd> |
| <dt><a id="index-jobs"></a><span><code class="code">jobs</code><a class="copiable-link" href="#index-jobs"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">jobs [-lnprs] [<var class="var">jobspec</var>] |
| jobs -x <var class="var">command</var> [<var class="var">arguments</var>] |
| </pre></div> |
| |
| <p>The first form lists the active jobs. The options have the |
| following meanings: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">-l</code></dt> |
| <dd><p>List process <small class="sc">ID</small>s in addition to the normal information. |
| </p> |
| </dd> |
| <dt><code class="code">-n</code></dt> |
| <dd><p>Display information only about jobs that have changed status since |
| the user was last notified of their status. |
| </p> |
| </dd> |
| <dt><code class="code">-p</code></dt> |
| <dd><p>List only the process <small class="sc">ID</small> of the job’s process group leader. |
| </p> |
| </dd> |
| <dt><code class="code">-r</code></dt> |
| <dd><p>Display only running jobs. |
| </p> |
| </dd> |
| <dt><code class="code">-s</code></dt> |
| <dd><p>Display only stopped jobs. |
| </p></dd> |
| </dl> |
| |
| <p>If <var class="var">jobspec</var> is given, |
| output is restricted to information about that job. |
| If <var class="var">jobspec</var> is not supplied, the status of all jobs is |
| listed. |
| </p> |
| <p>If the <samp class="option">-x</samp> option is supplied, <code class="code">jobs</code> replaces any |
| <var class="var">jobspec</var> found in <var class="var">command</var> or <var class="var">arguments</var> with the |
| corresponding process group <small class="sc">ID</small>, and executes <var class="var">command</var>, |
| passing it <var class="var">argument</var>s, returning its exit status. |
| </p> |
| </dd> |
| <dt><a id="index-kill"></a><span><code class="code">kill</code><a class="copiable-link" href="#index-kill"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">kill [-s <var class="var">sigspec</var>] [-n <var class="var">signum</var>] [-<var class="var">sigspec</var>] <var class="var">jobspec</var> or <var class="var">pid</var> |
| kill -l|-L [<var class="var">exit_status</var>] |
| </pre></div> |
| |
| <p>Send a signal specified by <var class="var">sigspec</var> or <var class="var">signum</var> to the process |
| named by job specification <var class="var">jobspec</var> or process <small class="sc">ID</small> <var class="var">pid</var>. |
| <var class="var">sigspec</var> is either a case-insensitive signal name such as |
| <code class="code">SIGINT</code> (with or without the <code class="code">SIG</code> prefix) |
| or a signal number; <var class="var">signum</var> is a signal number. |
| If <var class="var">sigspec</var> and <var class="var">signum</var> are not present, <code class="code">SIGTERM</code> is used. |
| The <samp class="option">-l</samp> option lists the signal names. |
| If any arguments are supplied when <samp class="option">-l</samp> is given, the names of the |
| signals corresponding to the arguments are listed, and the return status |
| is zero. |
| <var class="var">exit_status</var> is a number specifying a signal number or the exit |
| status of a process terminated by a signal. |
| The <samp class="option">-L</samp> option is equivalent to <samp class="option">-l</samp>. |
| The return status is zero if at least one signal was successfully sent, |
| or non-zero if an error occurs or an invalid option is encountered. |
| </p> |
| </dd> |
| <dt><a id="index-wait"></a><span><code class="code">wait</code><a class="copiable-link" href="#index-wait"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">wait [-fn] [-p <var class="var">varname</var>] [<var class="var">jobspec</var> or <var class="var">pid</var> ...] |
| </pre></div> |
| |
| <p>Wait until the child process specified by each process <small class="sc">ID</small> <var class="var">pid</var> |
| or job specification <var class="var">jobspec</var> exits and return the exit status of the |
| last command waited for. |
| If a job spec is given, all processes in the job are waited for. |
| If no arguments are given, |
| <code class="code">wait</code> waits for all running background jobs and |
| the last-executed process substitution, if its process id is the same as |
| <var class="var">$!</var>, |
| and the return status is zero. |
| If the <samp class="option">-n</samp> option is supplied, <code class="code">wait</code> waits for a single job |
| from the list of <var class="var">pid</var>s or <var class="var">jobspec</var>s or, if no arguments are |
| supplied, any job, |
| to complete and returns its exit status. |
| If none of the supplied arguments is a child of the shell, or if no arguments |
| are supplied and the shell has no unwaited-for children, the exit status |
| is 127. |
| If the <samp class="option">-p</samp> option is supplied, the process or job identifier of the job |
| for which the exit status is returned is assigned to the variable |
| <var class="var">varname</var> named by the option argument. |
| The variable will be unset initially, before any assignment. |
| This is useful only when the <samp class="option">-n</samp> option is supplied. |
| Supplying the <samp class="option">-f</samp> option, when job control is enabled, |
| forces <code class="code">wait</code> to wait for each <var class="var">pid</var> or <var class="var">jobspec</var> to |
| terminate before returning its status, instead of returning when it changes |
| status. |
| If neither <var class="var">jobspec</var> nor <var class="var">pid</var> specifies an active child process |
| of the shell, the return status is 127. |
| If <code class="code">wait</code> is interrupted by a signal, the return status will be greater |
| than 128, as described above (see <a class="pxref" href="#Signals">Signals</a>). |
| Otherwise, the return status is the exit status |
| of the last process or job waited for. |
| </p> |
| </dd> |
| <dt><a id="index-disown"></a><span><code class="code">disown</code><a class="copiable-link" href="#index-disown"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">disown [-ar] [-h] [<var class="var">jobspec</var> ... | <var class="var">pid</var> ... ] |
| </pre></div> |
| |
| <p>Without options, remove each <var class="var">jobspec</var> from the table of |
| active jobs. |
| If the <samp class="option">-h</samp> option is given, the job is not removed from the table, |
| but is marked so that <code class="code">SIGHUP</code> is not sent to the job if the shell |
| receives a <code class="code">SIGHUP</code>. |
| If <var class="var">jobspec</var> is not present, and neither the <samp class="option">-a</samp> nor the |
| <samp class="option">-r</samp> option is supplied, the current job is used. |
| If no <var class="var">jobspec</var> is supplied, the <samp class="option">-a</samp> option means to remove or |
| mark all jobs; the <samp class="option">-r</samp> option without a <var class="var">jobspec</var> |
| argument restricts operation to running jobs. |
| </p> |
| </dd> |
| <dt><a id="index-suspend"></a><span><code class="code">suspend</code><a class="copiable-link" href="#index-suspend"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">suspend [-f] |
| </pre></div> |
| |
| <p>Suspend the execution of this shell until it receives a |
| <code class="code">SIGCONT</code> signal. |
| A login shell, |
| or a shell without job control enabled, |
| cannot be suspended; the <samp class="option">-f</samp> |
| option can be used to override this and force the suspension. |
| The return status is 0 unless the shell is a login shell |
| or job control is not enabled |
| and |
| <samp class="option">-f</samp> |
| is not supplied. |
| </p> |
| </dd> |
| </dl> |
| |
| <p>When job control is not active, the <code class="code">kill</code> and <code class="code">wait</code> |
| builtins do not accept <var class="var">jobspec</var> arguments. They must be |
| supplied process <small class="sc">ID</small>s. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Job-Control-Variables"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Job-Control-Builtins" accesskey="p" rel="prev">Job Control Builtins</a>, Up: <a href="#Job-Control" accesskey="u" rel="up">Job Control</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Job-Control-Variables-1"><span>7.3 Job Control Variables<a class="copiable-link" href="#Job-Control-Variables-1"> ¶</a></span></h3> |
| |
| <dl class="vtable"> |
| <dt><a id="index-auto_005fresume"></a><span><code class="code">auto_resume</code><a class="copiable-link" href="#index-auto_005fresume"> ¶</a></span></dt> |
| <dd><p>This variable controls how the shell interacts with the user and |
| job control. If this variable exists then single word simple |
| commands without redirections are treated as candidates for resumption |
| of an existing job. There is no ambiguity allowed; if there is |
| more than one job beginning with the string typed, then |
| the most recently accessed job will be selected. |
| The name of a stopped job, in this context, is the command line |
| used to start it. If this variable is set to the value ‘<samp class="samp">exact</samp>’, |
| the string supplied must match the name of a stopped job exactly; |
| if set to ‘<samp class="samp">substring</samp>’, |
| the string supplied needs to match a substring of the name of a |
| stopped job. The ‘<samp class="samp">substring</samp>’ value provides functionality |
| analogous to the ‘<samp class="samp">%?</samp>’ job <small class="sc">ID</small> (see <a class="pxref" href="#Job-Control-Basics">Job Control Basics</a>). |
| If set to any other value, the supplied string must |
| be a prefix of a stopped job’s name; this provides functionality |
| analogous to the ‘<samp class="samp">%</samp>’ job <small class="sc">ID</small>. |
| </p> |
| </dd> |
| </dl> |
| |
| <a class="index-entry-id" id="index-Readline_002c-how-to-use"></a> |
| |
| |
| |
| |
| <hr> |
| </div> |
| </div> |
| <div class="chapter-level-extent" id="Command-Line-Editing"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Using-History-Interactively" accesskey="n" rel="next">Using History Interactively</a>, Previous: <a href="#Job-Control" accesskey="p" rel="prev">Job Control</a>, Up: <a href="#Top" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h2 class="chapter" id="Command-Line-Editing-1"><span>8 Command Line Editing<a class="copiable-link" href="#Command-Line-Editing-1"> ¶</a></span></h2> |
| |
| <p>This chapter describes the basic features of the <small class="sc">GNU</small> |
| command line editing interface. |
| Command line editing is provided by the Readline library, which is |
| used by several different programs, including Bash. |
| Command line editing is enabled by default when using an interactive shell, |
| unless the <samp class="option">--noediting</samp> option is supplied at shell invocation. |
| Line editing is also used when using the <samp class="option">-e</samp> option to the |
| <code class="code">read</code> builtin command (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>). |
| By default, the line editing commands are similar to those of Emacs. |
| A vi-style line editing interface is also available. |
| Line editing can be enabled at any time using the <samp class="option">-o emacs</samp> or |
| <samp class="option">-o vi</samp> options to the <code class="code">set</code> builtin command |
| (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>), or disabled using the <samp class="option">+o emacs</samp> or |
| <samp class="option">+o vi</samp> options to <code class="code">set</code>. |
| </p> |
| |
| <ul class="mini-toc"> |
| <li><a href="#Introduction-and-Notation" accesskey="1">Introduction to Line Editing</a></li> |
| <li><a href="#Readline-Interaction" accesskey="2">Readline Interaction</a></li> |
| <li><a href="#Readline-Init-File" accesskey="3">Readline Init File</a></li> |
| <li><a href="#Bindable-Readline-Commands" accesskey="4">Bindable Readline Commands</a></li> |
| <li><a href="#Readline-vi-Mode" accesskey="5">Readline vi Mode</a></li> |
| <li><a href="#Programmable-Completion" accesskey="6">Programmable Completion</a></li> |
| <li><a href="#Programmable-Completion-Builtins" accesskey="7">Programmable Completion Builtins</a></li> |
| <li><a href="#A-Programmable-Completion-Example" accesskey="8">A Programmable Completion Example</a></li> |
| </ul> |
| <hr> |
| <div class="section-level-extent" id="Introduction-and-Notation"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Readline-Interaction" accesskey="n" rel="next">Readline Interaction</a>, Up: <a href="#Command-Line-Editing" accesskey="u" rel="up">Command Line Editing</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Introduction-to-Line-Editing"><span>8.1 Introduction to Line Editing<a class="copiable-link" href="#Introduction-to-Line-Editing"> ¶</a></span></h3> |
| |
| <p>The following paragraphs describe the notation used to represent |
| keystrokes. |
| </p> |
| <p>The text <kbd class="kbd">C-k</kbd> is read as ‘Control-K’ and describes the character |
| produced when the <kbd class="key">k</kbd> key is pressed while the Control key |
| is depressed. |
| </p> |
| <p>The text <kbd class="kbd">M-k</kbd> is read as ‘Meta-K’ and describes the character |
| produced when the Meta key (if you have one) is depressed, and the <kbd class="key">k</kbd> |
| key is pressed. |
| The Meta key is labeled <kbd class="key">ALT</kbd> on many keyboards. |
| On keyboards with two keys labeled <kbd class="key">ALT</kbd> (usually to either side of |
| the space bar), the <kbd class="key">ALT</kbd> on the left side is generally set to |
| work as a Meta key. |
| The <kbd class="key">ALT</kbd> key on the right may also be configured to work as a |
| Meta key or may be configured as some other modifier, such as a |
| Compose key for typing accented characters. |
| </p> |
| <p>If you do not have a Meta or <kbd class="key">ALT</kbd> key, or another key working as |
| a Meta key, the identical keystroke can be generated by typing <kbd class="key">ESC</kbd> |
| <em class="emph">first</em>, and then typing <kbd class="key">k</kbd>. |
| Either process is known as <em class="dfn">metafying</em> the <kbd class="key">k</kbd> key. |
| </p> |
| <p>The text <kbd class="kbd">M-C-k</kbd> is read as ‘Meta-Control-k’ and describes the |
| character produced by <em class="dfn">metafying</em> <kbd class="kbd">C-k</kbd>. |
| </p> |
| <p>In addition, several keys have their own names. Specifically, |
| <kbd class="key">DEL</kbd>, <kbd class="key">ESC</kbd>, <kbd class="key">LFD</kbd>, <kbd class="key">SPC</kbd>, <kbd class="key">RET</kbd>, and <kbd class="key">TAB</kbd> all |
| stand for themselves when seen in this text, or in an init file |
| (see <a class="pxref" href="#Readline-Init-File">Readline Init File</a>). |
| If your keyboard lacks a <kbd class="key">LFD</kbd> key, typing <kbd class="key">C-j</kbd> will |
| produce the desired character. |
| The <kbd class="key">RET</kbd> key may be labeled <kbd class="key">Return</kbd> or <kbd class="key">Enter</kbd> on |
| some keyboards. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Readline-Interaction"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Readline-Init-File" accesskey="n" rel="next">Readline Init File</a>, Previous: <a href="#Introduction-and-Notation" accesskey="p" rel="prev">Introduction to Line Editing</a>, Up: <a href="#Command-Line-Editing" accesskey="u" rel="up">Command Line Editing</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Readline-Interaction-1"><span>8.2 Readline Interaction<a class="copiable-link" href="#Readline-Interaction-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-interaction_002c-readline"></a> |
| |
| <p>Often during an interactive session you type in a long line of text, |
| only to notice that the first word on the line is misspelled. The |
| Readline library gives you a set of commands for manipulating the text |
| as you type it in, allowing you to just fix your typo, and not forcing |
| you to retype the majority of the line. Using these editing commands, |
| you move the cursor to the place that needs correction, and delete or |
| insert the text of the corrections. Then, when you are satisfied with |
| the line, you simply press <kbd class="key">RET</kbd>. You do not have to be at the |
| end of the line to press <kbd class="key">RET</kbd>; the entire line is accepted |
| regardless of the location of the cursor within the line. |
| </p> |
| |
| <ul class="mini-toc"> |
| <li><a href="#Readline-Bare-Essentials" accesskey="1">Readline Bare Essentials</a></li> |
| <li><a href="#Readline-Movement-Commands" accesskey="2">Readline Movement Commands</a></li> |
| <li><a href="#Readline-Killing-Commands" accesskey="3">Readline Killing Commands</a></li> |
| <li><a href="#Readline-Arguments" accesskey="4">Readline Arguments</a></li> |
| <li><a href="#Searching" accesskey="5">Searching for Commands in the History</a></li> |
| </ul> |
| <hr> |
| <div class="subsection-level-extent" id="Readline-Bare-Essentials"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Readline-Movement-Commands" accesskey="n" rel="next">Readline Movement Commands</a>, Up: <a href="#Readline-Interaction" accesskey="u" rel="up">Readline Interaction</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Readline-Bare-Essentials-1"><span>8.2.1 Readline Bare Essentials<a class="copiable-link" href="#Readline-Bare-Essentials-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-notation_002c-readline"></a> |
| <a class="index-entry-id" id="index-command-editing"></a> |
| <a class="index-entry-id" id="index-editing-command-lines"></a> |
| |
| <p>In order to enter characters into the line, simply type them. The typed |
| character appears where the cursor was, and then the cursor moves one |
| space to the right. If you mistype a character, you can use your |
| erase character to back up and delete the mistyped character. |
| </p> |
| <p>Sometimes you may mistype a character, and |
| not notice the error until you have typed several other characters. In |
| that case, you can type <kbd class="kbd">C-b</kbd> to move the cursor to the left, and then |
| correct your mistake. Afterwards, you can move the cursor to the right |
| with <kbd class="kbd">C-f</kbd>. |
| </p> |
| <p>When you add text in the middle of a line, you will notice that characters |
| to the right of the cursor are ‘pushed over’ to make room for the text |
| that you have inserted. Likewise, when you delete text behind the cursor, |
| characters to the right of the cursor are ‘pulled back’ to fill in the |
| blank space created by the removal of the text. A list of the bare |
| essentials for editing the text of an input line follows. |
| </p> |
| <dl class="table"> |
| <dt><kbd class="kbd">C-b</kbd></dt> |
| <dd><p>Move back one character. |
| </p></dd> |
| <dt><kbd class="kbd">C-f</kbd></dt> |
| <dd><p>Move forward one character. |
| </p></dd> |
| <dt><kbd class="key">DEL</kbd> or <kbd class="key">Backspace</kbd></dt> |
| <dd><p>Delete the character to the left of the cursor. |
| </p></dd> |
| <dt><kbd class="kbd">C-d</kbd></dt> |
| <dd><p>Delete the character underneath the cursor. |
| </p></dd> |
| <dt>Printing characters<!-- /@w --></dt> |
| <dd><p>Insert the character into the line at the cursor. |
| </p></dd> |
| <dt><kbd class="kbd">C-_</kbd> or <kbd class="kbd">C-x C-u</kbd></dt> |
| <dd><p>Undo the last editing command. You can undo all the way back to an |
| empty line. |
| </p></dd> |
| </dl> |
| |
| <p>(Depending on your configuration, the <kbd class="key">Backspace</kbd> key might be set to |
| delete the character to the left of the cursor and the <kbd class="key">DEL</kbd> key set |
| to delete the character underneath the cursor, like <kbd class="kbd">C-d</kbd>, rather |
| than the character to the left of the cursor.) |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Readline-Movement-Commands"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Readline-Killing-Commands" accesskey="n" rel="next">Readline Killing Commands</a>, Previous: <a href="#Readline-Bare-Essentials" accesskey="p" rel="prev">Readline Bare Essentials</a>, Up: <a href="#Readline-Interaction" accesskey="u" rel="up">Readline Interaction</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Readline-Movement-Commands-1"><span>8.2.2 Readline Movement Commands<a class="copiable-link" href="#Readline-Movement-Commands-1"> ¶</a></span></h4> |
| |
| |
| <p>The above table describes the most basic keystrokes that you need |
| in order to do editing of the input line. For your convenience, many |
| other commands have been added in addition to <kbd class="kbd">C-b</kbd>, <kbd class="kbd">C-f</kbd>, |
| <kbd class="kbd">C-d</kbd>, and <kbd class="key">DEL</kbd>. Here are some commands for moving more rapidly |
| about the line. |
| </p> |
| <dl class="table"> |
| <dt><kbd class="kbd">C-a</kbd></dt> |
| <dd><p>Move to the start of the line. |
| </p></dd> |
| <dt><kbd class="kbd">C-e</kbd></dt> |
| <dd><p>Move to the end of the line. |
| </p></dd> |
| <dt><kbd class="kbd">M-f</kbd></dt> |
| <dd><p>Move forward a word, where a word is composed of letters and digits. |
| </p></dd> |
| <dt><kbd class="kbd">M-b</kbd></dt> |
| <dd><p>Move backward a word. |
| </p></dd> |
| <dt><kbd class="kbd">C-l</kbd></dt> |
| <dd><p>Clear the screen, reprinting the current line at the top. |
| </p></dd> |
| </dl> |
| |
| <p>Notice how <kbd class="kbd">C-f</kbd> moves forward a character, while <kbd class="kbd">M-f</kbd> moves |
| forward a word. It is a loose convention that control keystrokes |
| operate on characters while meta keystrokes operate on words. |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Readline-Killing-Commands"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Readline-Arguments" accesskey="n" rel="next">Readline Arguments</a>, Previous: <a href="#Readline-Movement-Commands" accesskey="p" rel="prev">Readline Movement Commands</a>, Up: <a href="#Readline-Interaction" accesskey="u" rel="up">Readline Interaction</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Readline-Killing-Commands-1"><span>8.2.3 Readline Killing Commands<a class="copiable-link" href="#Readline-Killing-Commands-1"> ¶</a></span></h4> |
| |
| <a class="index-entry-id" id="index-killing-text"></a> |
| <a class="index-entry-id" id="index-yanking-text"></a> |
| |
| <p><em class="dfn">Killing</em> text means to delete the text from the line, but to save |
| it away for later use, usually by <em class="dfn">yanking</em> (re-inserting) |
| it back into the line. |
| (‘Cut’ and ‘paste’ are more recent jargon for ‘kill’ and ‘yank’.) |
| </p> |
| <p>If the description for a command says that it ‘kills’ text, then you can |
| be sure that you can get the text back in a different (or the same) |
| place later. |
| </p> |
| <p>When you use a kill command, the text is saved in a <em class="dfn">kill-ring</em>. |
| Any number of consecutive kills save all of the killed text together, so |
| that when you yank it back, you get it all. The kill |
| ring is not line specific; the text that you killed on a previously |
| typed line is available to be yanked back later, when you are typing |
| another line. |
| <a class="index-entry-id" id="index-kill-ring"></a> |
| </p> |
| <p>Here is the list of commands for killing text. |
| </p> |
| <dl class="table"> |
| <dt><kbd class="kbd">C-k</kbd></dt> |
| <dd><p>Kill the text from the current cursor position to the end of the line. |
| </p> |
| </dd> |
| <dt><kbd class="kbd">M-d</kbd></dt> |
| <dd><p>Kill from the cursor to the end of the current word, or, if between |
| words, to the end of the next word. |
| Word boundaries are the same as those used by <kbd class="kbd">M-f</kbd>. |
| </p> |
| </dd> |
| <dt><kbd class="kbd">M-<kbd class="key">DEL</kbd></kbd></dt> |
| <dd><p>Kill from the cursor to the start of the current word, or, if between |
| words, to the start of the previous word. |
| Word boundaries are the same as those used by <kbd class="kbd">M-b</kbd>. |
| </p> |
| </dd> |
| <dt><kbd class="kbd">C-w</kbd></dt> |
| <dd><p>Kill from the cursor to the previous whitespace. This is different than |
| <kbd class="kbd">M-<kbd class="key">DEL</kbd></kbd> because the word boundaries differ. |
| </p> |
| </dd> |
| </dl> |
| |
| <p>Here is how to <em class="dfn">yank</em> the text back into the line. Yanking |
| means to copy the most-recently-killed text from the kill buffer. |
| </p> |
| <dl class="table"> |
| <dt><kbd class="kbd">C-y</kbd></dt> |
| <dd><p>Yank the most recently killed text back into the buffer at the cursor. |
| </p> |
| </dd> |
| <dt><kbd class="kbd">M-y</kbd></dt> |
| <dd><p>Rotate the kill-ring, and yank the new top. You can only do this if |
| the prior command is <kbd class="kbd">C-y</kbd> or <kbd class="kbd">M-y</kbd>. |
| </p></dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Readline-Arguments"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Searching" accesskey="n" rel="next">Searching for Commands in the History</a>, Previous: <a href="#Readline-Killing-Commands" accesskey="p" rel="prev">Readline Killing Commands</a>, Up: <a href="#Readline-Interaction" accesskey="u" rel="up">Readline Interaction</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Readline-Arguments-1"><span>8.2.4 Readline Arguments<a class="copiable-link" href="#Readline-Arguments-1"> ¶</a></span></h4> |
| |
| <p>You can pass numeric arguments to Readline commands. Sometimes the |
| argument acts as a repeat count, other times it is the <i class="i">sign</i> of the |
| argument that is significant. If you pass a negative argument to a |
| command which normally acts in a forward direction, that command will |
| act in a backward direction. For example, to kill text back to the |
| start of the line, you might type ‘<samp class="samp">M-- C-k</samp>’. |
| </p> |
| <p>The general way to pass numeric arguments to a command is to type meta |
| digits before the command. If the first ‘digit’ typed is a minus |
| sign (‘<samp class="samp">-</samp>’), then the sign of the argument will be negative. Once |
| you have typed one meta digit to get the argument started, you can type |
| the remainder of the digits, and then the command. For example, to give |
| the <kbd class="kbd">C-d</kbd> command an argument of 10, you could type ‘<samp class="samp">M-1 0 C-d</samp>’, |
| which will delete the next ten characters on the input line. |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Searching"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Readline-Arguments" accesskey="p" rel="prev">Readline Arguments</a>, Up: <a href="#Readline-Interaction" accesskey="u" rel="up">Readline Interaction</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Searching-for-Commands-in-the-History"><span>8.2.5 Searching for Commands in the History<a class="copiable-link" href="#Searching-for-Commands-in-the-History"> ¶</a></span></h4> |
| |
| <p>Readline provides commands for searching through the command history |
| (see <a class="pxref" href="#Bash-History-Facilities">Bash History Facilities</a>) |
| for lines containing a specified string. |
| There are two search modes: <em class="dfn">incremental</em> and <em class="dfn">non-incremental</em>. |
| </p> |
| <p>Incremental searches begin before the user has finished typing the |
| search string. |
| As each character of the search string is typed, Readline displays |
| the next entry from the history matching the string typed so far. |
| An incremental search requires only as many characters as needed to |
| find the desired history entry. |
| To search backward in the history for a particular string, type |
| <kbd class="kbd">C-r</kbd>. Typing <kbd class="kbd">C-s</kbd> searches forward through the history. |
| The characters present in the value of the <code class="code">isearch-terminators</code> variable |
| are used to terminate an incremental search. |
| If that variable has not been assigned a value, the <kbd class="key">ESC</kbd> and |
| <kbd class="kbd">C-J</kbd> characters will terminate an incremental search. |
| <kbd class="kbd">C-g</kbd> will abort an incremental search and restore the original line. |
| When the search is terminated, the history entry containing the |
| search string becomes the current line. |
| </p> |
| <p>To find other matching entries in the history list, type <kbd class="kbd">C-r</kbd> or |
| <kbd class="kbd">C-s</kbd> as appropriate. |
| This will search backward or forward in the history for the next |
| entry matching the search string typed so far. |
| Any other key sequence bound to a Readline command will terminate |
| the search and execute that command. |
| For instance, a <kbd class="key">RET</kbd> will terminate the search and accept |
| the line, thereby executing the command from the history list. |
| A movement command will terminate the search, make the last line found |
| the current line, and begin editing. |
| </p> |
| <p>Readline remembers the last incremental search string. If two |
| <kbd class="kbd">C-r</kbd>s are typed without any intervening characters defining a new |
| search string, any remembered search string is used. |
| </p> |
| <p>Non-incremental searches read the entire search string before starting |
| to search for matching history lines. The search string may be |
| typed by the user or be part of the contents of the current line. |
| </p> |
| <hr> |
| </div> |
| </div> |
| <div class="section-level-extent" id="Readline-Init-File"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Bindable-Readline-Commands" accesskey="n" rel="next">Bindable Readline Commands</a>, Previous: <a href="#Readline-Interaction" accesskey="p" rel="prev">Readline Interaction</a>, Up: <a href="#Command-Line-Editing" accesskey="u" rel="up">Command Line Editing</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Readline-Init-File-1"><span>8.3 Readline Init File<a class="copiable-link" href="#Readline-Init-File-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-initialization-file_002c-readline"></a> |
| |
| <p>Although the Readline library comes with a set of Emacs-like |
| keybindings installed by default, it is possible to use a different set |
| of keybindings. |
| Any user can customize programs that use Readline by putting |
| commands in an <em class="dfn">inputrc</em> file, |
| conventionally in their home directory. |
| The name of this |
| file is taken from the value of the shell variable <code class="env">INPUTRC</code>. If |
| that variable is unset, the default is <samp class="file">~/.inputrc</samp>. If that |
| file does not exist or cannot be read, the ultimate default is |
| <samp class="file">/etc/inputrc</samp>. |
| The <code class="code">bind</code><!-- /@w --> builtin command can also be used to set Readline |
| keybindings and variables. |
| See <a class="xref" href="#Bash-Builtins">Bash Builtin Commands</a>. |
| </p> |
| <p>When a program which uses the Readline library starts up, the |
| init file is read, and the key bindings are set. |
| </p> |
| <p>In addition, the <code class="code">C-x C-r</code> command re-reads this init file, thus |
| incorporating any changes that you might have made to it. |
| </p> |
| |
| <ul class="mini-toc"> |
| <li><a href="#Readline-Init-File-Syntax" accesskey="1">Readline Init File Syntax</a></li> |
| <li><a href="#Conditional-Init-Constructs" accesskey="2">Conditional Init Constructs</a></li> |
| <li><a href="#Sample-Init-File" accesskey="3">Sample Init File</a></li> |
| </ul> |
| <hr> |
| <div class="subsection-level-extent" id="Readline-Init-File-Syntax"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Conditional-Init-Constructs" accesskey="n" rel="next">Conditional Init Constructs</a>, Up: <a href="#Readline-Init-File" accesskey="u" rel="up">Readline Init File</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Readline-Init-File-Syntax-1"><span>8.3.1 Readline Init File Syntax<a class="copiable-link" href="#Readline-Init-File-Syntax-1"> ¶</a></span></h4> |
| |
| <p>There are only a few basic constructs allowed in the |
| Readline init file. Blank lines are ignored. |
| Lines beginning with a ‘<samp class="samp">#</samp>’ are comments. |
| Lines beginning with a ‘<samp class="samp">$</samp>’ indicate conditional |
| constructs (see <a class="pxref" href="#Conditional-Init-Constructs">Conditional Init Constructs</a>). Other lines |
| denote variable settings and key bindings. |
| </p> |
| <dl class="table"> |
| <dt>Variable Settings</dt> |
| <dd><p>You can modify the run-time behavior of Readline by |
| altering the values of variables in Readline |
| using the <code class="code">set</code> command within the init file. |
| The syntax is simple: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">set <var class="var">variable</var> <var class="var">value</var> |
| </pre></div> |
| |
| <p>Here, for example, is how to |
| change from the default Emacs-like key binding to use |
| <code class="code">vi</code> line editing commands: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">set editing-mode vi |
| </pre></div> |
| |
| <p>Variable names and values, where appropriate, are recognized without regard |
| to case. Unrecognized variable names are ignored. |
| </p> |
| <p>Boolean variables (those that can be set to on or off) are set to on if |
| the value is null or empty, <var class="var">on</var> (case-insensitive), or 1. Any other |
| value results in the variable being set to off. |
| </p> |
| <p>The <code class="code">bind -V</code><!-- /@w --> command lists the current Readline variable names |
| and values. See <a class="xref" href="#Bash-Builtins">Bash Builtin Commands</a>. |
| </p> |
| <p>A great deal of run-time behavior is changeable with the following |
| variables. |
| </p> |
| <a class="index-entry-id" id="index-variables_002c-readline"></a> |
| <dl class="table"> |
| <dt><a id="index-active_002dregion_002dstart_002dcolor"></a><span><code class="code">active-region-start-color</code><a class="copiable-link" href="#index-active_002dregion_002dstart_002dcolor"> ¶</a></span></dt> |
| <dd><p>A string variable that controls the text color and background when displaying |
| the text in the active region (see the description of |
| <code class="code">enable-active-region</code> below). |
| This string must not take up any physical character positions on the display, |
| so it should consist only of terminal escape sequences. |
| It is output to the terminal before displaying the text in the active region. |
| This variable is reset to the default value whenever the terminal type changes. |
| The default value is the string that puts the terminal in standout mode, |
| as obtained from the terminal’s terminfo description. |
| A sample value might be ‘<samp class="samp">\e[01;33m</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-active_002dregion_002dend_002dcolor"></a><span><code class="code">active-region-end-color</code><a class="copiable-link" href="#index-active_002dregion_002dend_002dcolor"> ¶</a></span></dt> |
| <dd><p>A string variable that "undoes" the effects of <code class="code">active-region-start-color</code> |
| and restores "normal" terminal display appearance after displaying text |
| in the active region. |
| This string must not take up any physical character positions on the display, |
| so it should consist only of terminal escape sequences. |
| It is output to the terminal after displaying the text in the active region. |
| This variable is reset to the default value whenever the terminal type changes. |
| The default value is the string that restores the terminal from standout mode, |
| as obtained from the terminal’s terminfo description. |
| A sample value might be ‘<samp class="samp">\e[0m</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-bell_002dstyle"></a><span><code class="code">bell-style</code><a class="copiable-link" href="#index-bell_002dstyle"> ¶</a></span></dt> |
| <dd><p>Controls what happens when Readline wants to ring the terminal bell. |
| If set to ‘<samp class="samp">none</samp>’, Readline never rings the bell. If set to |
| ‘<samp class="samp">visible</samp>’, Readline uses a visible bell if one is available. |
| If set to ‘<samp class="samp">audible</samp>’ (the default), Readline attempts to ring |
| the terminal’s bell. |
| </p> |
| </dd> |
| <dt><a id="index-bind_002dtty_002dspecial_002dchars"></a><span><code class="code">bind-tty-special-chars</code><a class="copiable-link" href="#index-bind_002dtty_002dspecial_002dchars"> ¶</a></span></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’ (the default), Readline attempts to bind the control |
| characters treated specially by the kernel’s terminal driver to their |
| Readline equivalents. |
| </p> |
| </dd> |
| <dt><a id="index-blink_002dmatching_002dparen"></a><span><code class="code">blink-matching-paren</code><a class="copiable-link" href="#index-blink_002dmatching_002dparen"> ¶</a></span></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’, Readline attempts to briefly move the cursor to an |
| opening parenthesis when a closing parenthesis is inserted. The default |
| is ‘<samp class="samp">off</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-colored_002dcompletion_002dprefix"></a><span><code class="code">colored-completion-prefix</code><a class="copiable-link" href="#index-colored_002dcompletion_002dprefix"> ¶</a></span></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’, when listing completions, Readline displays the |
| common prefix of the set of possible completions using a different color. |
| The color definitions are taken from the value of the <code class="env">LS_COLORS</code> |
| environment variable. |
| If there is a color definition in <code class="env">LS_COLORS</code> for the custom suffix |
| ‘<samp class="samp">readline-colored-completion-prefix</samp>’, Readline uses this color for |
| the common prefix instead of its default. |
| The default is ‘<samp class="samp">off</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-colored_002dstats"></a><span><code class="code">colored-stats</code><a class="copiable-link" href="#index-colored_002dstats"> ¶</a></span></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’, Readline displays possible completions using different |
| colors to indicate their file type. |
| The color definitions are taken from the value of the <code class="env">LS_COLORS</code> |
| environment variable. |
| The default is ‘<samp class="samp">off</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-comment_002dbegin"></a><span><code class="code">comment-begin</code><a class="copiable-link" href="#index-comment_002dbegin"> ¶</a></span></dt> |
| <dd><p>The string to insert at the beginning of the line when the |
| <code class="code">insert-comment</code> command is executed. The default value |
| is <code class="code">"#"</code>. |
| </p> |
| </dd> |
| <dt><a id="index-completion_002ddisplay_002dwidth"></a><span><code class="code">completion-display-width</code><a class="copiable-link" href="#index-completion_002ddisplay_002dwidth"> ¶</a></span></dt> |
| <dd><p>The number of screen columns used to display possible matches |
| when performing completion. |
| The value is ignored if it is less than 0 or greater than the terminal |
| screen width. |
| A value of 0 will cause matches to be displayed one per line. |
| The default value is -1. |
| </p> |
| </dd> |
| <dt><a id="index-completion_002dignore_002dcase"></a><span><code class="code">completion-ignore-case</code><a class="copiable-link" href="#index-completion_002dignore_002dcase"> ¶</a></span></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’, Readline performs filename matching and completion |
| in a case-insensitive fashion. |
| The default value is ‘<samp class="samp">off</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-completion_002dmap_002dcase"></a><span><code class="code">completion-map-case</code><a class="copiable-link" href="#index-completion_002dmap_002dcase"> ¶</a></span></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’, and <var class="var">completion-ignore-case</var> is enabled, Readline |
| treats hyphens (‘<samp class="samp">-</samp>’) and underscores (‘<samp class="samp">_</samp>’) as equivalent when |
| performing case-insensitive filename matching and completion. |
| The default value is ‘<samp class="samp">off</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-completion_002dprefix_002ddisplay_002dlength"></a><span><code class="code">completion-prefix-display-length</code><a class="copiable-link" href="#index-completion_002dprefix_002ddisplay_002dlength"> ¶</a></span></dt> |
| <dd><p>The length in characters of the common prefix of a list of possible |
| completions that is displayed without modification. When set to a |
| value greater than zero, common prefixes longer than this value are |
| replaced with an ellipsis when displaying possible completions. |
| </p> |
| </dd> |
| <dt><a id="index-completion_002dquery_002ditems"></a><span><code class="code">completion-query-items</code><a class="copiable-link" href="#index-completion_002dquery_002ditems"> ¶</a></span></dt> |
| <dd><p>The number of possible completions that determines when the user is |
| asked whether the list of possibilities should be displayed. |
| If the number of possible completions is greater than or equal to this value, |
| Readline will ask whether or not the user wishes to view them; |
| otherwise, they are simply listed. |
| This variable must be set to an integer value greater than or equal to zero. |
| A zero value means Readline should never ask; negative values are |
| treated as zero. |
| The default limit is <code class="code">100</code>. |
| </p> |
| </dd> |
| <dt><a id="index-convert_002dmeta"></a><span><code class="code">convert-meta</code><a class="copiable-link" href="#index-convert_002dmeta"> ¶</a></span></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’, Readline will convert characters with the |
| eighth bit set to an <small class="sc">ASCII</small> key sequence by stripping the eighth |
| bit and prefixing an <kbd class="key">ESC</kbd> character, converting them to a |
| meta-prefixed key sequence. |
| The default value is ‘<samp class="samp">on</samp>’, but |
| will be set to ‘<samp class="samp">off</samp>’ if the locale is one that contains |
| eight-bit characters. |
| This variable is dependent on the <code class="code">LC_CTYPE</code> locale category, and |
| may change if the locale is changed. |
| </p> |
| </dd> |
| <dt><a id="index-disable_002dcompletion"></a><span><code class="code">disable-completion</code><a class="copiable-link" href="#index-disable_002dcompletion"> ¶</a></span></dt> |
| <dd><p>If set to ‘<samp class="samp">On</samp>’, Readline will inhibit word completion. |
| Completion characters will be inserted into the line as if they had |
| been mapped to <code class="code">self-insert</code>. The default is ‘<samp class="samp">off</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-echo_002dcontrol_002dcharacters"></a><span><code class="code">echo-control-characters</code><a class="copiable-link" href="#index-echo_002dcontrol_002dcharacters"> ¶</a></span></dt> |
| <dd><p>When set to ‘<samp class="samp">on</samp>’, on operating systems that indicate they support it, |
| Readline echoes a character corresponding to a signal generated from the |
| keyboard. The default is ‘<samp class="samp">on</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-editing_002dmode"></a><span><code class="code">editing-mode</code><a class="copiable-link" href="#index-editing_002dmode"> ¶</a></span></dt> |
| <dd><p>The <code class="code">editing-mode</code> variable controls which default set of |
| key bindings is used. By default, Readline starts up in Emacs editing |
| mode, where the keystrokes are most similar to Emacs. This variable can be |
| set to either ‘<samp class="samp">emacs</samp>’ or ‘<samp class="samp">vi</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-emacs_002dmode_002dstring"></a><span><code class="code">emacs-mode-string</code><a class="copiable-link" href="#index-emacs_002dmode_002dstring"> ¶</a></span></dt> |
| <dd><p>If the <var class="var">show-mode-in-prompt</var> variable is enabled, |
| this string is displayed immediately before the last line of the primary |
| prompt when emacs editing mode is active. The value is expanded like a |
| key binding, so the standard set of meta- and control prefixes and |
| backslash escape sequences is available. |
| Use the ‘<samp class="samp">\1</samp>’ and ‘<samp class="samp">\2</samp>’ escapes to begin and end sequences of |
| non-printing characters, which can be used to embed a terminal control |
| sequence into the mode string. |
| The default is ‘<samp class="samp">@</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-enable_002dactive_002dregion"></a><span><code class="code">enable-active-region</code><a class="copiable-link" href="#index-enable_002dactive_002dregion"> ¶</a></span></dt> |
| <dd><p>The <em class="dfn">point</em> is the current cursor position, and <em class="dfn">mark</em> refers |
| to a saved cursor position (see <a class="pxref" href="#Commands-For-Moving">Commands For Moving</a>). |
| The text between the point and mark is referred to as the <em class="dfn">region</em>. |
| When this variable is set to ‘<samp class="samp">On</samp>’, Readline allows certain commands |
| to designate the region as <em class="dfn">active</em>. |
| When the region is active, Readline highlights the text in the region using |
| the value of the <code class="code">active-region-start-color</code>, which defaults to the |
| string that enables |
| the terminal’s standout mode. |
| The active region shows the text inserted by bracketed-paste and any |
| matching text found by incremental and non-incremental history searches. |
| The default is ‘<samp class="samp">On</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-enable_002dbracketed_002dpaste"></a><span><code class="code">enable-bracketed-paste</code><a class="copiable-link" href="#index-enable_002dbracketed_002dpaste"> ¶</a></span></dt> |
| <dd><p>When set to ‘<samp class="samp">On</samp>’, Readline configures the terminal to insert each |
| paste into the editing buffer as a single string of characters, instead |
| of treating each character as if it had been read from the keyboard. |
| This is called putting the terminal into <em class="dfn">bracketed paste mode</em>; |
| it prevents Readline from executing any editing commands bound to key |
| sequences appearing in the pasted text. |
| The default is ‘<samp class="samp">On</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-enable_002dkeypad"></a><span><code class="code">enable-keypad</code><a class="copiable-link" href="#index-enable_002dkeypad"> ¶</a></span></dt> |
| <dd><p>When set to ‘<samp class="samp">on</samp>’, Readline will try to enable the application |
| keypad when it is called. Some systems need this to enable the |
| arrow keys. The default is ‘<samp class="samp">off</samp>’. |
| </p> |
| </dd> |
| <dt><code class="code">enable-meta-key</code></dt> |
| <dd><p>When set to ‘<samp class="samp">on</samp>’, Readline will try to enable any meta modifier |
| key the terminal claims to support when it is called. On many terminals, |
| the meta key is used to send eight-bit characters. |
| The default is ‘<samp class="samp">on</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-expand_002dtilde"></a><span><code class="code">expand-tilde</code><a class="copiable-link" href="#index-expand_002dtilde"> ¶</a></span></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’, tilde expansion is performed when Readline |
| attempts word completion. The default is ‘<samp class="samp">off</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-history_002dpreserve_002dpoint"></a><span><code class="code">history-preserve-point</code><a class="copiable-link" href="#index-history_002dpreserve_002dpoint"> ¶</a></span></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’, the history code attempts to place the point (the |
| current cursor position) at the |
| same location on each history line retrieved with <code class="code">previous-history</code> |
| or <code class="code">next-history</code>. The default is ‘<samp class="samp">off</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-history_002dsize"></a><span><code class="code">history-size</code><a class="copiable-link" href="#index-history_002dsize"> ¶</a></span></dt> |
| <dd><p>Set the maximum number of history entries saved in the history list. |
| If set to zero, any existing history entries are deleted and no new entries |
| are saved. |
| If set to a value less than zero, the number of history entries is not |
| limited. |
| By default, the number of history entries is not limited. |
| If an attempt is made to set <var class="var">history-size</var> to a non-numeric value, |
| the maximum number of history entries will be set to 500. |
| </p> |
| </dd> |
| <dt><a id="index-horizontal_002dscroll_002dmode"></a><span><code class="code">horizontal-scroll-mode</code><a class="copiable-link" href="#index-horizontal_002dscroll_002dmode"> ¶</a></span></dt> |
| <dd><p>This variable can be set to either ‘<samp class="samp">on</samp>’ or ‘<samp class="samp">off</samp>’. Setting it |
| to ‘<samp class="samp">on</samp>’ means that the text of the lines being edited will scroll |
| horizontally on a single screen line when they are longer than the width |
| of the screen, instead of wrapping onto a new screen line. |
| This variable is automatically set to ‘<samp class="samp">on</samp>’ for terminals of height 1. |
| By default, this variable is set to ‘<samp class="samp">off</samp>’. |
| </p> |
| </dd> |
| <dt><a class="index-entry-id" id="index-meta_002dflag"></a> |
| <a id="index-input_002dmeta"></a><span><code class="code">input-meta</code><a class="copiable-link" href="#index-input_002dmeta"> ¶</a></span></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’, Readline will enable eight-bit input (it |
| will not clear the eighth bit in the characters it reads), |
| regardless of what the terminal claims it can support. The |
| default value is ‘<samp class="samp">off</samp>’, but Readline will set it to ‘<samp class="samp">on</samp>’ if the |
| locale contains eight-bit characters. |
| The name <code class="code">meta-flag</code> is a synonym for this variable. |
| This variable is dependent on the <code class="code">LC_CTYPE</code> locale category, and |
| may change if the locale is changed. |
| </p> |
| </dd> |
| <dt><a id="index-isearch_002dterminators"></a><span><code class="code">isearch-terminators</code><a class="copiable-link" href="#index-isearch_002dterminators"> ¶</a></span></dt> |
| <dd><p>The string of characters that should terminate an incremental search without |
| subsequently executing the character as a command (see <a class="pxref" href="#Searching">Searching for Commands in the History</a>). |
| If this variable has not been given a value, the characters <kbd class="key">ESC</kbd> and |
| <kbd class="kbd">C-J</kbd> will terminate an incremental search. |
| </p> |
| </dd> |
| <dt><a id="index-keymap"></a><span><code class="code">keymap</code><a class="copiable-link" href="#index-keymap"> ¶</a></span></dt> |
| <dd><p>Sets Readline’s idea of the current keymap for key binding commands. |
| Built-in <code class="code">keymap</code> names are |
| <code class="code">emacs</code>, |
| <code class="code">emacs-standard</code>, |
| <code class="code">emacs-meta</code>, |
| <code class="code">emacs-ctlx</code>, |
| <code class="code">vi</code>, |
| <code class="code">vi-move</code>, |
| <code class="code">vi-command</code>, and |
| <code class="code">vi-insert</code>. |
| <code class="code">vi</code> is equivalent to <code class="code">vi-command</code> (<code class="code">vi-move</code> is also a |
| synonym); <code class="code">emacs</code> is equivalent to <code class="code">emacs-standard</code>. |
| Applications may add additional names. |
| The default value is <code class="code">emacs</code>. |
| The value of the <code class="code">editing-mode</code> variable also affects the |
| default keymap. |
| </p> |
| </dd> |
| <dt><code class="code">keyseq-timeout</code></dt> |
| <dd><p>Specifies the duration Readline will wait for a character when reading an |
| ambiguous key sequence (one that can form a complete key sequence using |
| the input read so far, or can take additional input to complete a longer |
| key sequence). |
| If no input is received within the timeout, Readline will use the shorter |
| but complete key sequence. |
| Readline uses this value to determine whether or not input is |
| available on the current input source (<code class="code">rl_instream</code> by default). |
| The value is specified in milliseconds, so a value of 1000 means that |
| Readline will wait one second for additional input. |
| If this variable is set to a value less than or equal to zero, or to a |
| non-numeric value, Readline will wait until another key is pressed to |
| decide which key sequence to complete. |
| The default value is <code class="code">500</code>. |
| </p> |
| </dd> |
| <dt><code class="code">mark-directories</code></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’, completed directory names have a slash |
| appended. The default is ‘<samp class="samp">on</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-mark_002dmodified_002dlines"></a><span><code class="code">mark-modified-lines</code><a class="copiable-link" href="#index-mark_002dmodified_002dlines"> ¶</a></span></dt> |
| <dd><p>This variable, when set to ‘<samp class="samp">on</samp>’, causes Readline to display an |
| asterisk (‘<samp class="samp">*</samp>’) at the start of history lines which have been modified. |
| This variable is ‘<samp class="samp">off</samp>’ by default. |
| </p> |
| </dd> |
| <dt><a id="index-mark_002dsymlinked_002ddirectories"></a><span><code class="code">mark-symlinked-directories</code><a class="copiable-link" href="#index-mark_002dsymlinked_002ddirectories"> ¶</a></span></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’, completed names which are symbolic links |
| to directories have a slash appended (subject to the value of |
| <code class="code">mark-directories</code>). |
| The default is ‘<samp class="samp">off</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-match_002dhidden_002dfiles"></a><span><code class="code">match-hidden-files</code><a class="copiable-link" href="#index-match_002dhidden_002dfiles"> ¶</a></span></dt> |
| <dd><p>This variable, when set to ‘<samp class="samp">on</samp>’, causes Readline to match files whose |
| names begin with a ‘<samp class="samp">.</samp>’ (hidden files) when performing filename |
| completion. |
| If set to ‘<samp class="samp">off</samp>’, the leading ‘<samp class="samp">.</samp>’ must be |
| supplied by the user in the filename to be completed. |
| This variable is ‘<samp class="samp">on</samp>’ by default. |
| </p> |
| </dd> |
| <dt><a id="index-menu_002dcomplete_002ddisplay_002dprefix"></a><span><code class="code">menu-complete-display-prefix</code><a class="copiable-link" href="#index-menu_002dcomplete_002ddisplay_002dprefix"> ¶</a></span></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’, menu completion displays the common prefix of the |
| list of possible completions (which may be empty) before cycling through |
| the list. The default is ‘<samp class="samp">off</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-output_002dmeta"></a><span><code class="code">output-meta</code><a class="copiable-link" href="#index-output_002dmeta"> ¶</a></span></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’, Readline will display characters with the |
| eighth bit set directly rather than as a meta-prefixed escape |
| sequence. |
| The default is ‘<samp class="samp">off</samp>’, but Readline will set it to ‘<samp class="samp">on</samp>’ if the |
| locale contains eight-bit characters. |
| This variable is dependent on the <code class="code">LC_CTYPE</code> locale category, and |
| may change if the locale is changed. |
| </p> |
| </dd> |
| <dt><a id="index-page_002dcompletions"></a><span><code class="code">page-completions</code><a class="copiable-link" href="#index-page_002dcompletions"> ¶</a></span></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’, Readline uses an internal <code class="code">more</code>-like pager |
| to display a screenful of possible completions at a time. |
| This variable is ‘<samp class="samp">on</samp>’ by default. |
| </p> |
| </dd> |
| <dt><code class="code">print-completions-horizontally</code></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’, Readline will display completions with matches |
| sorted horizontally in alphabetical order, rather than down the screen. |
| The default is ‘<samp class="samp">off</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-revert_002dall_002dat_002dnewline"></a><span><code class="code">revert-all-at-newline</code><a class="copiable-link" href="#index-revert_002dall_002dat_002dnewline"> ¶</a></span></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’, Readline will undo all changes to history lines |
| before returning when <code class="code">accept-line</code> is executed. By default, |
| history lines may be modified and retain individual undo lists across |
| calls to <code class="code">readline()</code>. The default is ‘<samp class="samp">off</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-show_002dall_002dif_002dambiguous"></a><span><code class="code">show-all-if-ambiguous</code><a class="copiable-link" href="#index-show_002dall_002dif_002dambiguous"> ¶</a></span></dt> |
| <dd><p>This alters the default behavior of the completion functions. If |
| set to ‘<samp class="samp">on</samp>’, |
| words which have more than one possible completion cause the |
| matches to be listed immediately instead of ringing the bell. |
| The default value is ‘<samp class="samp">off</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-show_002dall_002dif_002dunmodified"></a><span><code class="code">show-all-if-unmodified</code><a class="copiable-link" href="#index-show_002dall_002dif_002dunmodified"> ¶</a></span></dt> |
| <dd><p>This alters the default behavior of the completion functions in |
| a fashion similar to <var class="var">show-all-if-ambiguous</var>. |
| If set to ‘<samp class="samp">on</samp>’, |
| words which have more than one possible completion without any |
| possible partial completion (the possible completions don’t share |
| a common prefix) cause the matches to be listed immediately instead |
| of ringing the bell. |
| The default value is ‘<samp class="samp">off</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-show_002dmode_002din_002dprompt"></a><span><code class="code">show-mode-in-prompt</code><a class="copiable-link" href="#index-show_002dmode_002din_002dprompt"> ¶</a></span></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’, add a string to the beginning of the prompt |
| indicating the editing mode: emacs, vi command, or vi insertion. |
| The mode strings are user-settable (e.g., <var class="var">emacs-mode-string</var>). |
| The default value is ‘<samp class="samp">off</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-skip_002dcompleted_002dtext"></a><span><code class="code">skip-completed-text</code><a class="copiable-link" href="#index-skip_002dcompleted_002dtext"> ¶</a></span></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’, this alters the default completion behavior when |
| inserting a single match into the line. It’s only active when |
| performing completion in the middle of a word. If enabled, Readline |
| does not insert characters from the completion that match characters |
| after point in the word being completed, so portions of the word |
| following the cursor are not duplicated. |
| For instance, if this is enabled, attempting completion when the cursor |
| is after the ‘<samp class="samp">e</samp>’ in ‘<samp class="samp">Makefile</samp>’ will result in ‘<samp class="samp">Makefile</samp>’ |
| rather than ‘<samp class="samp">Makefilefile</samp>’, assuming there is a single possible |
| completion. |
| The default value is ‘<samp class="samp">off</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-vi_002dcmd_002dmode_002dstring"></a><span><code class="code">vi-cmd-mode-string</code><a class="copiable-link" href="#index-vi_002dcmd_002dmode_002dstring"> ¶</a></span></dt> |
| <dd><p>If the <var class="var">show-mode-in-prompt</var> variable is enabled, |
| this string is displayed immediately before the last line of the primary |
| prompt when vi editing mode is active and in command mode. |
| The value is expanded like a |
| key binding, so the standard set of meta- and control prefixes and |
| backslash escape sequences is available. |
| Use the ‘<samp class="samp">\1</samp>’ and ‘<samp class="samp">\2</samp>’ escapes to begin and end sequences of |
| non-printing characters, which can be used to embed a terminal control |
| sequence into the mode string. |
| The default is ‘<samp class="samp">(cmd)</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-vi_002dins_002dmode_002dstring"></a><span><code class="code">vi-ins-mode-string</code><a class="copiable-link" href="#index-vi_002dins_002dmode_002dstring"> ¶</a></span></dt> |
| <dd><p>If the <var class="var">show-mode-in-prompt</var> variable is enabled, |
| this string is displayed immediately before the last line of the primary |
| prompt when vi editing mode is active and in insertion mode. |
| The value is expanded like a |
| key binding, so the standard set of meta- and control prefixes and |
| backslash escape sequences is available. |
| Use the ‘<samp class="samp">\1</samp>’ and ‘<samp class="samp">\2</samp>’ escapes to begin and end sequences of |
| non-printing characters, which can be used to embed a terminal control |
| sequence into the mode string. |
| The default is ‘<samp class="samp">(ins)</samp>’. |
| </p> |
| </dd> |
| <dt><a id="index-visible_002dstats"></a><span><code class="code">visible-stats</code><a class="copiable-link" href="#index-visible_002dstats"> ¶</a></span></dt> |
| <dd><p>If set to ‘<samp class="samp">on</samp>’, a character denoting a file’s type |
| is appended to the filename when listing possible |
| completions. The default is ‘<samp class="samp">off</samp>’. |
| </p> |
| </dd> |
| </dl> |
| |
| </dd> |
| <dt>Key Bindings</dt> |
| <dd><p>The syntax for controlling key bindings in the init file is |
| simple. First you need to find the name of the command that you |
| want to change. The following sections contain tables of the command |
| name, the default keybinding, if any, and a short description of what |
| the command does. |
| </p> |
| <p>Once you know the name of the command, simply place on a line |
| in the init file the name of the key |
| you wish to bind the command to, a colon, and then the name of the |
| command. |
| There can be no space between the key name and the colon – that will be |
| interpreted as part of the key name. |
| The name of the key can be expressed in different ways, depending on |
| what you find most comfortable. |
| </p> |
| <p>In addition to command names, Readline allows keys to be bound |
| to a string that is inserted when the key is pressed (a <var class="var">macro</var>). |
| </p> |
| <p>The <code class="code">bind -p</code><!-- /@w --> command displays Readline function names and |
| bindings in a format that can be put directly into an initialization file. |
| See <a class="xref" href="#Bash-Builtins">Bash Builtin Commands</a>. |
| </p> |
| <dl class="table"> |
| <dt><var class="var">keyname</var>: <var class="var">function-name</var> or <var class="var">macro</var><!-- /@w --></dt> |
| <dd><p><var class="var">keyname</var> is the name of a key spelled out in English. For example: |
| </p><div class="example"> |
| <pre class="example-preformatted">Control-u: universal-argument |
| Meta-Rubout: backward-kill-word |
| Control-o: "> output" |
| </pre></div> |
| |
| <p>In the example above, <kbd class="kbd">C-u</kbd> is bound to the function |
| <code class="code">universal-argument</code>, |
| <kbd class="kbd">M-DEL</kbd> is bound to the function <code class="code">backward-kill-word</code>, and |
| <kbd class="kbd">C-o</kbd> is bound to run the macro |
| expressed on the right hand side (that is, to insert the text |
| ‘<samp class="samp">> output</samp>’ into the line). |
| </p> |
| <p>A number of symbolic character names are recognized while |
| processing this key binding syntax: |
| <var class="var">DEL</var>, |
| <var class="var">ESC</var>, |
| <var class="var">ESCAPE</var>, |
| <var class="var">LFD</var>, |
| <var class="var">NEWLINE</var>, |
| <var class="var">RET</var>, |
| <var class="var">RETURN</var>, |
| <var class="var">RUBOUT</var>, |
| <var class="var">SPACE</var>, |
| <var class="var">SPC</var>, |
| and |
| <var class="var">TAB</var>. |
| </p> |
| </dd> |
| <dt>"<var class="var">keyseq</var>": <var class="var">function-name</var> or <var class="var">macro</var><!-- /@w --></dt> |
| <dd><p><var class="var">keyseq</var> differs from <var class="var">keyname</var> above in that strings |
| denoting an entire key sequence can be specified, by placing |
| the key sequence in double quotes. Some <small class="sc">GNU</small> Emacs style key |
| escapes can be used, as in the following example, but the |
| special character names are not recognized. |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">"\C-u": universal-argument |
| "\C-x\C-r": re-read-init-file |
| "\e[11~": "Function Key 1" |
| </pre></div> |
| |
| <p>In the above example, <kbd class="kbd">C-u</kbd> is again bound to the function |
| <code class="code">universal-argument</code> (just as it was in the first example), |
| ‘<samp class="samp"><kbd class="kbd">C-x</kbd> <kbd class="kbd">C-r</kbd></samp>’ is bound to the function <code class="code">re-read-init-file</code>, |
| and ‘<samp class="samp"><kbd class="key">ESC</kbd> <kbd class="key">[</kbd> <kbd class="key">1</kbd> <kbd class="key">1</kbd> <kbd class="key">~</kbd></samp>’ is bound to insert |
| the text ‘<samp class="samp">Function Key 1</samp>’. |
| </p> |
| </dd> |
| </dl> |
| |
| <p>The following <small class="sc">GNU</small> Emacs style escape sequences are available when |
| specifying key sequences: |
| </p> |
| <dl class="table"> |
| <dt><code class="code"><kbd class="kbd">\C-</kbd></code></dt> |
| <dd><p>control prefix |
| </p></dd> |
| <dt><code class="code"><kbd class="kbd">\M-</kbd></code></dt> |
| <dd><p>meta prefix |
| </p></dd> |
| <dt><code class="code"><kbd class="kbd">\e</kbd></code></dt> |
| <dd><p>an escape character |
| </p></dd> |
| <dt><code class="code"><kbd class="kbd">\\</kbd></code></dt> |
| <dd><p>backslash |
| </p></dd> |
| <dt><code class="code"><kbd class="kbd">\"</kbd></code></dt> |
| <dd><p><kbd class="key">"</kbd>, a double quotation mark |
| </p></dd> |
| <dt><code class="code"><kbd class="kbd">\'</kbd></code></dt> |
| <dd><p><kbd class="key">'</kbd>, a single quote or apostrophe |
| </p></dd> |
| </dl> |
| |
| <p>In addition to the <small class="sc">GNU</small> Emacs style escape sequences, a second |
| set of backslash escapes is available: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">\a</code></dt> |
| <dd><p>alert (bell) |
| </p></dd> |
| <dt><code class="code">\b</code></dt> |
| <dd><p>backspace |
| </p></dd> |
| <dt><code class="code">\d</code></dt> |
| <dd><p>delete |
| </p></dd> |
| <dt><code class="code">\f</code></dt> |
| <dd><p>form feed |
| </p></dd> |
| <dt><code class="code">\n</code></dt> |
| <dd><p>newline |
| </p></dd> |
| <dt><code class="code">\r</code></dt> |
| <dd><p>carriage return |
| </p></dd> |
| <dt><code class="code">\t</code></dt> |
| <dd><p>horizontal tab |
| </p></dd> |
| <dt><code class="code">\v</code></dt> |
| <dd><p>vertical tab |
| </p></dd> |
| <dt><code class="code">\<var class="var">nnn</var></code></dt> |
| <dd><p>the eight-bit character whose value is the octal value <var class="var">nnn</var> |
| (one to three digits) |
| </p></dd> |
| <dt><code class="code">\x<var class="var">HH</var></code></dt> |
| <dd><p>the eight-bit character whose value is the hexadecimal value <var class="var">HH</var> |
| (one or two hex digits) |
| </p></dd> |
| </dl> |
| |
| <p>When entering the text of a macro, single or double quotes must |
| be used to indicate a macro definition. |
| Unquoted text is assumed to be a function name. |
| In the macro body, the backslash escapes described above are expanded. |
| Backslash will quote any other character in the macro text, |
| including ‘<samp class="samp">"</samp>’ and ‘<samp class="samp">'</samp>’. |
| For example, the following binding will make ‘<samp class="samp"><kbd class="kbd">C-x</kbd> \</samp>’ |
| insert a single ‘<samp class="samp">\</samp>’ into the line: |
| </p><div class="example"> |
| <pre class="example-preformatted">"\C-x\\": "\\" |
| </pre></div> |
| |
| </dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Conditional-Init-Constructs"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Sample-Init-File" accesskey="n" rel="next">Sample Init File</a>, Previous: <a href="#Readline-Init-File-Syntax" accesskey="p" rel="prev">Readline Init File Syntax</a>, Up: <a href="#Readline-Init-File" accesskey="u" rel="up">Readline Init File</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Conditional-Init-Constructs-1"><span>8.3.2 Conditional Init Constructs<a class="copiable-link" href="#Conditional-Init-Constructs-1"> ¶</a></span></h4> |
| |
| <p>Readline implements a facility similar in spirit to the conditional |
| compilation features of the C preprocessor which allows key |
| bindings and variable settings to be performed as the result |
| of tests. There are four parser directives used. |
| </p> |
| <dl class="table"> |
| <dt><code class="code">$if</code></dt> |
| <dd><p>The <code class="code">$if</code> construct allows bindings to be made based on the |
| editing mode, the terminal being used, or the application using |
| Readline. The text of the test, after any comparison operator, |
| extends to the end of the line; |
| unless otherwise noted, no characters are required to isolate it. |
| </p> |
| <dl class="table"> |
| <dt><code class="code">mode</code></dt> |
| <dd><p>The <code class="code">mode=</code> form of the <code class="code">$if</code> directive is used to test |
| whether Readline is in <code class="code">emacs</code> or <code class="code">vi</code> mode. |
| This may be used in conjunction |
| with the ‘<samp class="samp">set keymap</samp>’ command, for instance, to set bindings in |
| the <code class="code">emacs-standard</code> and <code class="code">emacs-ctlx</code> keymaps only if |
| Readline is starting out in <code class="code">emacs</code> mode. |
| </p> |
| </dd> |
| <dt><code class="code">term</code></dt> |
| <dd><p>The <code class="code">term=</code> form may be used to include terminal-specific |
| key bindings, perhaps to bind the key sequences output by the |
| terminal’s function keys. The word on the right side of the |
| ‘<samp class="samp">=</samp>’ is tested against both the full name of the terminal and |
| the portion of the terminal name before the first ‘<samp class="samp">-</samp>’. This |
| allows <code class="code">sun</code> to match both <code class="code">sun</code> and <code class="code">sun-cmd</code>, |
| for instance. |
| </p> |
| </dd> |
| <dt><code class="code">version</code></dt> |
| <dd><p>The <code class="code">version</code> test may be used to perform comparisons against |
| specific Readline versions. |
| The <code class="code">version</code> expands to the current Readline version. |
| The set of comparison operators includes |
| ‘<samp class="samp">=</samp>’ (and ‘<samp class="samp">==</samp>’), ‘<samp class="samp">!=</samp>’, ‘<samp class="samp"><=</samp>’, ‘<samp class="samp">>=</samp>’, ‘<samp class="samp"><</samp>’, |
| and ‘<samp class="samp">></samp>’. |
| The version number supplied on the right side of the operator consists |
| of a major version number, an optional decimal point, and an optional |
| minor version (e.g., ‘<samp class="samp">7.1</samp>’). If the minor version is omitted, it |
| is assumed to be ‘<samp class="samp">0</samp>’. |
| The operator may be separated from the string <code class="code">version</code> and |
| from the version number argument by whitespace. |
| The following example sets a variable if the Readline version being used |
| is 7.0 or newer: |
| </p><div class="example"> |
| <pre class="example-preformatted">$if version >= 7.0 |
| set show-mode-in-prompt on |
| $endif |
| </pre></div> |
| |
| </dd> |
| <dt><code class="code">application</code></dt> |
| <dd><p>The <var class="var">application</var> construct is used to include |
| application-specific settings. Each program using the Readline |
| library sets the <var class="var">application name</var>, and you can test for |
| a particular value. |
| This could be used to bind key sequences to functions useful for |
| a specific program. For instance, the following command adds a |
| key sequence that quotes the current or previous word in Bash: |
| </p><div class="example"> |
| <pre class="example-preformatted">$if Bash |
| # Quote the current or previous word |
| "\C-xq": "\eb\"\ef\"" |
| $endif |
| </pre></div> |
| |
| </dd> |
| <dt><code class="code">variable</code></dt> |
| <dd><p>The <var class="var">variable</var> construct provides simple equality tests for Readline |
| variables and values. |
| The permitted comparison operators are ‘<samp class="samp">=</samp>’, ‘<samp class="samp">==</samp>’, and ‘<samp class="samp">!=</samp>’. |
| The variable name must be separated from the comparison operator by |
| whitespace; the operator may be separated from the value on the right hand |
| side by whitespace. |
| Both string and boolean variables may be tested. Boolean variables must be |
| tested against the values <var class="var">on</var> and <var class="var">off</var>. |
| The following example is equivalent to the <code class="code">mode=emacs</code> test described |
| above: |
| </p><div class="example"> |
| <pre class="example-preformatted">$if editing-mode == emacs |
| set show-mode-in-prompt on |
| $endif |
| </pre></div> |
| </dd> |
| </dl> |
| |
| </dd> |
| <dt><code class="code">$endif</code></dt> |
| <dd><p>This command, as seen in the previous example, terminates an |
| <code class="code">$if</code> command. |
| </p> |
| </dd> |
| <dt><code class="code">$else</code></dt> |
| <dd><p>Commands in this branch of the <code class="code">$if</code> directive are executed if |
| the test fails. |
| </p> |
| </dd> |
| <dt><code class="code">$include</code></dt> |
| <dd><p>This directive takes a single filename as an argument and reads commands |
| and bindings from that file. |
| For example, the following directive reads from <samp class="file">/etc/inputrc</samp>: |
| </p><div class="example"> |
| <pre class="example-preformatted">$include /etc/inputrc |
| </pre></div> |
| </dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Sample-Init-File"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Conditional-Init-Constructs" accesskey="p" rel="prev">Conditional Init Constructs</a>, Up: <a href="#Readline-Init-File" accesskey="u" rel="up">Readline Init File</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Sample-Init-File-1"><span>8.3.3 Sample Init File<a class="copiable-link" href="#Sample-Init-File-1"> ¶</a></span></h4> |
| |
| <p>Here is an example of an <var class="var">inputrc</var> file. This illustrates key |
| binding, variable assignment, and conditional syntax. |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted"># This file controls the behaviour of line input editing for |
| # programs that use the GNU Readline library. Existing |
| # programs include FTP, Bash, and GDB. |
| # |
| # You can re-read the inputrc file with C-x C-r. |
| # Lines beginning with '#' are comments. |
| # |
| # First, include any system-wide bindings and variable |
| # assignments from /etc/Inputrc |
| $include /etc/Inputrc |
| |
| # |
| # Set various bindings for emacs mode. |
| |
| set editing-mode emacs |
| |
| $if mode=emacs |
| |
| Meta-Control-h: backward-kill-word Text after the function name is ignored |
| |
| # |
| # Arrow keys in keypad mode |
| # |
| #"\M-OD": backward-char |
| #"\M-OC": forward-char |
| #"\M-OA": previous-history |
| #"\M-OB": next-history |
| # |
| # Arrow keys in ANSI mode |
| # |
| "\M-[D": backward-char |
| "\M-[C": forward-char |
| "\M-[A": previous-history |
| "\M-[B": next-history |
| # |
| # Arrow keys in 8 bit keypad mode |
| # |
| #"\M-\C-OD": backward-char |
| #"\M-\C-OC": forward-char |
| #"\M-\C-OA": previous-history |
| #"\M-\C-OB": next-history |
| # |
| # Arrow keys in 8 bit ANSI mode |
| # |
| #"\M-\C-[D": backward-char |
| #"\M-\C-[C": forward-char |
| #"\M-\C-[A": previous-history |
| #"\M-\C-[B": next-history |
| |
| C-q: quoted-insert |
| |
| $endif |
| |
| # An old-style binding. This happens to be the default. |
| TAB: complete |
| |
| # Macros that are convenient for shell interaction |
| $if Bash |
| # edit the path |
| "\C-xp": "PATH=${PATH}\e\C-e\C-a\ef\C-f" |
| # prepare to type a quoted word -- |
| # insert open and close double quotes |
| # and move to just after the open quote |
| "\C-x\"": "\"\"\C-b" |
| # insert a backslash (testing backslash escapes |
| # in sequences and macros) |
| "\C-x\\": "\\" |
| # Quote the current or previous word |
| "\C-xq": "\eb\"\ef\"" |
| # Add a binding to refresh the line, which is unbound |
| "\C-xr": redraw-current-line |
| # Edit variable on current line. |
| "\M-\C-v": "\C-a\C-k$\C-y\M-\C-e\C-a\C-y=" |
| $endif |
| |
| # use a visible bell if one is available |
| set bell-style visible |
| |
| # don't strip characters to 7 bits when reading |
| set input-meta on |
| |
| # allow iso-latin1 characters to be inserted rather |
| # than converted to prefix-meta sequences |
| set convert-meta off |
| |
| # display characters with the eighth bit set directly |
| # rather than as meta-prefixed characters |
| set output-meta on |
| |
| # if there are 150 or more possible completions for a word, |
| # ask whether or not the user wants to see all of them |
| set completion-query-items 150 |
| |
| # For FTP |
| $if Ftp |
| "\C-xg": "get \M-?" |
| "\C-xt": "put \M-?" |
| "\M-.": yank-last-arg |
| $endif |
| </pre></div> |
| |
| <hr> |
| </div> |
| </div> |
| <div class="section-level-extent" id="Bindable-Readline-Commands"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Readline-vi-Mode" accesskey="n" rel="next">Readline vi Mode</a>, Previous: <a href="#Readline-Init-File" accesskey="p" rel="prev">Readline Init File</a>, Up: <a href="#Command-Line-Editing" accesskey="u" rel="up">Command Line Editing</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Bindable-Readline-Commands-1"><span>8.4 Bindable Readline Commands<a class="copiable-link" href="#Bindable-Readline-Commands-1"> ¶</a></span></h3> |
| |
| |
| <p>This section describes Readline commands that may be bound to key |
| sequences. |
| You can list your key bindings by executing |
| <code class="code">bind -P</code><!-- /@w --> or, for a more terse format, suitable for an |
| <var class="var">inputrc</var> file, <code class="code">bind -p</code><!-- /@w -->. (See <a class="xref" href="#Bash-Builtins">Bash Builtin Commands</a>.) |
| Command names without an accompanying key sequence are unbound by default. |
| </p> |
| <p>In the following descriptions, <em class="dfn">point</em> refers to the current cursor |
| position, and <em class="dfn">mark</em> refers to a cursor position saved by the |
| <code class="code">set-mark</code> command. |
| The text between the point and mark is referred to as the <em class="dfn">region</em>. |
| </p> |
| <ul class="mini-toc"> |
| <li><a href="#Commands-For-Moving" accesskey="1">Commands For Moving</a></li> |
| <li><a href="#Commands-For-History" accesskey="2">Commands For Manipulating The History</a></li> |
| <li><a href="#Commands-For-Text" accesskey="3">Commands For Changing Text</a></li> |
| <li><a href="#Commands-For-Killing" accesskey="4">Killing And Yanking</a></li> |
| <li><a href="#Numeric-Arguments" accesskey="5">Specifying Numeric Arguments</a></li> |
| <li><a href="#Commands-For-Completion" accesskey="6">Letting Readline Type For You</a></li> |
| <li><a href="#Keyboard-Macros" accesskey="7">Keyboard Macros</a></li> |
| <li><a href="#Miscellaneous-Commands" accesskey="8">Some Miscellaneous Commands</a></li> |
| </ul> |
| <hr> |
| <div class="subsection-level-extent" id="Commands-For-Moving"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Commands-For-History" accesskey="n" rel="next">Commands For Manipulating The History</a>, Up: <a href="#Bindable-Readline-Commands" accesskey="u" rel="up">Bindable Readline Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Commands-For-Moving-1"><span>8.4.1 Commands For Moving<a class="copiable-link" href="#Commands-For-Moving-1"> ¶</a></span></h4> |
| <dl class="ftable"> |
| <dt><a id="index-beginning_002dof_002dline-_0028C_002da_0029"></a><span><code class="code">beginning-of-line (C-a)</code><a class="copiable-link" href="#index-beginning_002dof_002dline-_0028C_002da_0029"> ¶</a></span></dt> |
| <dd><p>Move to the start of the current line. |
| </p> |
| </dd> |
| <dt><a id="index-end_002dof_002dline-_0028C_002de_0029"></a><span><code class="code">end-of-line (C-e)</code><a class="copiable-link" href="#index-end_002dof_002dline-_0028C_002de_0029"> ¶</a></span></dt> |
| <dd><p>Move to the end of the line. |
| </p> |
| </dd> |
| <dt><a id="index-forward_002dchar-_0028C_002df_0029"></a><span><code class="code">forward-char (C-f)</code><a class="copiable-link" href="#index-forward_002dchar-_0028C_002df_0029"> ¶</a></span></dt> |
| <dd><p>Move forward a character. |
| </p> |
| </dd> |
| <dt><a id="index-backward_002dchar-_0028C_002db_0029"></a><span><code class="code">backward-char (C-b)</code><a class="copiable-link" href="#index-backward_002dchar-_0028C_002db_0029"> ¶</a></span></dt> |
| <dd><p>Move back a character. |
| </p> |
| </dd> |
| <dt><a id="index-forward_002dword-_0028M_002df_0029"></a><span><code class="code">forward-word (M-f)</code><a class="copiable-link" href="#index-forward_002dword-_0028M_002df_0029"> ¶</a></span></dt> |
| <dd><p>Move forward to the end of the next word. |
| Words are composed of letters and digits. |
| </p> |
| </dd> |
| <dt><a id="index-backward_002dword-_0028M_002db_0029"></a><span><code class="code">backward-word (M-b)</code><a class="copiable-link" href="#index-backward_002dword-_0028M_002db_0029"> ¶</a></span></dt> |
| <dd><p>Move back to the start of the current or previous word. |
| Words are composed of letters and digits. |
| </p> |
| </dd> |
| <dt><a id="index-shell_002dforward_002dword-_0028M_002dC_002df_0029"></a><span><code class="code">shell-forward-word (M-C-f)</code><a class="copiable-link" href="#index-shell_002dforward_002dword-_0028M_002dC_002df_0029"> ¶</a></span></dt> |
| <dd><p>Move forward to the end of the next word. |
| Words are delimited by non-quoted shell metacharacters. |
| </p> |
| </dd> |
| <dt><a id="index-shell_002dbackward_002dword-_0028M_002dC_002db_0029"></a><span><code class="code">shell-backward-word (M-C-b)</code><a class="copiable-link" href="#index-shell_002dbackward_002dword-_0028M_002dC_002db_0029"> ¶</a></span></dt> |
| <dd><p>Move back to the start of the current or previous word. |
| Words are delimited by non-quoted shell metacharacters. |
| </p> |
| </dd> |
| <dt><a id="index-previous_002dscreen_002dline-_0028_0029"></a><span><code class="code">previous-screen-line ()</code><a class="copiable-link" href="#index-previous_002dscreen_002dline-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Attempt to move point to the same physical screen column on the previous |
| physical screen line. This will not have the desired effect if the current |
| Readline line does not take up more than one physical line or if point is not |
| greater than the length of the prompt plus the screen width. |
| </p> |
| </dd> |
| <dt><a id="index-next_002dscreen_002dline-_0028_0029"></a><span><code class="code">next-screen-line ()</code><a class="copiable-link" href="#index-next_002dscreen_002dline-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Attempt to move point to the same physical screen column on the next |
| physical screen line. This will not have the desired effect if the current |
| Readline line does not take up more than one physical line or if the length |
| of the current Readline line is not greater than the length of the prompt |
| plus the screen width. |
| </p> |
| </dd> |
| <dt><a id="index-clear_002ddisplay-_0028M_002dC_002dl_0029"></a><span><code class="code">clear-display (M-C-l)</code><a class="copiable-link" href="#index-clear_002ddisplay-_0028M_002dC_002dl_0029"> ¶</a></span></dt> |
| <dd><p>Clear the screen and, if possible, the terminal’s scrollback buffer, |
| then redraw the current line, |
| leaving the current line at the top of the screen. |
| </p> |
| </dd> |
| <dt><a id="index-clear_002dscreen-_0028C_002dl_0029"></a><span><code class="code">clear-screen (C-l)</code><a class="copiable-link" href="#index-clear_002dscreen-_0028C_002dl_0029"> ¶</a></span></dt> |
| <dd><p>Clear the screen, |
| then redraw the current line, |
| leaving the current line at the top of the screen. |
| </p> |
| </dd> |
| <dt><a id="index-redraw_002dcurrent_002dline-_0028_0029"></a><span><code class="code">redraw-current-line ()</code><a class="copiable-link" href="#index-redraw_002dcurrent_002dline-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Refresh the current line. By default, this is unbound. |
| </p> |
| </dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Commands-For-History"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Commands-For-Text" accesskey="n" rel="next">Commands For Changing Text</a>, Previous: <a href="#Commands-For-Moving" accesskey="p" rel="prev">Commands For Moving</a>, Up: <a href="#Bindable-Readline-Commands" accesskey="u" rel="up">Bindable Readline Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Commands-For-Manipulating-The-History"><span>8.4.2 Commands For Manipulating The History<a class="copiable-link" href="#Commands-For-Manipulating-The-History"> ¶</a></span></h4> |
| |
| <dl class="ftable"> |
| <dt><a id="index-accept_002dline-_0028Newline-or-Return_0029"></a><span><code class="code">accept-line (Newline or Return)</code><a class="copiable-link" href="#index-accept_002dline-_0028Newline-or-Return_0029"> ¶</a></span></dt> |
| <dd><p>Accept the line regardless of where the cursor is. |
| If this line is |
| non-empty, add it to the history list according to the setting of |
| the <code class="env">HISTCONTROL</code> and <code class="env">HISTIGNORE</code> variables. |
| If this line is a modified history line, then restore the history line |
| to its original state. |
| </p> |
| </dd> |
| <dt><a id="index-previous_002dhistory-_0028C_002dp_0029"></a><span><code class="code">previous-history (C-p)</code><a class="copiable-link" href="#index-previous_002dhistory-_0028C_002dp_0029"> ¶</a></span></dt> |
| <dd><p>Move ‘back’ through the history list, fetching the previous command. |
| </p> |
| </dd> |
| <dt><a id="index-next_002dhistory-_0028C_002dn_0029"></a><span><code class="code">next-history (C-n)</code><a class="copiable-link" href="#index-next_002dhistory-_0028C_002dn_0029"> ¶</a></span></dt> |
| <dd><p>Move ‘forward’ through the history list, fetching the next command. |
| </p> |
| </dd> |
| <dt><a id="index-beginning_002dof_002dhistory-_0028M_002d_003c_0029"></a><span><code class="code">beginning-of-history (M-<)</code><a class="copiable-link" href="#index-beginning_002dof_002dhistory-_0028M_002d_003c_0029"> ¶</a></span></dt> |
| <dd><p>Move to the first line in the history. |
| </p> |
| </dd> |
| <dt><a id="index-end_002dof_002dhistory-_0028M_002d_003e_0029"></a><span><code class="code">end-of-history (M->)</code><a class="copiable-link" href="#index-end_002dof_002dhistory-_0028M_002d_003e_0029"> ¶</a></span></dt> |
| <dd><p>Move to the end of the input history, i.e., the line currently |
| being entered. |
| </p> |
| </dd> |
| <dt><a id="index-reverse_002dsearch_002dhistory-_0028C_002dr_0029"></a><span><code class="code">reverse-search-history (C-r)</code><a class="copiable-link" href="#index-reverse_002dsearch_002dhistory-_0028C_002dr_0029"> ¶</a></span></dt> |
| <dd><p>Search backward starting at the current line and moving ‘up’ through |
| the history as necessary. This is an incremental search. |
| This command sets the region to the matched text and activates the mark. |
| </p> |
| </dd> |
| <dt><a id="index-forward_002dsearch_002dhistory-_0028C_002ds_0029"></a><span><code class="code">forward-search-history (C-s)</code><a class="copiable-link" href="#index-forward_002dsearch_002dhistory-_0028C_002ds_0029"> ¶</a></span></dt> |
| <dd><p>Search forward starting at the current line and moving ‘down’ through |
| the history as necessary. This is an incremental search. |
| This command sets the region to the matched text and activates the mark. |
| </p> |
| </dd> |
| <dt><a id="index-non_002dincremental_002dreverse_002dsearch_002dhistory-_0028M_002dp_0029"></a><span><code class="code">non-incremental-reverse-search-history (M-p)</code><a class="copiable-link" href="#index-non_002dincremental_002dreverse_002dsearch_002dhistory-_0028M_002dp_0029"> ¶</a></span></dt> |
| <dd><p>Search backward starting at the current line and moving ‘up’ |
| through the history as necessary using a non-incremental search |
| for a string supplied by the user. |
| The search string may match anywhere in a history line. |
| </p> |
| </dd> |
| <dt><a id="index-non_002dincremental_002dforward_002dsearch_002dhistory-_0028M_002dn_0029"></a><span><code class="code">non-incremental-forward-search-history (M-n)</code><a class="copiable-link" href="#index-non_002dincremental_002dforward_002dsearch_002dhistory-_0028M_002dn_0029"> ¶</a></span></dt> |
| <dd><p>Search forward starting at the current line and moving ‘down’ |
| through the history as necessary using a non-incremental search |
| for a string supplied by the user. |
| The search string may match anywhere in a history line. |
| </p> |
| </dd> |
| <dt><a id="index-history_002dsearch_002dforward-_0028_0029"></a><span><code class="code">history-search-forward ()</code><a class="copiable-link" href="#index-history_002dsearch_002dforward-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Search forward through the history for the string of characters |
| between the start of the current line and the point. |
| The search string must match at the beginning of a history line. |
| This is a non-incremental search. |
| By default, this command is unbound. |
| </p> |
| </dd> |
| <dt><a id="index-history_002dsearch_002dbackward-_0028_0029"></a><span><code class="code">history-search-backward ()</code><a class="copiable-link" href="#index-history_002dsearch_002dbackward-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Search backward through the history for the string of characters |
| between the start of the current line and the point. |
| The search string must match at the beginning of a history line. |
| This is a non-incremental search. |
| By default, this command is unbound. |
| </p> |
| </dd> |
| <dt><a id="index-history_002dsubstring_002dsearch_002dforward-_0028_0029"></a><span><code class="code">history-substring-search-forward ()</code><a class="copiable-link" href="#index-history_002dsubstring_002dsearch_002dforward-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Search forward through the history for the string of characters |
| between the start of the current line and the point. |
| The search string may match anywhere in a history line. |
| This is a non-incremental search. |
| By default, this command is unbound. |
| </p> |
| </dd> |
| <dt><a id="index-history_002dsubstring_002dsearch_002dbackward-_0028_0029"></a><span><code class="code">history-substring-search-backward ()</code><a class="copiable-link" href="#index-history_002dsubstring_002dsearch_002dbackward-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Search backward through the history for the string of characters |
| between the start of the current line and the point. |
| The search string may match anywhere in a history line. |
| This is a non-incremental search. |
| By default, this command is unbound. |
| </p> |
| </dd> |
| <dt><a id="index-yank_002dnth_002darg-_0028M_002dC_002dy_0029"></a><span><code class="code">yank-nth-arg (M-C-y)</code><a class="copiable-link" href="#index-yank_002dnth_002darg-_0028M_002dC_002dy_0029"> ¶</a></span></dt> |
| <dd><p>Insert the first argument to the previous command (usually |
| the second word on the previous line) at point. |
| With an argument <var class="var">n</var>, |
| insert the <var class="var">n</var>th word from the previous command (the words |
| in the previous command begin with word 0). A negative argument |
| inserts the <var class="var">n</var>th word from the end of the previous command. |
| Once the argument <var class="var">n</var> is computed, the argument is extracted |
| as if the ‘<samp class="samp">!<var class="var">n</var></samp>’ history expansion had been specified. |
| </p> |
| </dd> |
| <dt><a id="index-yank_002dlast_002darg-_0028M_002d_002e-or-M_002d_005f_0029"></a><span><code class="code">yank-last-arg (M-. or M-_)</code><a class="copiable-link" href="#index-yank_002dlast_002darg-_0028M_002d_002e-or-M_002d_005f_0029"> ¶</a></span></dt> |
| <dd><p>Insert last argument to the previous command (the last word of the |
| previous history entry). |
| With a numeric argument, behave exactly like <code class="code">yank-nth-arg</code>. |
| Successive calls to <code class="code">yank-last-arg</code> move back through the history |
| list, inserting the last word (or the word specified by the argument to |
| the first call) of each line in turn. |
| Any numeric argument supplied to these successive calls determines |
| the direction to move through the history. A negative argument switches |
| the direction through the history (back or forward). |
| The history expansion facilities are used to extract the last argument, |
| as if the ‘<samp class="samp">!$</samp>’ history expansion had been specified. |
| </p> |
| </dd> |
| <dt><a id="index-operate_002dand_002dget_002dnext-_0028C_002do_0029"></a><span><code class="code">operate-and-get-next (C-o)</code><a class="copiable-link" href="#index-operate_002dand_002dget_002dnext-_0028C_002do_0029"> ¶</a></span></dt> |
| <dd><p>Accept the current line for return to the calling application as if a |
| newline had been entered, |
| and fetch the next line relative to the current line from the history |
| for editing. |
| A numeric argument, if supplied, specifies the history entry to use instead |
| of the current line. |
| </p> |
| </dd> |
| <dt><a id="index-fetch_002dhistory-_0028_0029"></a><span><code class="code">fetch-history ()</code><a class="copiable-link" href="#index-fetch_002dhistory-_0028_0029"> ¶</a></span></dt> |
| <dd><p>With a numeric argument, fetch that entry from the history list |
| and make it the current line. |
| Without an argument, move back to the first entry in the history list. |
| </p> |
| </dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Commands-For-Text"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Commands-For-Killing" accesskey="n" rel="next">Killing And Yanking</a>, Previous: <a href="#Commands-For-History" accesskey="p" rel="prev">Commands For Manipulating The History</a>, Up: <a href="#Bindable-Readline-Commands" accesskey="u" rel="up">Bindable Readline Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Commands-For-Changing-Text"><span>8.4.3 Commands For Changing Text<a class="copiable-link" href="#Commands-For-Changing-Text"> ¶</a></span></h4> |
| |
| <dl class="ftable"> |
| <dt><a id="index-end_002dof_002dfile-_0028usually-C_002dd_0029"></a><span><code class="code"><i class="i">end-of-file</i> (usually C-d)</code><a class="copiable-link" href="#index-end_002dof_002dfile-_0028usually-C_002dd_0029"> ¶</a></span></dt> |
| <dd><p>The character indicating end-of-file as set, for example, by |
| <code class="code">stty</code>. If this character is read when there are no characters |
| on the line, and point is at the beginning of the line, Readline |
| interprets it as the end of input and returns <small class="sc">EOF</small>. |
| </p> |
| </dd> |
| <dt><a id="index-delete_002dchar-_0028C_002dd_0029"></a><span><code class="code">delete-char (C-d)</code><a class="copiable-link" href="#index-delete_002dchar-_0028C_002dd_0029"> ¶</a></span></dt> |
| <dd><p>Delete the character at point. If this function is bound to the |
| same character as the tty <small class="sc">EOF</small> character, as <kbd class="kbd">C-d</kbd> |
| commonly is, see above for the effects. |
| </p> |
| </dd> |
| <dt><a id="index-backward_002ddelete_002dchar-_0028Rubout_0029"></a><span><code class="code">backward-delete-char (Rubout)</code><a class="copiable-link" href="#index-backward_002ddelete_002dchar-_0028Rubout_0029"> ¶</a></span></dt> |
| <dd><p>Delete the character behind the cursor. A numeric argument means |
| to kill the characters instead of deleting them. |
| </p> |
| </dd> |
| <dt><a id="index-forward_002dbackward_002ddelete_002dchar-_0028_0029"></a><span><code class="code">forward-backward-delete-char ()</code><a class="copiable-link" href="#index-forward_002dbackward_002ddelete_002dchar-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Delete the character under the cursor, unless the cursor is at the |
| end of the line, in which case the character behind the cursor is |
| deleted. By default, this is not bound to a key. |
| </p> |
| </dd> |
| <dt><a id="index-quoted_002dinsert-_0028C_002dq-or-C_002dv_0029"></a><span><code class="code">quoted-insert (C-q or C-v)</code><a class="copiable-link" href="#index-quoted_002dinsert-_0028C_002dq-or-C_002dv_0029"> ¶</a></span></dt> |
| <dd><p>Add the next character typed to the line verbatim. This is |
| how to insert key sequences like <kbd class="kbd">C-q</kbd>, for example. |
| </p> |
| |
| </dd> |
| <dt><a id="index-self_002dinsert-_0028a_002c-b_002c-A_002c-1_002c-_0021_002c-_2026_0029"></a><span><code class="code">self-insert (a, b, A, 1, !, …)</code><a class="copiable-link" href="#index-self_002dinsert-_0028a_002c-b_002c-A_002c-1_002c-_0021_002c-_2026_0029"> ¶</a></span></dt> |
| <dd><p>Insert yourself. |
| </p> |
| </dd> |
| <dt><a id="index-bracketed_002dpaste_002dbegin-_0028_0029"></a><span><code class="code">bracketed-paste-begin ()</code><a class="copiable-link" href="#index-bracketed_002dpaste_002dbegin-_0028_0029"> ¶</a></span></dt> |
| <dd><p>This function is intended to be bound to the "bracketed paste" escape |
| sequence sent by some terminals, and such a binding is assigned by default. |
| It allows Readline to insert the pasted text as a single unit without treating |
| each character as if it had been read from the keyboard. The characters |
| are inserted as if each one was bound to <code class="code">self-insert</code> instead of |
| executing any editing commands. |
| </p> |
| <p>Bracketed paste sets the region (the characters between point and the mark) |
| to the inserted text. It uses the concept of an <em class="emph">active mark</em>: when the |
| mark is active, Readline redisplay uses the terminal’s standout mode to |
| denote the region. |
| </p> |
| </dd> |
| <dt><a id="index-transpose_002dchars-_0028C_002dt_0029"></a><span><code class="code">transpose-chars (C-t)</code><a class="copiable-link" href="#index-transpose_002dchars-_0028C_002dt_0029"> ¶</a></span></dt> |
| <dd><p>Drag the character before the cursor forward over |
| the character at the cursor, moving the |
| cursor forward as well. If the insertion point |
| is at the end of the line, then this |
| transposes the last two characters of the line. |
| Negative arguments have no effect. |
| </p> |
| </dd> |
| <dt><a id="index-transpose_002dwords-_0028M_002dt_0029"></a><span><code class="code">transpose-words (M-t)</code><a class="copiable-link" href="#index-transpose_002dwords-_0028M_002dt_0029"> ¶</a></span></dt> |
| <dd><p>Drag the word before point past the word after point, |
| moving point past that word as well. |
| If the insertion point is at the end of the line, this transposes |
| the last two words on the line. |
| </p> |
| </dd> |
| <dt><a id="index-upcase_002dword-_0028M_002du_0029"></a><span><code class="code">upcase-word (M-u)</code><a class="copiable-link" href="#index-upcase_002dword-_0028M_002du_0029"> ¶</a></span></dt> |
| <dd><p>Uppercase the current (or following) word. With a negative argument, |
| uppercase the previous word, but do not move the cursor. |
| </p> |
| </dd> |
| <dt><a id="index-downcase_002dword-_0028M_002dl_0029"></a><span><code class="code">downcase-word (M-l)</code><a class="copiable-link" href="#index-downcase_002dword-_0028M_002dl_0029"> ¶</a></span></dt> |
| <dd><p>Lowercase the current (or following) word. With a negative argument, |
| lowercase the previous word, but do not move the cursor. |
| </p> |
| </dd> |
| <dt><a id="index-capitalize_002dword-_0028M_002dc_0029"></a><span><code class="code">capitalize-word (M-c)</code><a class="copiable-link" href="#index-capitalize_002dword-_0028M_002dc_0029"> ¶</a></span></dt> |
| <dd><p>Capitalize the current (or following) word. With a negative argument, |
| capitalize the previous word, but do not move the cursor. |
| </p> |
| </dd> |
| <dt><a id="index-overwrite_002dmode-_0028_0029"></a><span><code class="code">overwrite-mode ()</code><a class="copiable-link" href="#index-overwrite_002dmode-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Toggle overwrite mode. With an explicit positive numeric argument, |
| switches to overwrite mode. With an explicit non-positive numeric |
| argument, switches to insert mode. This command affects only |
| <code class="code">emacs</code> mode; <code class="code">vi</code> mode does overwrite differently. |
| Each call to <code class="code">readline()</code> starts in insert mode. |
| </p> |
| <p>In overwrite mode, characters bound to <code class="code">self-insert</code> replace |
| the text at point rather than pushing the text to the right. |
| Characters bound to <code class="code">backward-delete-char</code> replace the character |
| before point with a space. |
| </p> |
| <p>By default, this command is unbound. |
| </p> |
| </dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Commands-For-Killing"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Numeric-Arguments" accesskey="n" rel="next">Specifying Numeric Arguments</a>, Previous: <a href="#Commands-For-Text" accesskey="p" rel="prev">Commands For Changing Text</a>, Up: <a href="#Bindable-Readline-Commands" accesskey="u" rel="up">Bindable Readline Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Killing-And-Yanking"><span>8.4.4 Killing And Yanking<a class="copiable-link" href="#Killing-And-Yanking"> ¶</a></span></h4> |
| |
| <dl class="ftable"> |
| <dt><a id="index-kill_002dline-_0028C_002dk_0029"></a><span><code class="code">kill-line (C-k)</code><a class="copiable-link" href="#index-kill_002dline-_0028C_002dk_0029"> ¶</a></span></dt> |
| <dd><p>Kill the text from point to the end of the line. |
| With a negative numeric argument, kill backward from the cursor to the |
| beginning of the current line. |
| </p> |
| </dd> |
| <dt><a id="index-backward_002dkill_002dline-_0028C_002dx-Rubout_0029"></a><span><code class="code">backward-kill-line (C-x Rubout)</code><a class="copiable-link" href="#index-backward_002dkill_002dline-_0028C_002dx-Rubout_0029"> ¶</a></span></dt> |
| <dd><p>Kill backward from the cursor to the beginning of the current line. |
| With a negative numeric argument, kill forward from the cursor to the |
| end of the current line. |
| </p> |
| </dd> |
| <dt><a id="index-unix_002dline_002ddiscard-_0028C_002du_0029"></a><span><code class="code">unix-line-discard (C-u)</code><a class="copiable-link" href="#index-unix_002dline_002ddiscard-_0028C_002du_0029"> ¶</a></span></dt> |
| <dd><p>Kill backward from the cursor to the beginning of the current line. |
| </p> |
| </dd> |
| <dt><a id="index-kill_002dwhole_002dline-_0028_0029"></a><span><code class="code">kill-whole-line ()</code><a class="copiable-link" href="#index-kill_002dwhole_002dline-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Kill all characters on the current line, no matter where point is. |
| By default, this is unbound. |
| </p> |
| </dd> |
| <dt><a id="index-kill_002dword-_0028M_002dd_0029"></a><span><code class="code">kill-word (M-d)</code><a class="copiable-link" href="#index-kill_002dword-_0028M_002dd_0029"> ¶</a></span></dt> |
| <dd><p>Kill from point to the end of the current word, or if between |
| words, to the end of the next word. |
| Word boundaries are the same as <code class="code">forward-word</code>. |
| </p> |
| </dd> |
| <dt><a id="index-backward_002dkill_002dword-_0028M_002dDEL_0029"></a><span><code class="code">backward-kill-word (M-<kbd class="key">DEL</kbd>)</code><a class="copiable-link" href="#index-backward_002dkill_002dword-_0028M_002dDEL_0029"> ¶</a></span></dt> |
| <dd><p>Kill the word behind point. |
| Word boundaries are the same as <code class="code">backward-word</code>. |
| </p> |
| </dd> |
| <dt><a id="index-shell_002dkill_002dword-_0028M_002dC_002dd_0029"></a><span><code class="code">shell-kill-word (M-C-d)</code><a class="copiable-link" href="#index-shell_002dkill_002dword-_0028M_002dC_002dd_0029"> ¶</a></span></dt> |
| <dd><p>Kill from point to the end of the current word, or if between |
| words, to the end of the next word. |
| Word boundaries are the same as <code class="code">shell-forward-word</code>. |
| </p> |
| </dd> |
| <dt><a id="index-shell_002dbackward_002dkill_002dword-_0028_0029"></a><span><code class="code">shell-backward-kill-word ()</code><a class="copiable-link" href="#index-shell_002dbackward_002dkill_002dword-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Kill the word behind point. |
| Word boundaries are the same as <code class="code">shell-backward-word</code>. |
| </p> |
| </dd> |
| <dt><a id="index-shell_002dtranspose_002dwords-_0028M_002dC_002dt_0029"></a><span><code class="code">shell-transpose-words (M-C-t)</code><a class="copiable-link" href="#index-shell_002dtranspose_002dwords-_0028M_002dC_002dt_0029"> ¶</a></span></dt> |
| <dd><p>Drag the word before point past the word after point, |
| moving point past that word as well. |
| If the insertion point is at the end of the line, this transposes |
| the last two words on the line. |
| Word boundaries are the same as <code class="code">shell-forward-word</code> and |
| <code class="code">shell-backward-word</code>. |
| </p> |
| </dd> |
| <dt><a id="index-unix_002dword_002drubout-_0028C_002dw_0029"></a><span><code class="code">unix-word-rubout (C-w)</code><a class="copiable-link" href="#index-unix_002dword_002drubout-_0028C_002dw_0029"> ¶</a></span></dt> |
| <dd><p>Kill the word behind point, using white space as a word boundary. |
| The killed text is saved on the kill-ring. |
| </p> |
| </dd> |
| <dt><a id="index-unix_002dfilename_002drubout-_0028_0029"></a><span><code class="code">unix-filename-rubout ()</code><a class="copiable-link" href="#index-unix_002dfilename_002drubout-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Kill the word behind point, using white space and the slash character |
| as the word boundaries. |
| The killed text is saved on the kill-ring. |
| </p> |
| </dd> |
| <dt><a id="index-delete_002dhorizontal_002dspace-_0028_0029"></a><span><code class="code">delete-horizontal-space ()</code><a class="copiable-link" href="#index-delete_002dhorizontal_002dspace-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Delete all spaces and tabs around point. By default, this is unbound. |
| </p> |
| </dd> |
| <dt><a id="index-kill_002dregion-_0028_0029"></a><span><code class="code">kill-region ()</code><a class="copiable-link" href="#index-kill_002dregion-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Kill the text in the current region. |
| By default, this command is unbound. |
| </p> |
| </dd> |
| <dt><a id="index-copy_002dregion_002das_002dkill-_0028_0029"></a><span><code class="code">copy-region-as-kill ()</code><a class="copiable-link" href="#index-copy_002dregion_002das_002dkill-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Copy the text in the region to the kill buffer, so it can be yanked |
| right away. By default, this command is unbound. |
| </p> |
| </dd> |
| <dt><a id="index-copy_002dbackward_002dword-_0028_0029"></a><span><code class="code">copy-backward-word ()</code><a class="copiable-link" href="#index-copy_002dbackward_002dword-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Copy the word before point to the kill buffer. |
| The word boundaries are the same as <code class="code">backward-word</code>. |
| By default, this command is unbound. |
| </p> |
| </dd> |
| <dt><a id="index-copy_002dforward_002dword-_0028_0029"></a><span><code class="code">copy-forward-word ()</code><a class="copiable-link" href="#index-copy_002dforward_002dword-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Copy the word following point to the kill buffer. |
| The word boundaries are the same as <code class="code">forward-word</code>. |
| By default, this command is unbound. |
| </p> |
| </dd> |
| <dt><a id="index-yank-_0028C_002dy_0029"></a><span><code class="code">yank (C-y)</code><a class="copiable-link" href="#index-yank-_0028C_002dy_0029"> ¶</a></span></dt> |
| <dd><p>Yank the top of the kill ring into the buffer at point. |
| </p> |
| </dd> |
| <dt><a id="index-yank_002dpop-_0028M_002dy_0029"></a><span><code class="code">yank-pop (M-y)</code><a class="copiable-link" href="#index-yank_002dpop-_0028M_002dy_0029"> ¶</a></span></dt> |
| <dd><p>Rotate the kill-ring, and yank the new top. You can only do this if |
| the prior command is <code class="code">yank</code> or <code class="code">yank-pop</code>. |
| </p></dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Numeric-Arguments"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Commands-For-Completion" accesskey="n" rel="next">Letting Readline Type For You</a>, Previous: <a href="#Commands-For-Killing" accesskey="p" rel="prev">Killing And Yanking</a>, Up: <a href="#Bindable-Readline-Commands" accesskey="u" rel="up">Bindable Readline Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Specifying-Numeric-Arguments"><span>8.4.5 Specifying Numeric Arguments<a class="copiable-link" href="#Specifying-Numeric-Arguments"> ¶</a></span></h4> |
| <dl class="ftable"> |
| <dt><a id="index-digit_002dargument-_0028M_002d0_002c-M_002d1_002c-_2026-M_002d_002d_0029"></a><span><code class="code">digit-argument (<kbd class="kbd">M-0</kbd>, <kbd class="kbd">M-1</kbd>, … <kbd class="kbd">M--</kbd>)</code><a class="copiable-link" href="#index-digit_002dargument-_0028M_002d0_002c-M_002d1_002c-_2026-M_002d_002d_0029"> ¶</a></span></dt> |
| <dd><p>Add this digit to the argument already accumulating, or start a new |
| argument. <kbd class="kbd">M--</kbd> starts a negative argument. |
| </p> |
| </dd> |
| <dt><a id="index-universal_002dargument-_0028_0029"></a><span><code class="code">universal-argument ()</code><a class="copiable-link" href="#index-universal_002dargument-_0028_0029"> ¶</a></span></dt> |
| <dd><p>This is another way to specify an argument. |
| If this command is followed by one or more digits, optionally with a |
| leading minus sign, those digits define the argument. |
| If the command is followed by digits, executing <code class="code">universal-argument</code> |
| again ends the numeric argument, but is otherwise ignored. |
| As a special case, if this command is immediately followed by a |
| character that is neither a digit nor minus sign, the argument count |
| for the next command is multiplied by four. |
| The argument count is initially one, so executing this function the |
| first time makes the argument count four, a second time makes the |
| argument count sixteen, and so on. |
| By default, this is not bound to a key. |
| </p></dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Commands-For-Completion"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Keyboard-Macros" accesskey="n" rel="next">Keyboard Macros</a>, Previous: <a href="#Numeric-Arguments" accesskey="p" rel="prev">Specifying Numeric Arguments</a>, Up: <a href="#Bindable-Readline-Commands" accesskey="u" rel="up">Bindable Readline Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Letting-Readline-Type-For-You"><span>8.4.6 Letting Readline Type For You<a class="copiable-link" href="#Letting-Readline-Type-For-You"> ¶</a></span></h4> |
| |
| <dl class="ftable"> |
| <dt><a id="index-complete-_0028TAB_0029"></a><span><code class="code">complete (<kbd class="key">TAB</kbd>)</code><a class="copiable-link" href="#index-complete-_0028TAB_0029"> ¶</a></span></dt> |
| <dd><p>Attempt to perform completion on the text before point. |
| The actual completion performed is application-specific. |
| Bash attempts completion treating the text as a variable (if the |
| text begins with ‘<samp class="samp">$</samp>’), username (if the text begins with |
| ‘<samp class="samp">~</samp>’), hostname (if the text begins with ‘<samp class="samp">@</samp>’), or |
| command (including aliases and functions) in turn. If none |
| of these produces a match, filename completion is attempted. |
| </p> |
| </dd> |
| <dt><a id="index-possible_002dcompletions-_0028M_002d_003f_0029"></a><span><code class="code">possible-completions (M-?)</code><a class="copiable-link" href="#index-possible_002dcompletions-_0028M_002d_003f_0029"> ¶</a></span></dt> |
| <dd><p>List the possible completions of the text before point. |
| When displaying completions, Readline sets the number of columns used |
| for display to the value of <code class="code">completion-display-width</code>, the value of |
| the environment variable <code class="env">COLUMNS</code>, or the screen width, in that order. |
| </p> |
| </dd> |
| <dt><a id="index-insert_002dcompletions-_0028M_002d_002a_0029"></a><span><code class="code">insert-completions (M-*)</code><a class="copiable-link" href="#index-insert_002dcompletions-_0028M_002d_002a_0029"> ¶</a></span></dt> |
| <dd><p>Insert all completions of the text before point that would have |
| been generated by <code class="code">possible-completions</code>. |
| </p> |
| </dd> |
| <dt><a id="index-menu_002dcomplete-_0028_0029"></a><span><code class="code">menu-complete ()</code><a class="copiable-link" href="#index-menu_002dcomplete-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Similar to <code class="code">complete</code>, but replaces the word to be completed |
| with a single match from the list of possible completions. |
| Repeated execution of <code class="code">menu-complete</code> steps through the list |
| of possible completions, inserting each match in turn. |
| At the end of the list of completions, the bell is rung |
| (subject to the setting of <code class="code">bell-style</code>) |
| and the original text is restored. |
| An argument of <var class="var">n</var> moves <var class="var">n</var> positions forward in the list |
| of matches; a negative argument may be used to move backward |
| through the list. |
| This command is intended to be bound to <kbd class="key">TAB</kbd>, but is unbound |
| by default. |
| </p> |
| </dd> |
| <dt><a id="index-menu_002dcomplete_002dbackward-_0028_0029"></a><span><code class="code">menu-complete-backward ()</code><a class="copiable-link" href="#index-menu_002dcomplete_002dbackward-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Identical to <code class="code">menu-complete</code>, but moves backward through the list |
| of possible completions, as if <code class="code">menu-complete</code> had been given a |
| negative argument. |
| </p> |
| </dd> |
| <dt><a id="index-delete_002dchar_002dor_002dlist-_0028_0029"></a><span><code class="code">delete-char-or-list ()</code><a class="copiable-link" href="#index-delete_002dchar_002dor_002dlist-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Deletes the character under the cursor if not at the beginning or |
| end of the line (like <code class="code">delete-char</code>). |
| If at the end of the line, behaves identically to |
| <code class="code">possible-completions</code>. |
| This command is unbound by default. |
| </p> |
| </dd> |
| <dt><a id="index-complete_002dfilename-_0028M_002d_002f_0029"></a><span><code class="code">complete-filename (M-/)</code><a class="copiable-link" href="#index-complete_002dfilename-_0028M_002d_002f_0029"> ¶</a></span></dt> |
| <dd><p>Attempt filename completion on the text before point. |
| </p> |
| </dd> |
| <dt><a id="index-possible_002dfilename_002dcompletions-_0028C_002dx-_002f_0029"></a><span><code class="code">possible-filename-completions (C-x /)</code><a class="copiable-link" href="#index-possible_002dfilename_002dcompletions-_0028C_002dx-_002f_0029"> ¶</a></span></dt> |
| <dd><p>List the possible completions of the text before point, |
| treating it as a filename. |
| </p> |
| </dd> |
| <dt><a id="index-complete_002dusername-_0028M_002d_007e_0029"></a><span><code class="code">complete-username (M-~)</code><a class="copiable-link" href="#index-complete_002dusername-_0028M_002d_007e_0029"> ¶</a></span></dt> |
| <dd><p>Attempt completion on the text before point, treating |
| it as a username. |
| </p> |
| </dd> |
| <dt><a id="index-possible_002dusername_002dcompletions-_0028C_002dx-_007e_0029"></a><span><code class="code">possible-username-completions (C-x ~)</code><a class="copiable-link" href="#index-possible_002dusername_002dcompletions-_0028C_002dx-_007e_0029"> ¶</a></span></dt> |
| <dd><p>List the possible completions of the text before point, |
| treating it as a username. |
| </p> |
| </dd> |
| <dt><a id="index-complete_002dvariable-_0028M_002d_0024_0029"></a><span><code class="code">complete-variable (M-$)</code><a class="copiable-link" href="#index-complete_002dvariable-_0028M_002d_0024_0029"> ¶</a></span></dt> |
| <dd><p>Attempt completion on the text before point, treating |
| it as a shell variable. |
| </p> |
| </dd> |
| <dt><a id="index-possible_002dvariable_002dcompletions-_0028C_002dx-_0024_0029"></a><span><code class="code">possible-variable-completions (C-x $)</code><a class="copiable-link" href="#index-possible_002dvariable_002dcompletions-_0028C_002dx-_0024_0029"> ¶</a></span></dt> |
| <dd><p>List the possible completions of the text before point, |
| treating it as a shell variable. |
| </p> |
| </dd> |
| <dt><a id="index-complete_002dhostname-_0028M_002d_0040_0029"></a><span><code class="code">complete-hostname (M-@)</code><a class="copiable-link" href="#index-complete_002dhostname-_0028M_002d_0040_0029"> ¶</a></span></dt> |
| <dd><p>Attempt completion on the text before point, treating |
| it as a hostname. |
| </p> |
| </dd> |
| <dt><a id="index-possible_002dhostname_002dcompletions-_0028C_002dx-_0040_0029"></a><span><code class="code">possible-hostname-completions (C-x @)</code><a class="copiable-link" href="#index-possible_002dhostname_002dcompletions-_0028C_002dx-_0040_0029"> ¶</a></span></dt> |
| <dd><p>List the possible completions of the text before point, |
| treating it as a hostname. |
| </p> |
| </dd> |
| <dt><a id="index-complete_002dcommand-_0028M_002d_0021_0029"></a><span><code class="code">complete-command (M-!)</code><a class="copiable-link" href="#index-complete_002dcommand-_0028M_002d_0021_0029"> ¶</a></span></dt> |
| <dd><p>Attempt completion on the text before point, treating |
| it as a command name. Command completion attempts to |
| match the text against aliases, reserved words, shell |
| functions, shell builtins, and finally executable filenames, |
| in that order. |
| </p> |
| </dd> |
| <dt><a id="index-possible_002dcommand_002dcompletions-_0028C_002dx-_0021_0029"></a><span><code class="code">possible-command-completions (C-x !)</code><a class="copiable-link" href="#index-possible_002dcommand_002dcompletions-_0028C_002dx-_0021_0029"> ¶</a></span></dt> |
| <dd><p>List the possible completions of the text before point, |
| treating it as a command name. |
| </p> |
| </dd> |
| <dt><a id="index-dynamic_002dcomplete_002dhistory-_0028M_002dTAB_0029"></a><span><code class="code">dynamic-complete-history (M-<kbd class="key">TAB</kbd>)</code><a class="copiable-link" href="#index-dynamic_002dcomplete_002dhistory-_0028M_002dTAB_0029"> ¶</a></span></dt> |
| <dd><p>Attempt completion on the text before point, comparing |
| the text against lines from the history list for possible |
| completion matches. |
| </p> |
| </dd> |
| <dt><a id="index-dabbrev_002dexpand-_0028_0029"></a><span><code class="code">dabbrev-expand ()</code><a class="copiable-link" href="#index-dabbrev_002dexpand-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Attempt menu completion on the text before point, comparing |
| the text against lines from the history list for possible |
| completion matches. |
| </p> |
| </dd> |
| <dt><a id="index-complete_002dinto_002dbraces-_0028M_002d_007b_0029"></a><span><code class="code">complete-into-braces (M-{)</code><a class="copiable-link" href="#index-complete_002dinto_002dbraces-_0028M_002d_007b_0029"> ¶</a></span></dt> |
| <dd><p>Perform filename completion and insert the list of possible completions |
| enclosed within braces so the list is available to the shell |
| (see <a class="pxref" href="#Brace-Expansion">Brace Expansion</a>). |
| </p> |
| </dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Keyboard-Macros"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Miscellaneous-Commands" accesskey="n" rel="next">Some Miscellaneous Commands</a>, Previous: <a href="#Commands-For-Completion" accesskey="p" rel="prev">Letting Readline Type For You</a>, Up: <a href="#Bindable-Readline-Commands" accesskey="u" rel="up">Bindable Readline Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Keyboard-Macros-1"><span>8.4.7 Keyboard Macros<a class="copiable-link" href="#Keyboard-Macros-1"> ¶</a></span></h4> |
| <dl class="ftable"> |
| <dt><a id="index-start_002dkbd_002dmacro-_0028C_002dx-_0028_0029"></a><span><code class="code">start-kbd-macro (C-x ()</code><a class="copiable-link" href="#index-start_002dkbd_002dmacro-_0028C_002dx-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Begin saving the characters typed into the current keyboard macro. |
| </p> |
| </dd> |
| <dt><a id="index-end_002dkbd_002dmacro-_0028C_002dx-_0029_0029"></a><span><code class="code">end-kbd-macro (C-x ))</code><a class="copiable-link" href="#index-end_002dkbd_002dmacro-_0028C_002dx-_0029_0029"> ¶</a></span></dt> |
| <dd><p>Stop saving the characters typed into the current keyboard macro |
| and save the definition. |
| </p> |
| </dd> |
| <dt><a id="index-call_002dlast_002dkbd_002dmacro-_0028C_002dx-e_0029"></a><span><code class="code">call-last-kbd-macro (C-x e)</code><a class="copiable-link" href="#index-call_002dlast_002dkbd_002dmacro-_0028C_002dx-e_0029"> ¶</a></span></dt> |
| <dd><p>Re-execute the last keyboard macro defined, by making the characters |
| in the macro appear as if typed at the keyboard. |
| </p> |
| </dd> |
| <dt><a id="index-print_002dlast_002dkbd_002dmacro-_0028_0029"></a><span><code class="code">print-last-kbd-macro ()</code><a class="copiable-link" href="#index-print_002dlast_002dkbd_002dmacro-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Print the last keyboard macro defined in a format suitable for the |
| <var class="var">inputrc</var> file. |
| </p> |
| </dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Miscellaneous-Commands"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Keyboard-Macros" accesskey="p" rel="prev">Keyboard Macros</a>, Up: <a href="#Bindable-Readline-Commands" accesskey="u" rel="up">Bindable Readline Commands</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Some-Miscellaneous-Commands"><span>8.4.8 Some Miscellaneous Commands<a class="copiable-link" href="#Some-Miscellaneous-Commands"> ¶</a></span></h4> |
| <dl class="ftable"> |
| <dt><a id="index-re_002dread_002dinit_002dfile-_0028C_002dx-C_002dr_0029"></a><span><code class="code">re-read-init-file (C-x C-r)</code><a class="copiable-link" href="#index-re_002dread_002dinit_002dfile-_0028C_002dx-C_002dr_0029"> ¶</a></span></dt> |
| <dd><p>Read in the contents of the <var class="var">inputrc</var> file, and incorporate |
| any bindings or variable assignments found there. |
| </p> |
| </dd> |
| <dt><a id="index-abort-_0028C_002dg_0029"></a><span><code class="code">abort (C-g)</code><a class="copiable-link" href="#index-abort-_0028C_002dg_0029"> ¶</a></span></dt> |
| <dd><p>Abort the current editing command and |
| ring the terminal’s bell (subject to the setting of |
| <code class="code">bell-style</code>). |
| </p> |
| </dd> |
| <dt><a id="index-do_002dlowercase_002dversion-_0028M_002dA_002c-M_002dB_002c-M_002dx_002c-_2026_0029"></a><span><code class="code">do-lowercase-version (M-A, M-B, M-<var class="var">x</var>, …)</code><a class="copiable-link" href="#index-do_002dlowercase_002dversion-_0028M_002dA_002c-M_002dB_002c-M_002dx_002c-_2026_0029"> ¶</a></span></dt> |
| <dd><p>If the metafied character <var class="var">x</var> is upper case, run the command |
| that is bound to the corresponding metafied lower case character. |
| The behavior is undefined if <var class="var">x</var> is already lower case. |
| </p> |
| </dd> |
| <dt><a id="index-prefix_002dmeta-_0028ESC_0029"></a><span><code class="code">prefix-meta (<kbd class="key">ESC</kbd>)</code><a class="copiable-link" href="#index-prefix_002dmeta-_0028ESC_0029"> ¶</a></span></dt> |
| <dd><p>Metafy the next character typed. This is for keyboards |
| without a meta key. Typing ‘<samp class="samp"><kbd class="key">ESC</kbd> f</samp>’ is equivalent to typing |
| <kbd class="kbd">M-f</kbd>. |
| </p> |
| </dd> |
| <dt><a id="index-undo-_0028C_002d_005f-or-C_002dx-C_002du_0029"></a><span><code class="code">undo (C-_ or C-x C-u)</code><a class="copiable-link" href="#index-undo-_0028C_002d_005f-or-C_002dx-C_002du_0029"> ¶</a></span></dt> |
| <dd><p>Incremental undo, separately remembered for each line. |
| </p> |
| </dd> |
| <dt><a id="index-revert_002dline-_0028M_002dr_0029"></a><span><code class="code">revert-line (M-r)</code><a class="copiable-link" href="#index-revert_002dline-_0028M_002dr_0029"> ¶</a></span></dt> |
| <dd><p>Undo all changes made to this line. This is like executing the <code class="code">undo</code> |
| command enough times to get back to the beginning. |
| </p> |
| </dd> |
| <dt><a id="index-tilde_002dexpand-_0028M_002d_0026_0029"></a><span><code class="code">tilde-expand (M-&)</code><a class="copiable-link" href="#index-tilde_002dexpand-_0028M_002d_0026_0029"> ¶</a></span></dt> |
| <dd><p>Perform tilde expansion on the current word. |
| </p> |
| </dd> |
| <dt><a id="index-set_002dmark-_0028C_002d_0040_0029"></a><span><code class="code">set-mark (C-@)</code><a class="copiable-link" href="#index-set_002dmark-_0028C_002d_0040_0029"> ¶</a></span></dt> |
| <dd><p>Set the mark to the point. If a |
| numeric argument is supplied, the mark is set to that position. |
| </p> |
| </dd> |
| <dt><a id="index-exchange_002dpoint_002dand_002dmark-_0028C_002dx-C_002dx_0029"></a><span><code class="code">exchange-point-and-mark (C-x C-x)</code><a class="copiable-link" href="#index-exchange_002dpoint_002dand_002dmark-_0028C_002dx-C_002dx_0029"> ¶</a></span></dt> |
| <dd><p>Swap the point with the mark. The current cursor position is set to |
| the saved position, and the old cursor position is saved as the mark. |
| </p> |
| </dd> |
| <dt><a id="index-character_002dsearch-_0028C_002d_005d_0029"></a><span><code class="code">character-search (C-])</code><a class="copiable-link" href="#index-character_002dsearch-_0028C_002d_005d_0029"> ¶</a></span></dt> |
| <dd><p>A character is read and point is moved to the next occurrence of that |
| character. A negative argument searches for previous occurrences. |
| </p> |
| </dd> |
| <dt><a id="index-character_002dsearch_002dbackward-_0028M_002dC_002d_005d_0029"></a><span><code class="code">character-search-backward (M-C-])</code><a class="copiable-link" href="#index-character_002dsearch_002dbackward-_0028M_002dC_002d_005d_0029"> ¶</a></span></dt> |
| <dd><p>A character is read and point is moved to the previous occurrence |
| of that character. A negative argument searches for subsequent |
| occurrences. |
| </p> |
| </dd> |
| <dt><a id="index-skip_002dcsi_002dsequence-_0028_0029"></a><span><code class="code">skip-csi-sequence ()</code><a class="copiable-link" href="#index-skip_002dcsi_002dsequence-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Read enough characters to consume a multi-key sequence such as those |
| defined for keys like Home and End. Such sequences begin with a |
| Control Sequence Indicator (CSI), usually ESC-[. If this sequence is |
| bound to "\e[", keys producing such sequences will have no effect |
| unless explicitly bound to a Readline command, instead of inserting |
| stray characters into the editing buffer. This is unbound by default, |
| but usually bound to ESC-[. |
| </p> |
| </dd> |
| <dt><a id="index-insert_002dcomment-_0028M_002d_0023_0029"></a><span><code class="code">insert-comment (M-#)</code><a class="copiable-link" href="#index-insert_002dcomment-_0028M_002d_0023_0029"> ¶</a></span></dt> |
| <dd><p>Without a numeric argument, the value of the <code class="code">comment-begin</code> |
| variable is inserted at the beginning of the current line. |
| If a numeric argument is supplied, this command acts as a toggle: if |
| the characters at the beginning of the line do not match the value |
| of <code class="code">comment-begin</code>, the value is inserted, otherwise |
| the characters in <code class="code">comment-begin</code> are deleted from the beginning of |
| the line. |
| In either case, the line is accepted as if a newline had been typed. |
| The default value of <code class="code">comment-begin</code> causes this command |
| to make the current line a shell comment. |
| If a numeric argument causes the comment character to be removed, the line |
| will be executed by the shell. |
| </p> |
| </dd> |
| <dt><a id="index-dump_002dfunctions-_0028_0029"></a><span><code class="code">dump-functions ()</code><a class="copiable-link" href="#index-dump_002dfunctions-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Print all of the functions and their key bindings to the |
| Readline output stream. If a numeric argument is supplied, |
| the output is formatted in such a way that it can be made part |
| of an <var class="var">inputrc</var> file. This command is unbound by default. |
| </p> |
| </dd> |
| <dt><a id="index-dump_002dvariables-_0028_0029"></a><span><code class="code">dump-variables ()</code><a class="copiable-link" href="#index-dump_002dvariables-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Print all of the settable variables and their values to the |
| Readline output stream. If a numeric argument is supplied, |
| the output is formatted in such a way that it can be made part |
| of an <var class="var">inputrc</var> file. This command is unbound by default. |
| </p> |
| </dd> |
| <dt><a id="index-dump_002dmacros-_0028_0029"></a><span><code class="code">dump-macros ()</code><a class="copiable-link" href="#index-dump_002dmacros-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Print all of the Readline key sequences bound to macros and the |
| strings they output. If a numeric argument is supplied, |
| the output is formatted in such a way that it can be made part |
| of an <var class="var">inputrc</var> file. This command is unbound by default. |
| </p> |
| </dd> |
| <dt><a id="index-spell_002dcorrect_002dword-_0028C_002dx-s_0029"></a><span><code class="code">spell-correct-word (C-x s)</code><a class="copiable-link" href="#index-spell_002dcorrect_002dword-_0028C_002dx-s_0029"> ¶</a></span></dt> |
| <dd><p>Perform spelling correction on the current word, treating it as a directory |
| or filename, in the same way as the <code class="code">cdspell</code> shell option. |
| Word boundaries are the same as those used by <code class="code">shell-forward-word</code>. |
| </p> |
| </dd> |
| <dt><a id="index-glob_002dcomplete_002dword-_0028M_002dg_0029"></a><span><code class="code">glob-complete-word (M-g)</code><a class="copiable-link" href="#index-glob_002dcomplete_002dword-_0028M_002dg_0029"> ¶</a></span></dt> |
| <dd><p>The word before point is treated as a pattern for pathname expansion, |
| with an asterisk implicitly appended. This pattern is used to |
| generate a list of matching file names for possible completions. |
| </p> |
| </dd> |
| <dt><a id="index-glob_002dexpand_002dword-_0028C_002dx-_002a_0029"></a><span><code class="code">glob-expand-word (C-x *)</code><a class="copiable-link" href="#index-glob_002dexpand_002dword-_0028C_002dx-_002a_0029"> ¶</a></span></dt> |
| <dd><p>The word before point is treated as a pattern for pathname expansion, |
| and the list of matching file names is inserted, replacing the word. |
| If a numeric argument is supplied, a ‘<samp class="samp">*</samp>’ is appended before |
| pathname expansion. |
| </p> |
| </dd> |
| <dt><a id="index-glob_002dlist_002dexpansions-_0028C_002dx-g_0029"></a><span><code class="code">glob-list-expansions (C-x g)</code><a class="copiable-link" href="#index-glob_002dlist_002dexpansions-_0028C_002dx-g_0029"> ¶</a></span></dt> |
| <dd><p>The list of expansions that would have been generated by |
| <code class="code">glob-expand-word</code> is displayed, and the line is redrawn. |
| If a numeric argument is supplied, a ‘<samp class="samp">*</samp>’ is appended before |
| pathname expansion. |
| </p> |
| </dd> |
| <dt><a id="index-display_002dshell_002dversion-_0028C_002dx-C_002dv_0029"></a><span><code class="code">display-shell-version (C-x C-v)</code><a class="copiable-link" href="#index-display_002dshell_002dversion-_0028C_002dx-C_002dv_0029"> ¶</a></span></dt> |
| <dd><p>Display version information about the current instance of Bash. |
| </p> |
| </dd> |
| <dt><a id="index-shell_002dexpand_002dline-_0028M_002dC_002de_0029"></a><span><code class="code">shell-expand-line (M-C-e)</code><a class="copiable-link" href="#index-shell_002dexpand_002dline-_0028M_002dC_002de_0029"> ¶</a></span></dt> |
| <dd><p>Expand the line as the shell does. |
| This performs alias and history expansion as well as all of the shell |
| word expansions (see <a class="pxref" href="#Shell-Expansions">Shell Expansions</a>). |
| </p> |
| </dd> |
| <dt><a id="index-history_002dexpand_002dline-_0028M_002d_005e_0029"></a><span><code class="code">history-expand-line (M-^)</code><a class="copiable-link" href="#index-history_002dexpand_002dline-_0028M_002d_005e_0029"> ¶</a></span></dt> |
| <dd><p>Perform history expansion on the current line. |
| </p> |
| </dd> |
| <dt><a id="index-magic_002dspace-_0028_0029"></a><span><code class="code">magic-space ()</code><a class="copiable-link" href="#index-magic_002dspace-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Perform history expansion on the current line and insert a space |
| (see <a class="pxref" href="#History-Interaction">History Expansion</a>). |
| </p> |
| </dd> |
| <dt><a id="index-alias_002dexpand_002dline-_0028_0029"></a><span><code class="code">alias-expand-line ()</code><a class="copiable-link" href="#index-alias_002dexpand_002dline-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Perform alias expansion on the current line (see <a class="pxref" href="#Aliases">Aliases</a>). |
| </p> |
| </dd> |
| <dt><a id="index-history_002dand_002dalias_002dexpand_002dline-_0028_0029"></a><span><code class="code">history-and-alias-expand-line ()</code><a class="copiable-link" href="#index-history_002dand_002dalias_002dexpand_002dline-_0028_0029"> ¶</a></span></dt> |
| <dd><p>Perform history and alias expansion on the current line. |
| </p> |
| </dd> |
| <dt><a id="index-insert_002dlast_002dargument-_0028M_002d_002e-or-M_002d_005f_0029"></a><span><code class="code">insert-last-argument (M-. or M-_)</code><a class="copiable-link" href="#index-insert_002dlast_002dargument-_0028M_002d_002e-or-M_002d_005f_0029"> ¶</a></span></dt> |
| <dd><p>A synonym for <code class="code">yank-last-arg</code>. |
| </p> |
| </dd> |
| <dt><a id="index-edit_002dand_002dexecute_002dcommand-_0028C_002dx-C_002de_0029"></a><span><code class="code">edit-and-execute-command (C-x C-e)</code><a class="copiable-link" href="#index-edit_002dand_002dexecute_002dcommand-_0028C_002dx-C_002de_0029"> ¶</a></span></dt> |
| <dd><p>Invoke an editor on the current command line, and execute the result as shell |
| commands. |
| Bash attempts to invoke |
| <code class="code">$VISUAL</code>, <code class="code">$EDITOR</code>, and <code class="code">emacs</code> |
| as the editor, in that order. |
| </p> |
| |
| |
| </dd> |
| </dl> |
| |
| <hr> |
| </div> |
| </div> |
| <div class="section-level-extent" id="Readline-vi-Mode"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Programmable-Completion" accesskey="n" rel="next">Programmable Completion</a>, Previous: <a href="#Bindable-Readline-Commands" accesskey="p" rel="prev">Bindable Readline Commands</a>, Up: <a href="#Command-Line-Editing" accesskey="u" rel="up">Command Line Editing</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Readline-vi-Mode-1"><span>8.5 Readline vi Mode<a class="copiable-link" href="#Readline-vi-Mode-1"> ¶</a></span></h3> |
| |
| <p>While the Readline library does not have a full set of <code class="code">vi</code> |
| editing functions, it does contain enough to allow simple editing |
| of the line. The Readline <code class="code">vi</code> mode behaves as specified in |
| the <small class="sc">POSIX</small> standard. |
| </p> |
| <p>In order to switch interactively between <code class="code">emacs</code> and <code class="code">vi</code> |
| editing modes, use the ‘<samp class="samp">set -o emacs</samp>’ and ‘<samp class="samp">set -o vi</samp>’ |
| commands (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>). |
| The Readline default is <code class="code">emacs</code> mode. |
| </p> |
| <p>When you enter a line in <code class="code">vi</code> mode, you are already placed in |
| ‘insertion’ mode, as if you had typed an ‘<samp class="samp">i</samp>’. Pressing <kbd class="key">ESC</kbd> |
| switches you into ‘command’ mode, where you can edit the text of the |
| line with the standard <code class="code">vi</code> movement keys, move to previous |
| history lines with ‘<samp class="samp">k</samp>’ and subsequent lines with ‘<samp class="samp">j</samp>’, and |
| so forth. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Programmable-Completion"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Programmable-Completion-Builtins" accesskey="n" rel="next">Programmable Completion Builtins</a>, Previous: <a href="#Readline-vi-Mode" accesskey="p" rel="prev">Readline vi Mode</a>, Up: <a href="#Command-Line-Editing" accesskey="u" rel="up">Command Line Editing</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Programmable-Completion-1"><span>8.6 Programmable Completion<a class="copiable-link" href="#Programmable-Completion-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-programmable-completion"></a> |
| |
| <p>When word completion is attempted for an argument to a command for |
| which a completion specification (a <var class="var">compspec</var>) has been defined |
| using the <code class="code">complete</code> builtin (see <a class="pxref" href="#Programmable-Completion-Builtins">Programmable Completion Builtins</a>), |
| the programmable completion facilities are invoked. |
| </p> |
| <p>First, the command name is identified. |
| If a compspec has been defined for that command, the |
| compspec is used to generate the list of possible completions for the word. |
| If the command word is the empty string (completion attempted at the |
| beginning of an empty line), any compspec defined with |
| the <samp class="option">-E</samp> option to <code class="code">complete</code> is used. |
| If the command word is a full pathname, a compspec for the full |
| pathname is searched for first. |
| If no compspec is found for the full pathname, an attempt is made to |
| find a compspec for the portion following the final slash. |
| If those searches do not result in a compspec, any compspec defined with |
| the <samp class="option">-D</samp> option to <code class="code">complete</code> is used as the default. |
| If there is no default compspec, Bash attempts alias expansion |
| on the command word as a final resort, and attempts to find a compspec |
| for the command word from any successful expansion |
| </p> |
| <p>Once a compspec has been found, it is used to generate the list of |
| matching words. |
| If a compspec is not found, the default Bash completion |
| described above (see <a class="pxref" href="#Commands-For-Completion">Letting Readline Type For You</a>) is performed. |
| </p> |
| <p>First, the actions specified by the compspec are used. |
| Only matches which are prefixed by the word being completed are |
| returned. |
| When the <samp class="option">-f</samp> or <samp class="option">-d</samp> option is used for filename or |
| directory name completion, the shell variable <code class="env">FIGNORE</code> is |
| used to filter the matches. |
| See <a class="xref" href="#Bash-Variables">Bash Variables</a>, for a description of <code class="env">FIGNORE</code>. |
| </p> |
| <p>Any completions specified by a filename expansion pattern to the |
| <samp class="option">-G</samp> option are generated next. |
| The words generated by the pattern need not match the word being completed. |
| The <code class="env">GLOBIGNORE</code> shell variable is not used to filter the matches, |
| but the <code class="env">FIGNORE</code> shell variable is used. |
| </p> |
| <p>Next, the string specified as the argument to the <samp class="option">-W</samp> option |
| is considered. |
| The string is first split using the characters in the <code class="env">IFS</code> |
| special variable as delimiters. |
| Shell quoting is honored within the string, in order to provide a |
| mechanism for the words to contain shell metacharacters or characters |
| in the value of <code class="env">IFS</code>. |
| Each word is then expanded using |
| brace expansion, tilde expansion, parameter and variable expansion, |
| command substitution, and arithmetic expansion, |
| as described above (see <a class="pxref" href="#Shell-Expansions">Shell Expansions</a>). |
| The results are split using the rules described above |
| (see <a class="pxref" href="#Word-Splitting">Word Splitting</a>). |
| The results of the expansion are prefix-matched against the word being |
| completed, and the matching words become the possible completions. |
| </p> |
| <p>After these matches have been generated, any shell function or command |
| specified with the <samp class="option">-F</samp> and <samp class="option">-C</samp> options is invoked. |
| When the command or function is invoked, the <code class="env">COMP_LINE</code>, |
| <code class="env">COMP_POINT</code>, <code class="env">COMP_KEY</code>, and <code class="env">COMP_TYPE</code> variables are |
| assigned values as described above (see <a class="pxref" href="#Bash-Variables">Bash Variables</a>). |
| If a shell function is being invoked, the <code class="env">COMP_WORDS</code> and |
| <code class="env">COMP_CWORD</code> variables are also set. |
| When the function or command is invoked, the first argument ($1) is the |
| name of the command whose arguments are being completed, the |
| second argument ($2) is the word being completed, and the third argument |
| ($3) is the word preceding the word being completed on the current command |
| line. |
| No filtering of the generated completions against the word being completed |
| is performed; the function or command has complete freedom in generating |
| the matches. |
| </p> |
| <p>Any function specified with <samp class="option">-F</samp> is invoked first. |
| The function may use any of the shell facilities, including the |
| <code class="code">compgen</code> and <code class="code">compopt</code> builtins described below |
| (see <a class="pxref" href="#Programmable-Completion-Builtins">Programmable Completion Builtins</a>), to generate the matches. |
| It must put the possible completions in the <code class="env">COMPREPLY</code> array |
| variable, one per array element. |
| </p> |
| <p>Next, any command specified with the <samp class="option">-C</samp> option is invoked |
| in an environment equivalent to command substitution. |
| It should print a list of completions, one per line, to |
| the standard output. |
| Backslash may be used to escape a newline, if necessary. |
| </p> |
| <p>After all of the possible completions are generated, any filter |
| specified with the <samp class="option">-X</samp> option is applied to the list. |
| The filter is a pattern as used for pathname expansion; a ‘<samp class="samp">&</samp>’ |
| in the pattern is replaced with the text of the word being completed. |
| A literal ‘<samp class="samp">&</samp>’ may be escaped with a backslash; the backslash |
| is removed before attempting a match. |
| Any completion that matches the pattern will be removed from the list. |
| A leading ‘<samp class="samp">!</samp>’ negates the pattern; in this case any completion |
| not matching the pattern will be removed. |
| If the <code class="code">nocasematch</code> shell option |
| (see the description of <code class="code">shopt</code> in <a class="ref" href="#The-Shopt-Builtin">The Shopt Builtin</a>) |
| is enabled, the match is performed without regard to the case |
| of alphabetic characters. |
| </p> |
| <p>Finally, any prefix and suffix specified with the <samp class="option">-P</samp> and <samp class="option">-S</samp> |
| options are added to each member of the completion list, and the result is |
| returned to the Readline completion code as the list of possible |
| completions. |
| </p> |
| <p>If the previously-applied actions do not generate any matches, and the |
| <samp class="option">-o dirnames</samp> option was supplied to <code class="code">complete</code> when the |
| compspec was defined, directory name completion is attempted. |
| </p> |
| <p>If the <samp class="option">-o plusdirs</samp> option was supplied to <code class="code">complete</code> when |
| the compspec was defined, directory name completion is attempted and any |
| matches are added to the results of the other actions. |
| </p> |
| <p>By default, if a compspec is found, whatever it generates is returned to |
| the completion code as the full set of possible completions. |
| The default Bash completions are not attempted, and the Readline default |
| of filename completion is disabled. |
| If the <samp class="option">-o bashdefault</samp> option was supplied to <code class="code">complete</code> when |
| the compspec was defined, the default Bash completions are attempted |
| if the compspec generates no matches. |
| If the <samp class="option">-o default</samp> option was supplied to <code class="code">complete</code> when the |
| compspec was defined, Readline’s default completion will be performed |
| if the compspec (and, if attempted, the default Bash completions) |
| generate no matches. |
| </p> |
| <p>When a compspec indicates that directory name completion is desired, |
| the programmable completion functions force Readline to append a slash |
| to completed names which are symbolic links to directories, subject to |
| the value of the <var class="var">mark-directories</var> Readline variable, regardless |
| of the setting of the <var class="var">mark-symlinked-directories</var> Readline variable. |
| </p> |
| <p>There is some support for dynamically modifying completions. This is |
| most useful when used in combination with a default completion specified |
| with <samp class="option">-D</samp>. It’s possible for shell functions executed as completion |
| handlers to indicate that completion should be retried by returning an |
| exit status of 124. If a shell function returns 124, and changes |
| the compspec associated with the command on which completion is being |
| attempted (supplied as the first argument when the function is executed), |
| programmable completion restarts from the beginning, with an |
| attempt to find a new compspec for that command. This allows a set of |
| completions to be built dynamically as completion is attempted, rather than |
| being loaded all at once. |
| </p> |
| <p>For instance, assuming that there is a library of compspecs, each kept in a |
| file corresponding to the name of the command, the following default |
| completion function would load completions dynamically: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">_completion_loader() |
| { |
| . "/etc/bash_completion.d/$1.sh" >/dev/null 2>&1 && return 124 |
| } |
| complete -D -F _completion_loader -o bashdefault -o default |
| </pre></div> |
| |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Programmable-Completion-Builtins"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#A-Programmable-Completion-Example" accesskey="n" rel="next">A Programmable Completion Example</a>, Previous: <a href="#Programmable-Completion" accesskey="p" rel="prev">Programmable Completion</a>, Up: <a href="#Command-Line-Editing" accesskey="u" rel="up">Command Line Editing</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Programmable-Completion-Builtins-1"><span>8.7 Programmable Completion Builtins<a class="copiable-link" href="#Programmable-Completion-Builtins-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-completion-builtins"></a> |
| |
| <p>Three builtin commands are available to manipulate the programmable completion |
| facilities: one to specify how the arguments to a particular command are to |
| be completed, and two to modify the completion as it is happening. |
| </p> |
| <dl class="table"> |
| <dt><a id="index-compgen"></a><span><code class="code">compgen</code><a class="copiable-link" href="#index-compgen"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted"><code class="code">compgen [<var class="var">option</var>] [<var class="var">word</var>]</code> |
| </pre></div> |
| |
| <p>Generate possible completion matches for <var class="var">word</var> according to |
| the <var class="var">option</var>s, which may be any option accepted by the |
| <code class="code">complete</code> |
| builtin with the exception of <samp class="option">-p</samp> and <samp class="option">-r</samp>, and write |
| the matches to the standard output. |
| When using the <samp class="option">-F</samp> or <samp class="option">-C</samp> options, the various shell variables |
| set by the programmable completion facilities, while available, will not |
| have useful values. |
| </p> |
| <p>The matches will be generated in the same way as if the programmable |
| completion code had generated them directly from a completion specification |
| with the same flags. |
| If <var class="var">word</var> is specified, only those completions matching <var class="var">word</var> |
| will be displayed. |
| </p> |
| <p>The return value is true unless an invalid option is supplied, or no |
| matches were generated. |
| </p> |
| </dd> |
| <dt><a id="index-complete"></a><span><code class="code">complete</code><a class="copiable-link" href="#index-complete"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted"><code class="code">complete [-abcdefgjksuv] [-o <var class="var">comp-option</var>] [-DEI] [-A <var class="var">action</var>] [-G <var class="var">globpat</var>] |
| [-W <var class="var">wordlist</var>] [-F <var class="var">function</var>] [-C <var class="var">command</var>] [-X <var class="var">filterpat</var>] |
| [-P <var class="var">prefix</var>] [-S <var class="var">suffix</var>] <var class="var">name</var> [<var class="var">name</var> ...]</code> |
| <code class="code">complete -pr [-DEI] [<var class="var">name</var> ...]</code> |
| </pre></div> |
| |
| <p>Specify how arguments to each <var class="var">name</var> should be completed. |
| If the <samp class="option">-p</samp> option is supplied, or if no options are supplied, existing |
| completion specifications are printed in a way that allows them to be |
| reused as input. |
| The <samp class="option">-r</samp> option removes a completion specification for |
| each <var class="var">name</var>, or, if no <var class="var">name</var>s are supplied, all |
| completion specifications. |
| The <samp class="option">-D</samp> option indicates that other supplied options and actions should |
| apply to the “default” command completion; that is, completion attempted |
| on a command for which no completion has previously been defined. |
| The <samp class="option">-E</samp> option indicates that other supplied options and actions should |
| apply to “empty” command completion; that is, completion attempted on a |
| blank line. |
| The <samp class="option">-I</samp> option indicates that other supplied options and actions should |
| apply to completion on the initial non-assignment word on the line, or after a |
| command delimiter such as ‘<samp class="samp">;</samp>’ or ‘<samp class="samp">|</samp>’, which is usually command |
| name completion. |
| If multiple options are supplied, the <samp class="option">-D</samp> option takes precedence |
| over <samp class="option">-E</samp>, and both take precedence over <samp class="option">-I</samp>. |
| If any of <samp class="option">-D</samp>, <samp class="option">-E</samp>, or <samp class="option">-I</samp> are supplied, any other |
| <var class="var">name</var> arguments are ignored; these completions only apply to the case |
| specified by the option. |
| </p> |
| <p>The process of applying these completion specifications when word completion |
| is attempted is described above (see <a class="pxref" href="#Programmable-Completion">Programmable Completion</a>). |
| </p> |
| <p>Other options, if specified, have the following meanings. |
| The arguments to the <samp class="option">-G</samp>, <samp class="option">-W</samp>, and <samp class="option">-X</samp> options |
| (and, if necessary, the <samp class="option">-P</samp> and <samp class="option">-S</samp> options) |
| should be quoted to protect them from expansion before the |
| <code class="code">complete</code> builtin is invoked. |
| </p> |
| |
| <dl class="table"> |
| <dt><code class="code">-o <var class="var">comp-option</var></code></dt> |
| <dd><p>The <var class="var">comp-option</var> controls several aspects of the compspec’s behavior |
| beyond the simple generation of completions. |
| <var class="var">comp-option</var> may be one of: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">bashdefault</code></dt> |
| <dd><p>Perform the rest of the default Bash completions if the compspec |
| generates no matches. |
| </p> |
| </dd> |
| <dt><code class="code">default</code></dt> |
| <dd><p>Use Readline’s default filename completion if the compspec generates |
| no matches. |
| </p> |
| </dd> |
| <dt><code class="code">dirnames</code></dt> |
| <dd><p>Perform directory name completion if the compspec generates no matches. |
| </p> |
| </dd> |
| <dt><code class="code">filenames</code></dt> |
| <dd><p>Tell Readline that the compspec generates filenames, so it can perform any |
| filename-specific processing (like adding a slash to directory names, |
| quoting special characters, or suppressing trailing spaces). |
| This option is intended to be used with shell functions specified |
| with <samp class="option">-F</samp>. |
| </p> |
| </dd> |
| <dt><code class="code">noquote</code></dt> |
| <dd><p>Tell Readline not to quote the completed words if they are filenames |
| (quoting filenames is the default). |
| </p> |
| </dd> |
| <dt><code class="code">nosort</code></dt> |
| <dd><p>Tell Readline not to sort the list of possible completions alphabetically. |
| </p> |
| </dd> |
| <dt><code class="code">nospace</code></dt> |
| <dd><p>Tell Readline not to append a space (the default) to words completed at |
| the end of the line. |
| </p> |
| </dd> |
| <dt><code class="code">plusdirs</code></dt> |
| <dd><p>After any matches defined by the compspec are generated, |
| directory name completion is attempted and any |
| matches are added to the results of the other actions. |
| </p> |
| </dd> |
| </dl> |
| |
| </dd> |
| <dt><code class="code">-A <var class="var">action</var></code></dt> |
| <dd><p>The <var class="var">action</var> may be one of the following to generate a list of possible |
| completions: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">alias</code></dt> |
| <dd><p>Alias names. May also be specified as <samp class="option">-a</samp>. |
| </p> |
| </dd> |
| <dt><code class="code">arrayvar</code></dt> |
| <dd><p>Array variable names. |
| </p> |
| </dd> |
| <dt><code class="code">binding</code></dt> |
| <dd><p>Readline key binding names (see <a class="pxref" href="#Bindable-Readline-Commands">Bindable Readline Commands</a>). |
| </p> |
| </dd> |
| <dt><code class="code">builtin</code></dt> |
| <dd><p>Names of shell builtin commands. May also be specified as <samp class="option">-b</samp>. |
| </p> |
| </dd> |
| <dt><code class="code">command</code></dt> |
| <dd><p>Command names. May also be specified as <samp class="option">-c</samp>. |
| </p> |
| </dd> |
| <dt><code class="code">directory</code></dt> |
| <dd><p>Directory names. May also be specified as <samp class="option">-d</samp>. |
| </p> |
| </dd> |
| <dt><code class="code">disabled</code></dt> |
| <dd><p>Names of disabled shell builtins. |
| </p> |
| </dd> |
| <dt><code class="code">enabled</code></dt> |
| <dd><p>Names of enabled shell builtins. |
| </p> |
| </dd> |
| <dt><code class="code">export</code></dt> |
| <dd><p>Names of exported shell variables. May also be specified as <samp class="option">-e</samp>. |
| </p> |
| </dd> |
| <dt><code class="code">file</code></dt> |
| <dd><p>File names. May also be specified as <samp class="option">-f</samp>. |
| </p> |
| </dd> |
| <dt><code class="code">function</code></dt> |
| <dd><p>Names of shell functions. |
| </p> |
| </dd> |
| <dt><code class="code">group</code></dt> |
| <dd><p>Group names. May also be specified as <samp class="option">-g</samp>. |
| </p> |
| </dd> |
| <dt><code class="code">helptopic</code></dt> |
| <dd><p>Help topics as accepted by the <code class="code">help</code> builtin (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>). |
| </p> |
| </dd> |
| <dt><code class="code">hostname</code></dt> |
| <dd><p>Hostnames, as taken from the file specified by the |
| <code class="env">HOSTFILE</code> shell variable (see <a class="pxref" href="#Bash-Variables">Bash Variables</a>). |
| </p> |
| </dd> |
| <dt><code class="code">job</code></dt> |
| <dd><p>Job names, if job control is active. May also be specified as <samp class="option">-j</samp>. |
| </p> |
| </dd> |
| <dt><code class="code">keyword</code></dt> |
| <dd><p>Shell reserved words. May also be specified as <samp class="option">-k</samp>. |
| </p> |
| </dd> |
| <dt><code class="code">running</code></dt> |
| <dd><p>Names of running jobs, if job control is active. |
| </p> |
| </dd> |
| <dt><code class="code">service</code></dt> |
| <dd><p>Service names. May also be specified as <samp class="option">-s</samp>. |
| </p> |
| </dd> |
| <dt><code class="code">setopt</code></dt> |
| <dd><p>Valid arguments for the <samp class="option">-o</samp> option to the <code class="code">set</code> builtin |
| (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>). |
| </p> |
| </dd> |
| <dt><code class="code">shopt</code></dt> |
| <dd><p>Shell option names as accepted by the <code class="code">shopt</code> builtin |
| (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>). |
| </p> |
| </dd> |
| <dt><code class="code">signal</code></dt> |
| <dd><p>Signal names. |
| </p> |
| </dd> |
| <dt><code class="code">stopped</code></dt> |
| <dd><p>Names of stopped jobs, if job control is active. |
| </p> |
| </dd> |
| <dt><code class="code">user</code></dt> |
| <dd><p>User names. May also be specified as <samp class="option">-u</samp>. |
| </p> |
| </dd> |
| <dt><code class="code">variable</code></dt> |
| <dd><p>Names of all shell variables. May also be specified as <samp class="option">-v</samp>. |
| </p></dd> |
| </dl> |
| |
| </dd> |
| <dt><code class="code">-C <var class="var">command</var></code></dt> |
| <dd><p><var class="var">command</var> is executed in a subshell environment, and its output is |
| used as the possible completions. |
| Arguments are passed as with the <samp class="option">-F</samp> option. |
| </p> |
| </dd> |
| <dt><code class="code">-F <var class="var">function</var></code></dt> |
| <dd><p>The shell function <var class="var">function</var> is executed in the current shell |
| environment. |
| When it is executed, $1 is the name of the command whose arguments are |
| being completed, $2 is the word being completed, and $3 is the word |
| preceding the word being completed, as described above |
| (see <a class="pxref" href="#Programmable-Completion">Programmable Completion</a>). |
| When it finishes, the possible completions are retrieved from the value |
| of the <code class="env">COMPREPLY</code> array variable. |
| </p> |
| </dd> |
| <dt><code class="code">-G <var class="var">globpat</var></code></dt> |
| <dd><p>The filename expansion pattern <var class="var">globpat</var> is expanded to generate |
| the possible completions. |
| </p> |
| </dd> |
| <dt><code class="code">-P <var class="var">prefix</var></code></dt> |
| <dd><p><var class="var">prefix</var> is added at the beginning of each possible completion |
| after all other options have been applied. |
| </p> |
| </dd> |
| <dt><code class="code">-S <var class="var">suffix</var></code></dt> |
| <dd><p><var class="var">suffix</var> is appended to each possible completion |
| after all other options have been applied. |
| </p> |
| </dd> |
| <dt><code class="code">-W <var class="var">wordlist</var></code></dt> |
| <dd><p>The <var class="var">wordlist</var> is split using the characters in the |
| <code class="env">IFS</code> special variable as delimiters, and each resultant word |
| is expanded. |
| The possible completions are the members of the resultant list which |
| match the word being completed. |
| </p> |
| </dd> |
| <dt><code class="code">-X <var class="var">filterpat</var></code></dt> |
| <dd><p><var class="var">filterpat</var> is a pattern as used for filename expansion. |
| It is applied to the list of possible completions generated by the |
| preceding options and arguments, and each completion matching |
| <var class="var">filterpat</var> is removed from the list. |
| A leading ‘<samp class="samp">!</samp>’ in <var class="var">filterpat</var> negates the pattern; in this |
| case, any completion not matching <var class="var">filterpat</var> is removed. |
| </p></dd> |
| </dl> |
| |
| <p>The return value is true unless an invalid option is supplied, an option |
| other than <samp class="option">-p</samp> or <samp class="option">-r</samp> is supplied without a <var class="var">name</var> |
| argument, an attempt is made to remove a completion specification for |
| a <var class="var">name</var> for which no specification exists, or |
| an error occurs adding a completion specification. |
| </p> |
| </dd> |
| <dt><a id="index-compopt"></a><span><code class="code">compopt</code><a class="copiable-link" href="#index-compopt"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted"><code class="code">compopt</code> [-o <var class="var">option</var>] [-DEI] [+o <var class="var">option</var>] [<var class="var">name</var>] |
| </pre></div> |
| <p>Modify completion options for each <var class="var">name</var> according to the |
| <var class="var">option</var>s, or for the currently-executing completion if no <var class="var">name</var>s |
| are supplied. |
| If no <var class="var">option</var>s are given, display the completion options for each |
| <var class="var">name</var> or the current completion. |
| The possible values of <var class="var">option</var> are those valid for the <code class="code">complete</code> |
| builtin described above. |
| The <samp class="option">-D</samp> option indicates that other supplied options should |
| apply to the “default” command completion; that is, completion attempted |
| on a command for which no completion has previously been defined. |
| The <samp class="option">-E</samp> option indicates that other supplied options should |
| apply to “empty” command completion; that is, completion attempted on a |
| blank line. |
| The <samp class="option">-I</samp> option indicates that other supplied options should |
| apply to completion on the initial non-assignment word on the line, or after a |
| command delimiter such as ‘<samp class="samp">;</samp>’ or ‘<samp class="samp">|</samp>’, which is usually command |
| name completion. |
| </p> |
| <p>If multiple options are supplied, the <samp class="option">-D</samp> option takes precedence |
| over <samp class="option">-E</samp>, and both take precedence over <samp class="option">-I</samp> |
| </p> |
| <p>The return value is true unless an invalid option is supplied, an attempt |
| is made to modify the options for a <var class="var">name</var> for which no completion |
| specification exists, or an output error occurs. |
| </p> |
| </dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="section-level-extent" id="A-Programmable-Completion-Example"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Programmable-Completion-Builtins" accesskey="p" rel="prev">Programmable Completion Builtins</a>, Up: <a href="#Command-Line-Editing" accesskey="u" rel="up">Command Line Editing</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="A-Programmable-Completion-Example-1"><span>8.8 A Programmable Completion Example<a class="copiable-link" href="#A-Programmable-Completion-Example-1"> ¶</a></span></h3> |
| |
| <p>The most common way to obtain additional completion functionality beyond |
| the default actions <code class="code">complete</code> and <code class="code">compgen</code> provide is to use |
| a shell function and bind it to a particular command using <code class="code">complete -F</code>. |
| </p> |
| <p>The following function provides completions for the <code class="code">cd</code> builtin. |
| It is a reasonably good example of what shell functions must do when |
| used for completion. This function uses the word passed as <code class="code">$2</code> |
| to determine the directory name to complete. You can also use the |
| <code class="code">COMP_WORDS</code> array variable; the current word is indexed by the |
| <code class="code">COMP_CWORD</code> variable. |
| </p> |
| <p>The function relies on the <code class="code">complete</code> and <code class="code">compgen</code> builtins |
| to do much of the work, adding only the things that the Bash <code class="code">cd</code> |
| does beyond accepting basic directory names: |
| tilde expansion (see <a class="pxref" href="#Tilde-Expansion">Tilde Expansion</a>), |
| searching directories in <var class="var">$CDPATH</var>, which is described above |
| (see <a class="pxref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>), |
| and basic support for the <code class="code">cdable_vars</code> shell option |
| (see <a class="pxref" href="#The-Shopt-Builtin">The Shopt Builtin</a>). |
| <code class="code">_comp_cd</code> modifies the value of <var class="var">IFS</var> so that it contains only |
| a newline to accommodate file names containing spaces and tabs – |
| <code class="code">compgen</code> prints the possible completions it generates one per line. |
| </p> |
| <p>Possible completions go into the <var class="var">COMPREPLY</var> array variable, one |
| completion per array element. The programmable completion system retrieves |
| the completions from there when the function returns. |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted"># A completion function for the cd builtin |
| # based on the cd completion function from the bash_completion package |
| _comp_cd() |
| { |
| local IFS=$' \t\n' # normalize IFS |
| local cur _skipdot _cdpath |
| local i j k |
| |
| # Tilde expansion, which also expands tilde to full pathname |
| case "$2" in |
| \~*) eval cur="$2" ;; |
| *) cur=$2 ;; |
| esac |
| |
| # no cdpath or absolute pathname -- straight directory completion |
| if [[ -z "${CDPATH:-}" ]] || [[ "$cur" == @(./*|../*|/*) ]]; then |
| # compgen prints paths one per line; could also use while loop |
| IFS=$'\n' |
| COMPREPLY=( $(compgen -d -- "$cur") ) |
| IFS=$' \t\n' |
| # CDPATH+directories in the current directory if not in CDPATH |
| else |
| IFS=$'\n' |
| _skipdot=false |
| # preprocess CDPATH to convert null directory names to . |
| _cdpath=${CDPATH/#:/.:} |
| _cdpath=${_cdpath//::/:.:} |
| _cdpath=${_cdpath/%:/:.} |
| for i in ${_cdpath//:/$'\n'}; do |
| if [[ $i -ef . ]]; then _skipdot=true; fi |
| k="${#COMPREPLY[@]}" |
| for j in $( compgen -d -- "$i/$cur" ); do |
| COMPREPLY[k++]=${j#$i/} # cut off directory |
| done |
| done |
| $_skipdot || COMPREPLY+=( $(compgen -d -- "$cur") ) |
| IFS=$' \t\n' |
| fi |
| |
| # variable names if appropriate shell option set and no completions |
| if shopt -q cdable_vars && [[ ${#COMPREPLY[@]} -eq 0 ]]; then |
| COMPREPLY=( $(compgen -v -- "$cur") ) |
| fi |
| |
| return 0 |
| } |
| </pre></div> |
| |
| <p>We install the completion function using the <samp class="option">-F</samp> option to |
| <code class="code">complete</code>: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted"># Tell readline to quote appropriate and append slashes to directories; |
| # use the bash default completion for other arguments |
| complete -o filenames -o nospace -o bashdefault -F _comp_cd cd |
| </pre></div> |
| |
| <p>Since we’d like Bash and Readline to take care of some |
| of the other details for us, we use several other options to tell Bash |
| and Readline what to do. The <samp class="option">-o filenames</samp> option tells Readline |
| that the possible completions should be treated as filenames, and quoted |
| appropriately. That option will also cause Readline to append a slash to |
| filenames it can determine are directories (which is why we might want to |
| extend <code class="code">_comp_cd</code> to append a slash if we’re using directories found |
| via <var class="var">CDPATH</var>: Readline can’t tell those completions are directories). |
| The <samp class="option">-o nospace</samp> option tells Readline to not append a space |
| character to the directory name, in case we want to append to it. |
| The <samp class="option">-o bashdefault</samp> option brings in the rest of the "Bash default" |
| completions – possible completions that Bash adds to the default Readline |
| set. These include things like command name completion, variable completion |
| for words beginning with ‘<samp class="samp">$</samp>’ or ‘<samp class="samp">${</samp>’, completions containing pathname |
| expansion patterns (see <a class="pxref" href="#Filename-Expansion">Filename Expansion</a>), and so on. |
| </p> |
| <p>Once installed using <code class="code">complete</code>, <code class="code">_comp_cd</code> will be called every |
| time we attempt word completion for a <code class="code">cd</code> command. |
| </p> |
| <p>Many more examples – an extensive collection of completions for most of |
| the common GNU, Unix, and Linux commands – are available as part of the |
| bash_completion project. This is installed by default on many GNU/Linux |
| distributions. Originally written by Ian Macdonald, the project now lives |
| at <a class="url" href="https://github.com/scop/bash-completion/">https://github.com/scop/bash-completion/</a>. There are ports for |
| other systems such as Solaris and Mac OS X. |
| </p> |
| <p>An older version of the bash_completion package is distributed with bash |
| in the <samp class="file">examples/complete</samp> subdirectory. |
| </p> |
| <a class="index-entry-id" id="index-History_002c-how-to-use"></a> |
| |
| <hr> |
| </div> |
| </div> |
| <div class="chapter-level-extent" id="Using-History-Interactively"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Installing-Bash" accesskey="n" rel="next">Installing Bash</a>, Previous: <a href="#Command-Line-Editing" accesskey="p" rel="prev">Command Line Editing</a>, Up: <a href="#Top" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h2 class="chapter" id="Using-History-Interactively-1"><span>9 Using History Interactively<a class="copiable-link" href="#Using-History-Interactively-1"> ¶</a></span></h2> |
| |
| |
| <p>This chapter describes how to use the <small class="sc">GNU</small> History Library |
| interactively, from a user’s standpoint. |
| It should be considered a user’s guide. |
| For information on using the <small class="sc">GNU</small> History Library in other programs, |
| see the <small class="sc">GNU</small> Readline Library Manual. |
| </p> |
| |
| <ul class="mini-toc"> |
| <li><a href="#Bash-History-Facilities" accesskey="1">Bash History Facilities</a></li> |
| <li><a href="#Bash-History-Builtins" accesskey="2">Bash History Builtins</a></li> |
| <li><a href="#History-Interaction" accesskey="3">History Expansion</a></li> |
| </ul> |
| <hr> |
| <div class="section-level-extent" id="Bash-History-Facilities"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Bash-History-Builtins" accesskey="n" rel="next">Bash History Builtins</a>, Up: <a href="#Using-History-Interactively" accesskey="u" rel="up">Using History Interactively</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Bash-History-Facilities-1"><span>9.1 Bash History Facilities<a class="copiable-link" href="#Bash-History-Facilities-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-command-history"></a> |
| <a class="index-entry-id" id="index-history-list"></a> |
| |
| <p>When the <samp class="option">-o history</samp> option to the <code class="code">set</code> builtin |
| is enabled (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>), |
| the shell provides access to the <em class="dfn">command history</em>, |
| the list of commands previously typed. |
| The value of the <code class="env">HISTSIZE</code> shell variable is used as the |
| number of commands to save in a history list. |
| The text of the last <code class="env">$HISTSIZE</code> |
| commands (default 500) is saved. |
| The shell stores each command in the history list prior to |
| parameter and variable expansion |
| but after history expansion is performed, subject to the |
| values of the shell variables |
| <code class="env">HISTIGNORE</code> and <code class="env">HISTCONTROL</code>. |
| </p> |
| <p>When the shell starts up, the history is initialized from the |
| file named by the <code class="env">HISTFILE</code> variable (default <samp class="file">~/.bash_history</samp>). |
| The file named by the value of <code class="env">HISTFILE</code> is truncated, if |
| necessary, to contain no more than the number of lines specified by |
| the value of the <code class="env">HISTFILESIZE</code> variable. |
| When a shell with history enabled exits, the last |
| <code class="env">$HISTSIZE</code> lines are copied from the history list to the file |
| named by <code class="env">$HISTFILE</code>. |
| If the <code class="code">histappend</code> shell option is set (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>), |
| the lines are appended to the history file, |
| otherwise the history file is overwritten. |
| If <code class="env">HISTFILE</code> |
| is unset, or if the history file is unwritable, the history is not saved. |
| After saving the history, the history file is truncated |
| to contain no more than <code class="env">$HISTFILESIZE</code> lines. |
| If <code class="env">HISTFILESIZE</code> is unset, or set to null, a non-numeric value, or |
| a numeric value less than zero, the history file is not truncated. |
| </p> |
| <p>If the <code class="env">HISTTIMEFORMAT</code> is set, the time stamp information |
| associated with each history entry is written to the history file, |
| marked with the history comment character. |
| When the history file is read, lines beginning with the history |
| comment character followed immediately by a digit are interpreted |
| as timestamps for the following history entry. |
| </p> |
| <p>The builtin command <code class="code">fc</code> may be used to list or edit and re-execute |
| a portion of the history list. |
| The <code class="code">history</code> builtin may be used to display or modify the history |
| list and manipulate the history file. |
| When using command-line editing, search commands |
| are available in each editing mode that provide access to the |
| history list (see <a class="pxref" href="#Commands-For-History">Commands For Manipulating The History</a>). |
| </p> |
| <p>The shell allows control over which commands are saved on the history |
| list. The <code class="env">HISTCONTROL</code> and <code class="env">HISTIGNORE</code> |
| variables may be set to cause the shell to save only a subset of the |
| commands entered. |
| The <code class="code">cmdhist</code> |
| shell option, if enabled, causes the shell to attempt to save each |
| line of a multi-line command in the same history entry, adding |
| semicolons where necessary to preserve syntactic correctness. |
| The <code class="code">lithist</code> |
| shell option causes the shell to save the command with embedded newlines |
| instead of semicolons. |
| The <code class="code">shopt</code> builtin is used to set these options. |
| See <a class="xref" href="#The-Shopt-Builtin">The Shopt Builtin</a>, for a description of <code class="code">shopt</code>. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Bash-History-Builtins"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#History-Interaction" accesskey="n" rel="next">History Expansion</a>, Previous: <a href="#Bash-History-Facilities" accesskey="p" rel="prev">Bash History Facilities</a>, Up: <a href="#Using-History-Interactively" accesskey="u" rel="up">Using History Interactively</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Bash-History-Builtins-1"><span>9.2 Bash History Builtins<a class="copiable-link" href="#Bash-History-Builtins-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-history-builtins"></a> |
| |
| <p>Bash provides two builtin commands which manipulate the |
| history list and history file. |
| </p> |
| <dl class="table"> |
| <dt><a id="index-fc"></a><span><code class="code">fc</code><a class="copiable-link" href="#index-fc"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted"><code class="code">fc [-e <var class="var">ename</var>] [-lnr] [<var class="var">first</var>] [<var class="var">last</var>]</code> |
| <code class="code">fc -s [<var class="var">pat</var>=<var class="var">rep</var>] [<var class="var">command</var>]</code> |
| </pre></div> |
| |
| <p>The first form selects a range of commands from <var class="var">first</var> to |
| <var class="var">last</var> from the history list and displays or edits and re-executes |
| them. |
| Both <var class="var">first</var> and |
| <var class="var">last</var> may be specified as a string (to locate the most recent |
| command beginning with that string) or as a number (an index into the |
| history list, where a negative number is used as an offset from the |
| current command number). |
| </p> |
| <p>When listing, a <var class="var">first</var> or <var class="var">last</var> of 0 is equivalent to -1 |
| and -0 is equivalent to the current command (usually the <code class="code">fc</code> |
| command); |
| otherwise 0 is equivalent to -1 and -0 is invalid. |
| </p> |
| <p>If <var class="var">last</var> is not specified, it is set to |
| <var class="var">first</var>. If <var class="var">first</var> is not specified, it is set to the previous |
| command for editing and −16 for listing. If the <samp class="option">-l</samp> flag is |
| given, the commands are listed on standard output. The <samp class="option">-n</samp> flag |
| suppresses the command numbers when listing. The <samp class="option">-r</samp> flag |
| reverses the order of the listing. Otherwise, the editor given by |
| <var class="var">ename</var> is invoked on a file containing those commands. If |
| <var class="var">ename</var> is not given, the value of the following variable expansion |
| is used: <code class="code">${FCEDIT:-${EDITOR:-vi}}</code>. This says to use the |
| value of the <code class="env">FCEDIT</code> variable if set, or the value of the |
| <code class="env">EDITOR</code> variable if that is set, or <code class="code">vi</code> if neither is set. |
| When editing is complete, the edited commands are echoed and executed. |
| </p> |
| <p>In the second form, <var class="var">command</var> is re-executed after each instance |
| of <var class="var">pat</var> in the selected command is replaced by <var class="var">rep</var>. |
| <var class="var">command</var> is interpreted the same as <var class="var">first</var> above. |
| </p> |
| <p>A useful alias to use with the <code class="code">fc</code> command is <code class="code">r='fc -s'</code>, so |
| that typing ‘<samp class="samp">r cc</samp>’ runs the last command beginning with <code class="code">cc</code> |
| and typing ‘<samp class="samp">r</samp>’ re-executes the last command (see <a class="pxref" href="#Aliases">Aliases</a>). |
| </p> |
| </dd> |
| <dt><a id="index-history"></a><span><code class="code">history</code><a class="copiable-link" href="#index-history"> ¶</a></span></dt> |
| <dd><div class="example"> |
| <pre class="example-preformatted">history [<var class="var">n</var>] |
| history -c |
| history -d <var class="var">offset</var> |
| history -d <var class="var">start</var>-<var class="var">end</var> |
| history [-anrw] [<var class="var">filename</var>] |
| history -ps <var class="var">arg</var> |
| </pre></div> |
| |
| <p>With no options, display the history list with line numbers. |
| Lines prefixed with a ‘<samp class="samp">*</samp>’ have been modified. |
| An argument of <var class="var">n</var> lists only the last <var class="var">n</var> lines. |
| If the shell variable <code class="env">HISTTIMEFORMAT</code> is set and not null, |
| it is used as a format string for <var class="var">strftime</var> to display |
| the time stamp associated with each displayed history entry. |
| No intervening blank is printed between the formatted time stamp |
| and the history line. |
| </p> |
| <p>Options, if supplied, have the following meanings: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">-c</code></dt> |
| <dd><p>Clear the history list. This may be combined |
| with the other options to replace the history list completely. |
| </p> |
| </dd> |
| <dt><code class="code">-d <var class="var">offset</var></code></dt> |
| <dd><p>Delete the history entry at position <var class="var">offset</var>. |
| If <var class="var">offset</var> is positive, it should be specified as it appears when |
| the history is displayed. |
| If <var class="var">offset</var> is negative, it is interpreted as relative to one greater |
| than the last history position, so negative indices count back from the |
| end of the history, and an index of ‘<samp class="samp">-1</samp>’ refers to the current |
| <code class="code">history -d</code> command. |
| </p> |
| </dd> |
| <dt><code class="code">-d <var class="var">start</var>-<var class="var">end</var></code></dt> |
| <dd><p>Delete the range of history entries between positions <var class="var">start</var> and |
| <var class="var">end</var>, inclusive. |
| Positive and negative values for <var class="var">start</var> and <var class="var">end</var> |
| are interpreted as described above. |
| </p> |
| </dd> |
| <dt><code class="code">-a</code></dt> |
| <dd><p>Append the new history lines to the history file. |
| These are history lines entered since the beginning of the current |
| Bash session, but not already appended to the history file. |
| </p> |
| </dd> |
| <dt><code class="code">-n</code></dt> |
| <dd><p>Append the history lines not already read from the history file |
| to the current history list. These are lines appended to the history |
| file since the beginning of the current Bash session. |
| </p> |
| </dd> |
| <dt><code class="code">-r</code></dt> |
| <dd><p>Read the history file and append its contents to |
| the history list. |
| </p> |
| </dd> |
| <dt><code class="code">-w</code></dt> |
| <dd><p>Write out the current history list to the history file. |
| </p> |
| </dd> |
| <dt><code class="code">-p</code></dt> |
| <dd><p>Perform history substitution on the <var class="var">arg</var>s and display the result |
| on the standard output, without storing the results in the history list. |
| </p> |
| </dd> |
| <dt><code class="code">-s</code></dt> |
| <dd><p>The <var class="var">arg</var>s are added to the end of |
| the history list as a single entry. |
| </p> |
| </dd> |
| </dl> |
| |
| <p>If a <var class="var">filename</var> argument is supplied |
| when any of the <samp class="option">-w</samp>, <samp class="option">-r</samp>, <samp class="option">-a</samp>, or <samp class="option">-n</samp> options |
| is used, Bash uses <var class="var">filename</var> as the history file. |
| If not, then the value of the <code class="env">HISTFILE</code> variable is used. |
| </p> |
| <p>The return value is 0 unless an invalid option is encountered, an |
| error occurs while reading or writing the history file, an invalid |
| <var class="var">offset</var> or range is supplied as an argument to <samp class="option">-d</samp>, or the |
| history expansion supplied as an argument to <samp class="option">-p</samp> fails. |
| </p> |
| </dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="section-level-extent" id="History-Interaction"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Bash-History-Builtins" accesskey="p" rel="prev">Bash History Builtins</a>, Up: <a href="#Using-History-Interactively" accesskey="u" rel="up">Using History Interactively</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="History-Expansion"><span>9.3 History Expansion<a class="copiable-link" href="#History-Expansion"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-history-expansion"></a> |
| |
| <p>The History library provides a history expansion feature that is similar |
| to the history expansion provided by <code class="code">csh</code>. This section |
| describes the syntax used to manipulate the history information. |
| </p> |
| <p>History expansions introduce words from the history list into |
| the input stream, making it easy to repeat commands, insert the |
| arguments to a previous command into the current input line, or |
| fix errors in previous commands quickly. |
| </p> |
| <p>History expansion is performed immediately after a complete line |
| is read, before the shell breaks it into words, and is performed |
| on each line individually. Bash attempts to inform the history |
| expansion functions about quoting still in effect from previous lines. |
| </p> |
| <p>History expansion takes place in two parts. The first is to determine |
| which line from the history list should be used during substitution. |
| The second is to select portions of that line for inclusion into the |
| current one. The line selected from the history is called the |
| <em class="dfn">event</em>, and the portions of that line that are acted upon are |
| called <em class="dfn">words</em>. Various <em class="dfn">modifiers</em> are available to manipulate |
| the selected words. The line is broken into words in the same fashion |
| that Bash does, so that several words |
| surrounded by quotes are considered one word. |
| History expansions are introduced by the appearance of the |
| history expansion character, which is ‘<samp class="samp">!</samp>’ by default. |
| </p> |
| <p>History expansion implements shell-like quoting conventions: |
| a backslash can be used to remove the special handling for the next character; |
| single quotes enclose verbatim sequences of characters, and can be used to |
| inhibit history expansion; |
| and characters enclosed within double quotes may be subject to history |
| expansion, since backslash can escape the history expansion character, |
| but single quotes may not, since they are not treated specially within |
| double quotes. |
| </p> |
| <p>When using the shell, only ‘<samp class="samp">\</samp>’ and ‘<samp class="samp">'</samp>’ may be used to escape the |
| history expansion character, but the history expansion character is |
| also treated as quoted if it immediately precedes the closing double quote |
| in a double-quoted string. |
| </p> |
| <p>Several shell options settable with the <code class="code">shopt</code> |
| builtin (see <a class="pxref" href="#The-Shopt-Builtin">The Shopt Builtin</a>) may be used to tailor |
| the behavior of history expansion. If the |
| <code class="code">histverify</code> shell option is enabled, and Readline |
| is being used, history substitutions are not immediately passed to |
| the shell parser. |
| Instead, the expanded line is reloaded into the Readline |
| editing buffer for further modification. |
| If Readline is being used, and the <code class="code">histreedit</code> |
| shell option is enabled, a failed history expansion will be |
| reloaded into the Readline editing buffer for correction. |
| The <samp class="option">-p</samp> option to the <code class="code">history</code> builtin command |
| may be used to see what a history expansion will do before using it. |
| The <samp class="option">-s</samp> option to the <code class="code">history</code> builtin may be used to |
| add commands to the end of the history list without actually executing |
| them, so that they are available for subsequent recall. |
| This is most useful in conjunction with Readline. |
| </p> |
| <p>The shell allows control of the various characters used by the |
| history expansion mechanism with the <code class="code">histchars</code> variable, |
| as explained above (see <a class="pxref" href="#Bash-Variables">Bash Variables</a>). The shell uses |
| the history comment character to mark history timestamps when |
| writing the history file. |
| </p> |
| |
| <ul class="mini-toc"> |
| <li><a href="#Event-Designators" accesskey="1">Event Designators</a></li> |
| <li><a href="#Word-Designators" accesskey="2">Word Designators</a></li> |
| <li><a href="#Modifiers" accesskey="3">Modifiers</a></li> |
| </ul> |
| <hr> |
| <div class="subsection-level-extent" id="Event-Designators"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Word-Designators" accesskey="n" rel="next">Word Designators</a>, Up: <a href="#History-Interaction" accesskey="u" rel="up">History Expansion</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Event-Designators-1"><span>9.3.1 Event Designators<a class="copiable-link" href="#Event-Designators-1"> ¶</a></span></h4> |
| <a class="index-entry-id" id="index-event-designators"></a> |
| |
| <p>An event designator is a reference to a command line entry in the |
| history list. |
| Unless the reference is absolute, events are relative to the current |
| position in the history list. |
| <a class="index-entry-id" id="index-history-events"></a> |
| </p> |
| <dl class="table"> |
| <dt><code class="code">!</code></dt> |
| <dd><p>Start a history substitution, except when followed by a space, tab, |
| the end of the line, ‘<samp class="samp">=</samp>’ or ‘<samp class="samp">(</samp>’ (when the |
| <code class="code">extglob</code> shell option is enabled using the <code class="code">shopt</code> builtin). |
| </p> |
| </dd> |
| <dt><code class="code">!<var class="var">n</var></code></dt> |
| <dd><p>Refer to command line <var class="var">n</var>. |
| </p> |
| </dd> |
| <dt><code class="code">!-<var class="var">n</var></code></dt> |
| <dd><p>Refer to the command <var class="var">n</var> lines back. |
| </p> |
| </dd> |
| <dt><code class="code">!!</code></dt> |
| <dd><p>Refer to the previous command. This is a synonym for ‘<samp class="samp">!-1</samp>’. |
| </p> |
| </dd> |
| <dt><code class="code">!<var class="var">string</var></code></dt> |
| <dd><p>Refer to the most recent command |
| preceding the current position in the history list |
| starting with <var class="var">string</var>. |
| </p> |
| </dd> |
| <dt><code class="code">!?<var class="var">string</var>[?]</code></dt> |
| <dd><p>Refer to the most recent command |
| preceding the current position in the history list |
| containing <var class="var">string</var>. |
| The trailing |
| ‘<samp class="samp">?</samp>’ may be omitted if the <var class="var">string</var> is followed immediately by |
| a newline. |
| If <var class="var">string</var> is missing, the string from the most recent search is used; |
| it is an error if there is no previous search string. |
| </p> |
| </dd> |
| <dt><code class="code">^<var class="var">string1</var>^<var class="var">string2</var>^</code></dt> |
| <dd><p>Quick Substitution. Repeat the last command, replacing <var class="var">string1</var> |
| with <var class="var">string2</var>. Equivalent to |
| <code class="code">!!:s^<var class="var">string1</var>^<var class="var">string2</var>^</code>. |
| </p> |
| </dd> |
| <dt><code class="code">!#</code></dt> |
| <dd><p>The entire command line typed so far. |
| </p> |
| </dd> |
| </dl> |
| |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Word-Designators"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Modifiers" accesskey="n" rel="next">Modifiers</a>, Previous: <a href="#Event-Designators" accesskey="p" rel="prev">Event Designators</a>, Up: <a href="#History-Interaction" accesskey="u" rel="up">History Expansion</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Word-Designators-1"><span>9.3.2 Word Designators<a class="copiable-link" href="#Word-Designators-1"> ¶</a></span></h4> |
| |
| <p>Word designators are used to select desired words from the event. |
| A ‘<samp class="samp">:</samp>’ separates the event specification from the word designator. It |
| may be omitted if the word designator begins with a ‘<samp class="samp">^</samp>’, ‘<samp class="samp">$</samp>’, |
| ‘<samp class="samp">*</samp>’, ‘<samp class="samp">-</samp>’, or ‘<samp class="samp">%</samp>’. Words are numbered from the beginning |
| of the line, with the first word being denoted by 0 (zero). Words are |
| inserted into the current line separated by single spaces. |
| </p> |
| <p>For example, |
| </p> |
| <dl class="table"> |
| <dt><code class="code">!!</code></dt> |
| <dd><p>designates the preceding command. When you type this, the preceding |
| command is repeated in toto. |
| </p> |
| </dd> |
| <dt><code class="code">!!:$</code></dt> |
| <dd><p>designates the last argument of the preceding command. This may be |
| shortened to <code class="code">!$</code>. |
| </p> |
| </dd> |
| <dt><code class="code">!fi:2</code></dt> |
| <dd><p>designates the second argument of the most recent command starting with |
| the letters <code class="code">fi</code>. |
| </p></dd> |
| </dl> |
| |
| <p>Here are the word designators: |
| </p> |
| <dl class="table"> |
| <dt><code class="code">0 (zero)</code></dt> |
| <dd><p>The <code class="code">0</code>th word. For many applications, this is the command word. |
| </p> |
| </dd> |
| <dt><code class="code"><var class="var">n</var></code></dt> |
| <dd><p>The <var class="var">n</var>th word. |
| </p> |
| </dd> |
| <dt><code class="code">^</code></dt> |
| <dd><p>The first argument; that is, word 1. |
| </p> |
| </dd> |
| <dt><code class="code">$</code></dt> |
| <dd><p>The last argument. |
| </p> |
| </dd> |
| <dt><code class="code">%</code></dt> |
| <dd><p>The first word matched by the most recent ‘<samp class="samp">?<var class="var">string</var>?</samp>’ search, |
| if the search string begins with a character that is part of a word. |
| </p> |
| </dd> |
| <dt><code class="code"><var class="var">x</var>-<var class="var">y</var></code></dt> |
| <dd><p>A range of words; ‘<samp class="samp">-<var class="var">y</var></samp>’ abbreviates ‘<samp class="samp">0-<var class="var">y</var></samp>’. |
| </p> |
| </dd> |
| <dt><code class="code">*</code></dt> |
| <dd><p>All of the words, except the <code class="code">0</code>th. This is a synonym for ‘<samp class="samp">1-$</samp>’. |
| It is not an error to use ‘<samp class="samp">*</samp>’ if there is just one word in the event; |
| the empty string is returned in that case. |
| </p> |
| </dd> |
| <dt><code class="code"><var class="var">x</var>*</code></dt> |
| <dd><p>Abbreviates ‘<samp class="samp"><var class="var">x</var>-$</samp>’ |
| </p> |
| </dd> |
| <dt><code class="code"><var class="var">x</var>-</code></dt> |
| <dd><p>Abbreviates ‘<samp class="samp"><var class="var">x</var>-$</samp>’ like ‘<samp class="samp"><var class="var">x</var>*</samp>’, but omits the last word. |
| If ‘<samp class="samp">x</samp>’ is missing, it defaults to 0. |
| </p> |
| </dd> |
| </dl> |
| |
| <p>If a word designator is supplied without an event specification, the |
| previous command is used as the event. |
| </p> |
| <hr> |
| </div> |
| <div class="subsection-level-extent" id="Modifiers"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Word-Designators" accesskey="p" rel="prev">Word Designators</a>, Up: <a href="#History-Interaction" accesskey="u" rel="up">History Expansion</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h4 class="subsection" id="Modifiers-1"><span>9.3.3 Modifiers<a class="copiable-link" href="#Modifiers-1"> ¶</a></span></h4> |
| |
| <p>After the optional word designator, you can add a sequence of one or more |
| of the following modifiers, each preceded by a ‘<samp class="samp">:</samp>’. |
| These modify, or edit, the word or words selected from the history event. |
| </p> |
| <dl class="table"> |
| <dt><code class="code">h</code></dt> |
| <dd><p>Remove a trailing pathname component, leaving only the head. |
| </p> |
| </dd> |
| <dt><code class="code">t</code></dt> |
| <dd><p>Remove all leading pathname components, leaving the tail. |
| </p> |
| </dd> |
| <dt><code class="code">r</code></dt> |
| <dd><p>Remove a trailing suffix of the form ‘<samp class="samp">.<var class="var">suffix</var></samp>’, leaving |
| the basename. |
| </p> |
| </dd> |
| <dt><code class="code">e</code></dt> |
| <dd><p>Remove all but the trailing suffix. |
| </p> |
| </dd> |
| <dt><code class="code">p</code></dt> |
| <dd><p>Print the new command but do not execute it. |
| </p> |
| </dd> |
| <dt><code class="code">q</code></dt> |
| <dd><p>Quote the substituted words, escaping further substitutions. |
| </p> |
| </dd> |
| <dt><code class="code">x</code></dt> |
| <dd><p>Quote the substituted words as with ‘<samp class="samp">q</samp>’, |
| but break into words at spaces, tabs, and newlines. |
| The ‘<samp class="samp">q</samp>’ and ‘<samp class="samp">x</samp>’ modifiers are mutually exclusive; the last one |
| supplied is used. |
| </p> |
| </dd> |
| <dt><code class="code">s/<var class="var">old</var>/<var class="var">new</var>/</code></dt> |
| <dd><p>Substitute <var class="var">new</var> for the first occurrence of <var class="var">old</var> in the |
| event line. |
| Any character may be used as the delimiter in place of ‘<samp class="samp">/</samp>’. |
| The delimiter may be quoted in <var class="var">old</var> and <var class="var">new</var> |
| with a single backslash. If ‘<samp class="samp">&</samp>’ appears in <var class="var">new</var>, |
| it is replaced by <var class="var">old</var>. A single backslash will quote |
| the ‘<samp class="samp">&</samp>’. |
| If <var class="var">old</var> is null, it is set to the last <var class="var">old</var> |
| substituted, or, if no previous history substitutions took place, |
| the last <var class="var">string</var> |
| in a !?<var class="var">string</var><code class="code">[?]</code> |
| search. |
| If <var class="var">new</var> is null, each matching <var class="var">old</var> is deleted. |
| The final delimiter is optional if it is the last |
| character on the input line. |
| </p> |
| </dd> |
| <dt><code class="code">&</code></dt> |
| <dd><p>Repeat the previous substitution. |
| </p> |
| </dd> |
| <dt><code class="code">g</code></dt> |
| <dt><code class="code">a</code></dt> |
| <dd><p>Cause changes to be applied over the entire event line. Used in |
| conjunction with ‘<samp class="samp">s</samp>’, as in <code class="code">gs/<var class="var">old</var>/<var class="var">new</var>/</code>, |
| or with ‘<samp class="samp">&</samp>’. |
| </p> |
| </dd> |
| <dt><code class="code">G</code></dt> |
| <dd><p>Apply the following ‘<samp class="samp">s</samp>’ or ‘<samp class="samp">&</samp>’ modifier once to each word |
| in the event. |
| </p> |
| </dd> |
| </dl> |
| |
| <hr> |
| </div> |
| </div> |
| </div> |
| <div class="chapter-level-extent" id="Installing-Bash"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Reporting-Bugs" accesskey="n" rel="next">Reporting Bugs</a>, Previous: <a href="#Using-History-Interactively" accesskey="p" rel="prev">Using History Interactively</a>, Up: <a href="#Top" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h2 class="chapter" id="Installing-Bash-1"><span>10 Installing Bash<a class="copiable-link" href="#Installing-Bash-1"> ¶</a></span></h2> |
| |
| <p>This chapter provides basic instructions for installing Bash on |
| the various supported platforms. The distribution supports the |
| <small class="sc">GNU</small> operating systems, nearly every version of Unix, and several |
| non-Unix systems such as BeOS and Interix. |
| Other independent ports exist for |
| <small class="sc">MS-DOS</small>, <small class="sc">OS/2</small>, and Windows platforms. |
| </p> |
| |
| <ul class="mini-toc"> |
| <li><a href="#Basic-Installation" accesskey="1">Basic Installation</a></li> |
| <li><a href="#Compilers-and-Options" accesskey="2">Compilers and Options</a></li> |
| <li><a href="#Compiling-For-Multiple-Architectures" accesskey="3">Compiling For Multiple Architectures</a></li> |
| <li><a href="#Installation-Names" accesskey="4">Installation Names</a></li> |
| <li><a href="#Specifying-the-System-Type" accesskey="5">Specifying the System Type</a></li> |
| <li><a href="#Sharing-Defaults" accesskey="6">Sharing Defaults</a></li> |
| <li><a href="#Operation-Controls" accesskey="7">Operation Controls</a></li> |
| <li><a href="#Optional-Features" accesskey="8">Optional Features</a></li> |
| </ul> |
| <hr> |
| <div class="section-level-extent" id="Basic-Installation"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Compilers-and-Options" accesskey="n" rel="next">Compilers and Options</a>, Up: <a href="#Installing-Bash" accesskey="u" rel="up">Installing Bash</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Basic-Installation-1"><span>10.1 Basic Installation<a class="copiable-link" href="#Basic-Installation-1"> ¶</a></span></h3> |
| <a class="index-entry-id" id="index-installation"></a> |
| <a class="index-entry-id" id="index-configuration"></a> |
| <a class="index-entry-id" id="index-Bash-installation"></a> |
| <a class="index-entry-id" id="index-Bash-configuration"></a> |
| |
| <p>These are installation instructions for Bash. |
| </p> |
| <p>The simplest way to compile Bash is: |
| </p> |
| <ol class="enumerate"> |
| <li> <code class="code">cd</code> to the directory containing the source code and type |
| ‘<samp class="samp">./configure</samp>’ to configure Bash for your system. If you’re |
| using <code class="code">csh</code> on an old version of System V, you might need to |
| type ‘<samp class="samp">sh ./configure</samp>’ instead to prevent <code class="code">csh</code> from trying |
| to execute <code class="code">configure</code> itself. |
| |
| <p>Running <code class="code">configure</code> takes some time. |
| While running, it prints messages telling which features it is |
| checking for. |
| </p> |
| </li><li> Type ‘<samp class="samp">make</samp>’ to compile Bash and build the <code class="code">bashbug</code> bug |
| reporting script. |
| |
| </li><li> Optionally, type ‘<samp class="samp">make tests</samp>’ to run the Bash test suite. |
| |
| </li><li> Type ‘<samp class="samp">make install</samp>’ to install <code class="code">bash</code> and <code class="code">bashbug</code>. |
| This will also install the manual pages and Info file, message translation |
| files, some supplemental documentation, a number of example loadable |
| builtin commands, and a set of header files for developing loadable |
| builtins. |
| You may need additional privileges to install <code class="code">bash</code> to your |
| desired destination, so ‘<samp class="samp">sudo make install</samp>’ might be required. |
| More information about controlling the locations where <code class="code">bash</code> and |
| other files are installed is below (see <a class="pxref" href="#Installation-Names">Installation Names</a>). |
| |
| </li></ol> |
| |
| <p>The <code class="code">configure</code> shell script attempts to guess correct |
| values for various system-dependent variables used during |
| compilation. It uses those values to create a <samp class="file">Makefile</samp> in |
| each directory of the package (the top directory, the |
| <samp class="file">builtins</samp>, <samp class="file">doc</samp>, <samp class="file">po</samp>, and <samp class="file">support</samp> directories, |
| each directory under <samp class="file">lib</samp>, and several others). It also creates a |
| <samp class="file">config.h</samp> file containing system-dependent definitions. |
| Finally, it creates a shell script named <code class="code">config.status</code> that you |
| can run in the future to recreate the current configuration, a |
| file <samp class="file">config.cache</samp> that saves the results of its tests to |
| speed up reconfiguring, and a file <samp class="file">config.log</samp> containing |
| compiler output (useful mainly for debugging <code class="code">configure</code>). |
| If at some point |
| <samp class="file">config.cache</samp> contains results you don’t want to keep, you |
| may remove or edit it. |
| </p> |
| <p>To find out more about the options and arguments that the |
| <code class="code">configure</code> script understands, type |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">bash-4.2$ ./configure --help |
| </pre></div> |
| |
| <p>at the Bash prompt in your Bash source directory. |
| </p> |
| <p>If you want to build Bash in a directory separate from the source |
| directory – to build for multiple architectures, for example – |
| just use the full path to the configure script. The following commands |
| will build bash in a directory under <samp class="file">/usr/local/build</samp> from |
| the source code in <samp class="file">/usr/local/src/bash-4.4</samp>: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">mkdir /usr/local/build/bash-4.4 |
| cd /usr/local/build/bash-4.4 |
| bash /usr/local/src/bash-4.4/configure |
| make |
| </pre></div> |
| |
| <p>See <a class="ref" href="#Compiling-For-Multiple-Architectures">Compiling For Multiple Architectures</a> for more information |
| about building in a directory separate from the source. |
| </p> |
| <p>If you need to do unusual things to compile Bash, please |
| try to figure out how <code class="code">configure</code> could check whether or not |
| to do them, and mail diffs or instructions to |
| <a class="email" href="mailto:bash-maintainers@gnu.org">bash-maintainers@gnu.org</a> so they can be |
| considered for the next release. |
| </p> |
| <p>The file <samp class="file">configure.ac</samp> is used to create <code class="code">configure</code> |
| by a program called Autoconf. |
| You only need <samp class="file">configure.ac</samp> if you want to change it or regenerate |
| <code class="code">configure</code> using a newer version of Autoconf. |
| If you do this, make sure you are using Autoconf version 2.69 or |
| newer. |
| </p> |
| <p>You can remove the program binaries and object files from the |
| source code directory by typing ‘<samp class="samp">make clean</samp>’. To also remove the |
| files that <code class="code">configure</code> created (so you can compile Bash for |
| a different kind of computer), type ‘<samp class="samp">make distclean</samp>’. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Compilers-and-Options"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Compiling-For-Multiple-Architectures" accesskey="n" rel="next">Compiling For Multiple Architectures</a>, Previous: <a href="#Basic-Installation" accesskey="p" rel="prev">Basic Installation</a>, Up: <a href="#Installing-Bash" accesskey="u" rel="up">Installing Bash</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Compilers-and-Options-1"><span>10.2 Compilers and Options<a class="copiable-link" href="#Compilers-and-Options-1"> ¶</a></span></h3> |
| |
| <p>Some systems require unusual options for compilation or linking |
| that the <code class="code">configure</code> script does not know about. You can |
| give <code class="code">configure</code> initial values for variables by setting |
| them in the environment. Using a Bourne-compatible shell, you |
| can do that on the command line like this: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">CC=c89 CFLAGS=-O2 LIBS=-lposix ./configure |
| </pre></div> |
| |
| <p>On systems that have the <code class="code">env</code> program, you can do it like this: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">env CPPFLAGS=-I/usr/local/include LDFLAGS=-s ./configure |
| </pre></div> |
| |
| <p>The configuration process uses GCC to build Bash if it |
| is available. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Compiling-For-Multiple-Architectures"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Installation-Names" accesskey="n" rel="next">Installation Names</a>, Previous: <a href="#Compilers-and-Options" accesskey="p" rel="prev">Compilers and Options</a>, Up: <a href="#Installing-Bash" accesskey="u" rel="up">Installing Bash</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Compiling-For-Multiple-Architectures-1"><span>10.3 Compiling For Multiple Architectures<a class="copiable-link" href="#Compiling-For-Multiple-Architectures-1"> ¶</a></span></h3> |
| |
| <p>You can compile Bash for more than one kind of computer at the |
| same time, by placing the object files for each architecture in their |
| own directory. To do this, you must use a version of <code class="code">make</code> that |
| supports the <code class="code">VPATH</code> variable, such as GNU <code class="code">make</code>. |
| <code class="code">cd</code> to the |
| directory where you want the object files and executables to go and run |
| the <code class="code">configure</code> script from the source directory |
| (see <a class="pxref" href="#Basic-Installation">Basic Installation</a>). |
| You may need to |
| supply the <samp class="option">--srcdir=PATH</samp> argument to tell <code class="code">configure</code> where the |
| source files are. <code class="code">configure</code> automatically checks for the |
| source code in the directory that <code class="code">configure</code> is in and in ‘..’. |
| </p> |
| <p>If you have to use a <code class="code">make</code> that does not support the <code class="code">VPATH</code> |
| variable, you can compile Bash for one architecture at a |
| time in the source code directory. After you have installed |
| Bash for one architecture, use ‘<samp class="samp">make distclean</samp>’ before |
| reconfiguring for another architecture. |
| </p> |
| <p>Alternatively, if your system supports symbolic links, you can use the |
| <samp class="file">support/mkclone</samp> script to create a build tree which has |
| symbolic links back to each file in the source directory. Here’s an |
| example that creates a build directory in the current directory from a |
| source directory <samp class="file">/usr/gnu/src/bash-2.0</samp>: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">bash /usr/gnu/src/bash-2.0/support/mkclone -s /usr/gnu/src/bash-2.0 . |
| </pre></div> |
| |
| <p>The <code class="code">mkclone</code> script requires Bash, so you must have already built |
| Bash for at least one architecture before you can create build |
| directories for other architectures. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Installation-Names"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Specifying-the-System-Type" accesskey="n" rel="next">Specifying the System Type</a>, Previous: <a href="#Compiling-For-Multiple-Architectures" accesskey="p" rel="prev">Compiling For Multiple Architectures</a>, Up: <a href="#Installing-Bash" accesskey="u" rel="up">Installing Bash</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Installation-Names-1"><span>10.4 Installation Names<a class="copiable-link" href="#Installation-Names-1"> ¶</a></span></h3> |
| |
| <p>By default, ‘<samp class="samp">make install</samp>’ will install into |
| <samp class="file">/usr/local/bin</samp>, <samp class="file">/usr/local/man</samp>, etc.; |
| that is, the <em class="dfn">installation prefix</em> defaults to <samp class="file">/usr/local</samp>. |
| You can specify an installation prefix other than <samp class="file">/usr/local</samp> by |
| giving <code class="code">configure</code> the option <samp class="option">--prefix=<var class="var">PATH</var></samp>, |
| or by specifying a value for the <code class="env">prefix</code> ‘<samp class="samp">make</samp>’ |
| variable when running ‘<samp class="samp">make install</samp>’ |
| (e.g., ‘<samp class="samp">make install prefix=<var class="var">PATH</var></samp>’). |
| The <code class="env">prefix</code> variable provides a default for <code class="env">exec_prefix</code> and |
| other variables used when installing bash. |
| </p> |
| <p>You can specify separate installation prefixes for |
| architecture-specific files and architecture-independent files. |
| If you give <code class="code">configure</code> the option |
| <samp class="option">--exec-prefix=<var class="var">PATH</var></samp>, ‘<samp class="samp">make install</samp>’ will use |
| <var class="var">PATH</var> as the prefix for installing programs and libraries. |
| Documentation and other data files will still use the regular prefix. |
| </p> |
| <p>If you would like to change the installation locations for a single run, |
| you can specify these variables as arguments to <code class="code">make</code>: |
| ‘<samp class="samp">make install exec_prefix=/</samp>’ will install <code class="code">bash</code> and |
| <code class="code">bashbug</code> into <samp class="file">/bin</samp> instead of the default <samp class="file">/usr/local/bin</samp>. |
| </p> |
| <p>If you want to see the files bash will install and where it will install |
| them without changing anything on your system, specify the variable |
| <code class="env">DESTDIR</code> as an argument to <code class="code">make</code>. Its value should be the |
| absolute directory path you’d like to use as the root of your sample |
| installation tree. For example, |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">mkdir /fs1/bash-install |
| make install DESTDIR=/fs1/bash-install |
| </pre></div> |
| |
| <p>will install <code class="code">bash</code> into <samp class="file">/fs1/bash-install/usr/local/bin/bash</samp>, |
| the documentation into directories within |
| <samp class="file">/fs1/bash-install/usr/local/share</samp>, the example loadable builtins into |
| <samp class="file">/fs1/bash-install/usr/local/lib/bash</samp>, and so on. |
| You can use the usual <code class="env">exec_prefix</code> and <code class="env">prefix</code> variables to alter |
| the directory paths beneath the value of <code class="env">DESTDIR</code>. |
| </p> |
| <p>The GNU Makefile standards provide a more complete description of these |
| variables and their effects. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Specifying-the-System-Type"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Sharing-Defaults" accesskey="n" rel="next">Sharing Defaults</a>, Previous: <a href="#Installation-Names" accesskey="p" rel="prev">Installation Names</a>, Up: <a href="#Installing-Bash" accesskey="u" rel="up">Installing Bash</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Specifying-the-System-Type-1"><span>10.5 Specifying the System Type<a class="copiable-link" href="#Specifying-the-System-Type-1"> ¶</a></span></h3> |
| |
| <p>There may be some features <code class="code">configure</code> can not figure out |
| automatically, but needs to determine by the type of host Bash |
| will run on. Usually <code class="code">configure</code> can figure that |
| out, but if it prints a message saying it can not guess the host |
| type, give it the <samp class="option">--host=TYPE</samp> option. ‘<samp class="samp">TYPE</samp>’ can |
| either be a short name for the system type, such as ‘<samp class="samp">sun4</samp>’, |
| or a canonical name with three fields: ‘<samp class="samp">CPU-COMPANY-SYSTEM</samp>’ |
| (e.g., ‘<samp class="samp">i386-unknown-freebsd4.2</samp>’). |
| </p> |
| <p>See the file <samp class="file">support/config.sub</samp> for the possible |
| values of each field. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Sharing-Defaults"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Operation-Controls" accesskey="n" rel="next">Operation Controls</a>, Previous: <a href="#Specifying-the-System-Type" accesskey="p" rel="prev">Specifying the System Type</a>, Up: <a href="#Installing-Bash" accesskey="u" rel="up">Installing Bash</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Sharing-Defaults-1"><span>10.6 Sharing Defaults<a class="copiable-link" href="#Sharing-Defaults-1"> ¶</a></span></h3> |
| |
| <p>If you want to set default values for <code class="code">configure</code> scripts to |
| share, you can create a site shell script called |
| <code class="code">config.site</code> that gives default values for variables like |
| <code class="code">CC</code>, <code class="code">cache_file</code>, and <code class="code">prefix</code>. <code class="code">configure</code> |
| looks for <samp class="file">PREFIX/share/config.site</samp> if it exists, then |
| <samp class="file">PREFIX/etc/config.site</samp> if it exists. Or, you can set the |
| <code class="code">CONFIG_SITE</code> environment variable to the location of the site |
| script. A warning: the Bash <code class="code">configure</code> looks for a site script, |
| but not all <code class="code">configure</code> scripts do. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Operation-Controls"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Optional-Features" accesskey="n" rel="next">Optional Features</a>, Previous: <a href="#Sharing-Defaults" accesskey="p" rel="prev">Sharing Defaults</a>, Up: <a href="#Installing-Bash" accesskey="u" rel="up">Installing Bash</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Operation-Controls-1"><span>10.7 Operation Controls<a class="copiable-link" href="#Operation-Controls-1"> ¶</a></span></h3> |
| |
| <p><code class="code">configure</code> recognizes the following options to control how it |
| operates. |
| </p> |
| <dl class="table"> |
| <dt><code class="code">--cache-file=<var class="var">file</var></code></dt> |
| <dd><p>Use and save the results of the tests in |
| <var class="var">file</var> instead of <samp class="file">./config.cache</samp>. Set <var class="var">file</var> to |
| <samp class="file">/dev/null</samp> to disable caching, for debugging |
| <code class="code">configure</code>. |
| </p> |
| </dd> |
| <dt><code class="code">--help</code></dt> |
| <dd><p>Print a summary of the options to <code class="code">configure</code>, and exit. |
| </p> |
| </dd> |
| <dt><code class="code">--quiet</code></dt> |
| <dt><code class="code">--silent</code></dt> |
| <dt><code class="code">-q</code></dt> |
| <dd><p>Do not print messages saying which checks are being made. |
| </p> |
| </dd> |
| <dt><code class="code">--srcdir=<var class="var">dir</var></code></dt> |
| <dd><p>Look for the Bash source code in directory <var class="var">dir</var>. Usually |
| <code class="code">configure</code> can determine that directory automatically. |
| </p> |
| </dd> |
| <dt><code class="code">--version</code></dt> |
| <dd><p>Print the version of Autoconf used to generate the <code class="code">configure</code> |
| script, and exit. |
| </p></dd> |
| </dl> |
| |
| <p><code class="code">configure</code> also accepts some other, not widely used, boilerplate |
| options. ‘<samp class="samp">configure --help</samp>’ prints the complete list. |
| </p> |
| <hr> |
| </div> |
| <div class="section-level-extent" id="Optional-Features"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Operation-Controls" accesskey="p" rel="prev">Operation Controls</a>, Up: <a href="#Installing-Bash" accesskey="u" rel="up">Installing Bash</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="section" id="Optional-Features-1"><span>10.8 Optional Features<a class="copiable-link" href="#Optional-Features-1"> ¶</a></span></h3> |
| |
| <p>The Bash <code class="code">configure</code> has a number of <samp class="option">--enable-<var class="var">feature</var></samp> |
| options, where <var class="var">feature</var> indicates an optional part of Bash. |
| There are also several <samp class="option">--with-<var class="var">package</var></samp> options, |
| where <var class="var">package</var> is something like ‘<samp class="samp">bash-malloc</samp>’ or ‘<samp class="samp">purify</samp>’. |
| To turn off the default use of a package, use |
| <samp class="option">--without-<var class="var">package</var></samp>. To configure Bash without a feature |
| that is enabled by default, use <samp class="option">--disable-<var class="var">feature</var></samp>. |
| </p> |
| <p>Here is a complete list of the <samp class="option">--enable-</samp> and |
| <samp class="option">--with-</samp> options that the Bash <code class="code">configure</code> recognizes. |
| </p> |
| <dl class="table"> |
| <dt><code class="code">--with-afs</code></dt> |
| <dd><p>Define if you are using the Andrew File System from Transarc. |
| </p> |
| </dd> |
| <dt><code class="code">--with-bash-malloc</code></dt> |
| <dd><p>Use the Bash version of |
| <code class="code">malloc</code> in the directory <samp class="file">lib/malloc</samp>. This is not the same |
| <code class="code">malloc</code> that appears in <small class="sc">GNU</small> libc, but an older version |
| originally derived from the 4.2 <small class="sc">BSD</small> <code class="code">malloc</code>. This <code class="code">malloc</code> |
| is very fast, but wastes some space on each allocation. |
| This option is enabled by default. |
| The <samp class="file">NOTES</samp> file contains a list of systems for |
| which this should be turned off, and <code class="code">configure</code> disables this |
| option automatically for a number of systems. |
| </p> |
| </dd> |
| <dt><code class="code">--with-curses</code></dt> |
| <dd><p>Use the curses library instead of the termcap library. This should |
| be supplied if your system has an inadequate or incomplete termcap |
| database. |
| </p> |
| </dd> |
| <dt><code class="code">--with-gnu-malloc</code></dt> |
| <dd><p>A synonym for <code class="code">--with-bash-malloc</code>. |
| </p> |
| </dd> |
| <dt><code class="code">--with-installed-readline[=<var class="var">PREFIX</var>]</code></dt> |
| <dd><p>Define this to make Bash link with a locally-installed version of Readline |
| rather than the version in <samp class="file">lib/readline</samp>. This works only with |
| Readline 5.0 and later versions. If <var class="var">PREFIX</var> is <code class="code">yes</code> or not |
| supplied, <code class="code">configure</code> uses the values of the make variables |
| <code class="code">includedir</code> and <code class="code">libdir</code>, which are subdirectories of <code class="code">prefix</code> |
| by default, to find the installed version of Readline if it is not in |
| the standard system include and library directories. |
| If <var class="var">PREFIX</var> is <code class="code">no</code>, Bash links with the version in |
| <samp class="file">lib/readline</samp>. |
| If <var class="var">PREFIX</var> is set to any other value, <code class="code">configure</code> treats it as |
| a directory pathname and looks for |
| the installed version of Readline in subdirectories of that directory |
| (include files in <var class="var">PREFIX</var>/<code class="code">include</code> and the library in |
| <var class="var">PREFIX</var>/<code class="code">lib</code>). |
| </p> |
| </dd> |
| <dt><code class="code">--with-libintl-prefix[=<var class="var">PREFIX</var>]</code></dt> |
| <dd><p>Define this to make Bash link with a locally-installed version of the |
| libintl library instead of the version in <samp class="file">lib/intl</samp>. |
| </p> |
| </dd> |
| <dt><code class="code">--with-libiconv-prefix[=<var class="var">PREFIX</var>]</code></dt> |
| <dd><p>Define this to make Bash look for libiconv in <var class="var">PREFIX</var> instead of the |
| standard system locations. There is no version included with Bash. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-minimal-config</code></dt> |
| <dd><p>This produces a shell with minimal features, close to the historical |
| Bourne shell. |
| </p></dd> |
| </dl> |
| |
| <p>There are several <samp class="option">--enable-</samp> options that alter how Bash is |
| compiled, linked, and installed, rather than changing run-time features. |
| </p> |
| <dl class="table"> |
| <dt><code class="code">--enable-largefile</code></dt> |
| <dd><p>Enable support for <a class="uref" href="http://www.unix.org/version2/whatsnew/lfs20mar.html">large files</a> if the operating system requires special compiler options |
| to build programs which can access large files. This is enabled by |
| default, if the operating system provides large file support. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-profiling</code></dt> |
| <dd><p>This builds a Bash binary that produces profiling information to be |
| processed by <code class="code">gprof</code> each time it is executed. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-separate-helpfiles</code></dt> |
| <dd><p>Use external files for the documentation displayed by the <code class="code">help</code> builtin |
| instead of storing the text internally. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-static-link</code></dt> |
| <dd><p>This causes Bash to be linked statically, if <code class="code">gcc</code> is being used. |
| This could be used to build a version to use as root’s shell. |
| </p> |
| </dd> |
| </dl> |
| |
| <p>The ‘<samp class="samp">minimal-config</samp>’ option can be used to disable all of |
| the following options, but it is processed first, so individual |
| options may be enabled using ‘<samp class="samp">enable-<var class="var">feature</var></samp>’. |
| </p> |
| <p>All of the following options except for |
| ‘<samp class="samp">alt-array-implementation</samp>’, |
| ‘<samp class="samp">disabled-builtins</samp>’, |
| ‘<samp class="samp">direxpand-default</samp>’, |
| ‘<samp class="samp">strict-posix-default</samp>’, |
| and |
| ‘<samp class="samp">xpg-echo-default</samp>’ are |
| enabled by default, unless the operating system does not provide the |
| necessary support. |
| </p> |
| <dl class="table"> |
| <dt><code class="code">--enable-alias</code></dt> |
| <dd><p>Allow alias expansion and include the <code class="code">alias</code> and <code class="code">unalias</code> |
| builtins (see <a class="pxref" href="#Aliases">Aliases</a>). |
| </p> |
| </dd> |
| <dt><code class="code">--enable-alt-array-implementation</code></dt> |
| <dd><p>This builds bash using an alternate implementation of arrays |
| (see <a class="pxref" href="#Arrays">Arrays</a>) that provides faster access at the expense of using |
| more memory (sometimes many times more, depending on how sparse an array is). |
| </p> |
| </dd> |
| <dt><code class="code">--enable-arith-for-command</code></dt> |
| <dd><p>Include support for the alternate form of the <code class="code">for</code> command |
| that behaves like the C language <code class="code">for</code> statement |
| (see <a class="pxref" href="#Looping-Constructs">Looping Constructs</a>). |
| </p> |
| </dd> |
| <dt><code class="code">--enable-array-variables</code></dt> |
| <dd><p>Include support for one-dimensional array shell variables |
| (see <a class="pxref" href="#Arrays">Arrays</a>). |
| </p> |
| </dd> |
| <dt><code class="code">--enable-bang-history</code></dt> |
| <dd><p>Include support for <code class="code">csh</code>-like history substitution |
| (see <a class="pxref" href="#History-Interaction">History Expansion</a>). |
| </p> |
| </dd> |
| <dt><code class="code">--enable-brace-expansion</code></dt> |
| <dd><p>Include <code class="code">csh</code>-like brace expansion |
| ( <code class="code">b{a,b}c</code> → <code class="code">bac bbc</code> ). |
| See <a class="ref" href="#Brace-Expansion">Brace Expansion</a>, for a complete description. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-casemod-attributes</code></dt> |
| <dd><p>Include support for case-modifying attributes in the <code class="code">declare</code> builtin |
| and assignment statements. Variables with the <code class="code">uppercase</code> attribute, |
| for example, will have their values converted to uppercase upon assignment. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-casemod-expansion</code></dt> |
| <dd><p>Include support for case-modifying word expansions. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-command-timing</code></dt> |
| <dd><p>Include support for recognizing <code class="code">time</code> as a reserved word and for |
| displaying timing statistics for the pipeline following <code class="code">time</code> |
| (see <a class="pxref" href="#Pipelines">Pipelines</a>). |
| This allows pipelines as well as shell builtins and functions to be timed. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-cond-command</code></dt> |
| <dd><p>Include support for the <code class="code">[[</code> conditional command. |
| (see <a class="pxref" href="#Conditional-Constructs">Conditional Constructs</a>). |
| </p> |
| </dd> |
| <dt><code class="code">--enable-cond-regexp</code></dt> |
| <dd><p>Include support for matching <small class="sc">POSIX</small> regular expressions using the |
| ‘<samp class="samp">=~</samp>’ binary operator in the <code class="code">[[</code> conditional command. |
| (see <a class="pxref" href="#Conditional-Constructs">Conditional Constructs</a>). |
| </p> |
| </dd> |
| <dt><code class="code">--enable-coprocesses</code></dt> |
| <dd><p>Include support for coprocesses and the <code class="code">coproc</code> reserved word |
| (see <a class="pxref" href="#Pipelines">Pipelines</a>). |
| </p> |
| </dd> |
| <dt><code class="code">--enable-debugger</code></dt> |
| <dd><p>Include support for the bash debugger (distributed separately). |
| </p> |
| </dd> |
| <dt><code class="code">--enable-dev-fd-stat-broken</code></dt> |
| <dd><p>If calling <code class="code">stat</code> on /dev/fd/<var class="var">N</var> returns different results than |
| calling <code class="code">fstat</code> on file descriptor <var class="var">N</var>, supply this option to |
| enable a workaround. |
| This has implications for conditional commands that test file attributes. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-direxpand-default</code></dt> |
| <dd><p>Cause the <code class="code">direxpand</code> shell option (see <a class="pxref" href="#The-Shopt-Builtin">The Shopt Builtin</a>) |
| to be enabled by default when the shell starts. |
| It is normally disabled by default. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-directory-stack</code></dt> |
| <dd><p>Include support for a <code class="code">csh</code>-like directory stack and the |
| <code class="code">pushd</code>, <code class="code">popd</code>, and <code class="code">dirs</code> builtins |
| (see <a class="pxref" href="#The-Directory-Stack">The Directory Stack</a>). |
| </p> |
| </dd> |
| <dt><code class="code">--enable-disabled-builtins</code></dt> |
| <dd><p>Allow builtin commands to be invoked via ‘<samp class="samp">builtin xxx</samp>’ |
| even after <code class="code">xxx</code> has been disabled using ‘<samp class="samp">enable -n xxx</samp>’. |
| See <a class="ref" href="#Bash-Builtins">Bash Builtin Commands</a>, for details of the <code class="code">builtin</code> and |
| <code class="code">enable</code> builtin commands. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-dparen-arithmetic</code></dt> |
| <dd><p>Include support for the <code class="code">((…))</code> command |
| (see <a class="pxref" href="#Conditional-Constructs">Conditional Constructs</a>). |
| </p> |
| </dd> |
| <dt><code class="code">--enable-extended-glob</code></dt> |
| <dd><p>Include support for the extended pattern matching features described |
| above under <a class="ref" href="#Pattern-Matching">Pattern Matching</a>. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-extended-glob-default</code></dt> |
| <dd><p>Set the default value of the <code class="code">extglob</code> shell option described |
| above under <a class="ref" href="#The-Shopt-Builtin">The Shopt Builtin</a> to be enabled. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-function-import</code></dt> |
| <dd><p>Include support for importing function definitions exported by another |
| instance of the shell from the environment. This option is enabled by |
| default. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-glob-asciirange-default</code></dt> |
| <dd><p>Set the default value of the <code class="code">globasciiranges</code> shell option described |
| above under <a class="ref" href="#The-Shopt-Builtin">The Shopt Builtin</a> to be enabled. |
| This controls the behavior of character ranges when used in pattern matching |
| bracket expressions. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-help-builtin</code></dt> |
| <dd><p>Include the <code class="code">help</code> builtin, which displays help on shell builtins and |
| variables (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>). |
| </p> |
| </dd> |
| <dt><code class="code">--enable-history</code></dt> |
| <dd><p>Include command history and the <code class="code">fc</code> and <code class="code">history</code> |
| builtin commands (see <a class="pxref" href="#Bash-History-Facilities">Bash History Facilities</a>). |
| </p> |
| </dd> |
| <dt><code class="code">--enable-job-control</code></dt> |
| <dd><p>This enables the job control features (see <a class="pxref" href="#Job-Control">Job Control</a>), |
| if the operating system supports them. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-multibyte</code></dt> |
| <dd><p>This enables support for multibyte characters if the operating |
| system provides the necessary support. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-net-redirections</code></dt> |
| <dd><p>This enables the special handling of filenames of the form |
| <code class="code">/dev/tcp/<var class="var">host</var>/<var class="var">port</var></code> and |
| <code class="code">/dev/udp/<var class="var">host</var>/<var class="var">port</var></code> |
| when used in redirections (see <a class="pxref" href="#Redirections">Redirections</a>). |
| </p> |
| </dd> |
| <dt><code class="code">--enable-process-substitution</code></dt> |
| <dd><p>This enables process substitution (see <a class="pxref" href="#Process-Substitution">Process Substitution</a>) if |
| the operating system provides the necessary support. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-progcomp</code></dt> |
| <dd><p>Enable the programmable completion facilities |
| (see <a class="pxref" href="#Programmable-Completion">Programmable Completion</a>). |
| If Readline is not enabled, this option has no effect. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-prompt-string-decoding</code></dt> |
| <dd><p>Turn on the interpretation of a number of backslash-escaped characters |
| in the <code class="env">$PS0</code>, <code class="env">$PS1</code>, <code class="env">$PS2</code>, and <code class="env">$PS4</code> prompt |
| strings. See <a class="ref" href="#Controlling-the-Prompt">Controlling the Prompt</a>, for a complete list of prompt |
| string escape sequences. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-readline</code></dt> |
| <dd><p>Include support for command-line editing and history with the Bash |
| version of the Readline library (see <a class="pxref" href="#Command-Line-Editing">Command Line Editing</a>). |
| </p> |
| </dd> |
| <dt><code class="code">--enable-restricted</code></dt> |
| <dd><p>Include support for a <em class="dfn">restricted shell</em>. If this is enabled, Bash, |
| when called as <code class="code">rbash</code>, enters a restricted mode. See |
| <a class="ref" href="#The-Restricted-Shell">The Restricted Shell</a>, for a description of restricted mode. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-select</code></dt> |
| <dd><p>Include the <code class="code">select</code> compound command, which allows the generation of |
| simple menus (see <a class="pxref" href="#Conditional-Constructs">Conditional Constructs</a>). |
| </p> |
| </dd> |
| <dt><code class="code">--enable-single-help-strings</code></dt> |
| <dd><p>Store the text displayed by the <code class="code">help</code> builtin as a single string for |
| each help topic. This aids in translating the text to different languages. |
| You may need to disable this if your compiler cannot handle very long string |
| literals. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-strict-posix-default</code></dt> |
| <dd><p>Make Bash <small class="sc">POSIX</small>-conformant by default (see <a class="pxref" href="#Bash-POSIX-Mode">Bash POSIX Mode</a>). |
| </p> |
| </dd> |
| <dt><code class="code">--enable-translatable-strings</code></dt> |
| <dd><p>Enable support for <code class="code">$"<var class="var">string</var>"</code> translatable strings |
| (see <a class="pxref" href="#Locale-Translation">Locale-Specific Translation</a>). |
| </p> |
| </dd> |
| <dt><code class="code">--enable-usg-echo-default</code></dt> |
| <dd><p>A synonym for <code class="code">--enable-xpg-echo-default</code>. |
| </p> |
| </dd> |
| <dt><code class="code">--enable-xpg-echo-default</code></dt> |
| <dd><p>Make the <code class="code">echo</code> builtin expand backslash-escaped characters by default, |
| without requiring the <samp class="option">-e</samp> option. |
| This sets the default value of the <code class="code">xpg_echo</code> shell option to <code class="code">on</code>, |
| which makes the Bash <code class="code">echo</code> behave more like the version specified in |
| the Single Unix Specification, version 3. |
| See <a class="xref" href="#Bash-Builtins">Bash Builtin Commands</a>, for a description of the escape sequences that |
| <code class="code">echo</code> recognizes. |
| </p></dd> |
| </dl> |
| |
| <p>The file <samp class="file">config-top.h</samp> contains C Preprocessor |
| ‘<samp class="samp">#define</samp>’ statements for options which are not settable from |
| <code class="code">configure</code>. |
| Some of these are not meant to be changed; beware of the consequences if |
| you do. |
| Read the comments associated with each definition for more |
| information about its effect. |
| </p> |
| <hr> |
| </div> |
| </div> |
| <div class="appendix-level-extent" id="Reporting-Bugs"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Major-Differences-From-The-Bourne-Shell" accesskey="n" rel="next">Major Differences From The Bourne Shell</a>, Previous: <a href="#Installing-Bash" accesskey="p" rel="prev">Installing Bash</a>, Up: <a href="#Top" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h2 class="appendix" id="Reporting-Bugs-1"><span>Appendix A Reporting Bugs<a class="copiable-link" href="#Reporting-Bugs-1"> ¶</a></span></h2> |
| |
| <p>Please report all bugs you find in Bash. |
| But first, you should |
| make sure that it really is a bug, and that it appears in the latest |
| version of Bash. |
| The latest version of Bash is always available for FTP from |
| <a class="uref" href="ftp://ftp.gnu.org/pub/gnu/bash/">ftp://ftp.gnu.org/pub/gnu/bash/</a> and from |
| <a class="uref" href="http://git.savannah.gnu.org/cgit/bash.git/snapshot/bash-master.tar.gz">http://git.savannah.gnu.org/cgit/bash.git/snapshot/bash-master.tar.gz</a>. |
| </p> |
| <p>Once you have determined that a bug actually exists, use the |
| <code class="code">bashbug</code> command to submit a bug report. |
| If you have a fix, you are encouraged to mail that as well! |
| Suggestions and ‘philosophical’ bug reports may be mailed |
| to <a class="email" href="mailto:bug-bash@gnu.org">bug-bash@gnu.org</a> or posted to the Usenet |
| newsgroup <code class="code">gnu.bash.bug</code>. |
| </p> |
| <p>All bug reports should include: |
| </p><ul class="itemize mark-bullet"> |
| <li>The version number of Bash. |
| </li><li>The hardware and operating system. |
| </li><li>The compiler used to compile Bash. |
| </li><li>A description of the bug behaviour. |
| </li><li>A short script or ‘recipe’ which exercises the bug and may be used |
| to reproduce it. |
| </li></ul> |
| |
| <p><code class="code">bashbug</code> inserts the first three items automatically into |
| the template it provides for filing a bug report. |
| </p> |
| <p>Please send all reports concerning this manual to |
| <a class="email" href="mailto:bug-bash@gnu.org">bug-bash@gnu.org</a>. |
| </p> |
| <hr> |
| </div> |
| <div class="appendix-level-extent" id="Major-Differences-From-The-Bourne-Shell"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#GNU-Free-Documentation-License" accesskey="n" rel="next">GNU Free Documentation License</a>, Previous: <a href="#Reporting-Bugs" accesskey="p" rel="prev">Reporting Bugs</a>, Up: <a href="#Top" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h2 class="appendix" id="Major-Differences-From-The-Bourne-Shell-1"><span>Appendix B Major Differences From The Bourne Shell<a class="copiable-link" href="#Major-Differences-From-The-Bourne-Shell-1"> ¶</a></span></h2> |
| |
| <p>Bash implements essentially the same grammar, parameter and |
| variable expansion, redirection, and quoting as the Bourne Shell. |
| Bash uses the <small class="sc">POSIX</small> standard as the specification of |
| how these features are to be implemented. There are some |
| differences between the traditional Bourne shell and Bash; this |
| section quickly details the differences of significance. A |
| number of these differences are explained in greater depth in |
| previous sections. |
| This section uses the version of <code class="code">sh</code> included in SVR4.2 (the |
| last version of the historical Bourne shell) as the baseline reference. |
| </p> |
| <ul class="itemize mark-bullet"> |
| <li>Bash is <small class="sc">POSIX</small>-conformant, even where the <small class="sc">POSIX</small> specification |
| differs from traditional <code class="code">sh</code> behavior (see <a class="pxref" href="#Bash-POSIX-Mode">Bash POSIX Mode</a>). |
| |
| </li><li>Bash has multi-character invocation options (see <a class="pxref" href="#Invoking-Bash">Invoking Bash</a>). |
| |
| </li><li>Bash has command-line editing (see <a class="pxref" href="#Command-Line-Editing">Command Line Editing</a>) and |
| the <code class="code">bind</code> builtin. |
| |
| </li><li>Bash provides a programmable word completion mechanism |
| (see <a class="pxref" href="#Programmable-Completion">Programmable Completion</a>), and builtin commands |
| <code class="code">complete</code>, <code class="code">compgen</code>, and <code class="code">compopt</code>, to |
| manipulate it. |
| |
| </li><li>Bash has command history (see <a class="pxref" href="#Bash-History-Facilities">Bash History Facilities</a>) and the |
| <code class="code">history</code> and <code class="code">fc</code> builtins to manipulate it. |
| The Bash history list maintains timestamp information and uses the |
| value of the <code class="code">HISTTIMEFORMAT</code> variable to display it. |
| |
| </li><li>Bash implements <code class="code">csh</code>-like history expansion |
| (see <a class="pxref" href="#History-Interaction">History Expansion</a>). |
| |
| </li><li>Bash has one-dimensional array variables (see <a class="pxref" href="#Arrays">Arrays</a>), and the |
| appropriate variable expansions and assignment syntax to use them. |
| Several of the Bash builtins take options to act on arrays. |
| Bash provides a number of built-in array variables. |
| |
| </li><li>The <code class="code">$'…'</code> quoting syntax, which expands ANSI-C |
| backslash-escaped characters in the text between the single quotes, |
| is supported (see <a class="pxref" href="#ANSI_002dC-Quoting">ANSI-C Quoting</a>). |
| |
| </li><li>Bash supports the <code class="code">$"…"</code> quoting syntax to do |
| locale-specific translation of the characters between the double |
| quotes. The <samp class="option">-D</samp>, <samp class="option">--dump-strings</samp>, and <samp class="option">--dump-po-strings</samp> |
| invocation options list the translatable strings found in a script |
| (see <a class="pxref" href="#Locale-Translation">Locale-Specific Translation</a>). |
| |
| </li><li>Bash implements the <code class="code">!</code> keyword to negate the return value of |
| a pipeline (see <a class="pxref" href="#Pipelines">Pipelines</a>). |
| Very useful when an <code class="code">if</code> statement needs to act only if a test fails. |
| The Bash ‘<samp class="samp">-o pipefail</samp>’ option to <code class="code">set</code> will cause a pipeline to |
| return a failure status if any command fails. |
| |
| </li><li>Bash has the <code class="code">time</code> reserved word and command timing (see <a class="pxref" href="#Pipelines">Pipelines</a>). |
| The display of the timing statistics may be controlled with the |
| <code class="env">TIMEFORMAT</code> variable. |
| |
| </li><li>Bash implements the <code class="code">for (( <var class="var">expr1</var> ; <var class="var">expr2</var> ; <var class="var">expr3</var> ))</code> |
| arithmetic for command, similar to the C language (see <a class="pxref" href="#Looping-Constructs">Looping Constructs</a>). |
| |
| </li><li>Bash includes the <code class="code">select</code> compound command, which allows the |
| generation of simple menus (see <a class="pxref" href="#Conditional-Constructs">Conditional Constructs</a>). |
| |
| </li><li>Bash includes the <code class="code">[[</code> compound command, which makes conditional |
| testing part of the shell grammar (see <a class="pxref" href="#Conditional-Constructs">Conditional Constructs</a>), including |
| optional regular expression matching. |
| |
| </li><li>Bash provides optional case-insensitive matching for the <code class="code">case</code> and |
| <code class="code">[[</code> constructs. |
| |
| </li><li>Bash includes brace expansion (see <a class="pxref" href="#Brace-Expansion">Brace Expansion</a>) and tilde |
| expansion (see <a class="pxref" href="#Tilde-Expansion">Tilde Expansion</a>). |
| |
| </li><li>Bash implements command aliases and the <code class="code">alias</code> and <code class="code">unalias</code> |
| builtins (see <a class="pxref" href="#Aliases">Aliases</a>). |
| |
| </li><li>Bash provides shell arithmetic, the <code class="code">((</code> compound command |
| (see <a class="pxref" href="#Conditional-Constructs">Conditional Constructs</a>), |
| and arithmetic expansion (see <a class="pxref" href="#Shell-Arithmetic">Shell Arithmetic</a>). |
| |
| </li><li>Variables present in the shell’s initial environment are automatically |
| exported to child processes. The Bourne shell does not normally do |
| this unless the variables are explicitly marked using the <code class="code">export</code> |
| command. |
| |
| </li><li>Bash supports the ‘<samp class="samp">+=</samp>’ assignment operator, which appends to the value |
| of the variable named on the left hand side. |
| |
| </li><li>Bash includes the <small class="sc">POSIX</small> pattern removal ‘<samp class="samp">%</samp>’, ‘<samp class="samp">#</samp>’, ‘<samp class="samp">%%</samp>’ |
| and ‘<samp class="samp">##</samp>’ expansions to remove leading or trailing substrings from |
| variable values (see <a class="pxref" href="#Shell-Parameter-Expansion">Shell Parameter Expansion</a>). |
| |
| </li><li>The expansion <code class="code">${#xx}</code>, which returns the length of <code class="code">${xx}</code>, |
| is supported (see <a class="pxref" href="#Shell-Parameter-Expansion">Shell Parameter Expansion</a>). |
| |
| </li><li>The expansion <code class="code">${var:</code><var class="var">offset</var><code class="code">[:</code><var class="var">length</var><code class="code">]}</code>, |
| which expands to the substring of <code class="code">var</code>’s value of length |
| <var class="var">length</var>, beginning at <var class="var">offset</var>, is present |
| (see <a class="pxref" href="#Shell-Parameter-Expansion">Shell Parameter Expansion</a>). |
| |
| </li><li>The expansion |
| <code class="code">${<var class="var">var</var>/[/]</code><var class="var">pattern</var><code class="code">[/</code><var class="var">replacement</var><code class="code">]}</code>, |
| which matches <var class="var">pattern</var> and replaces it with <var class="var">replacement</var> in |
| the value of <var class="var">var</var>, is available (see <a class="pxref" href="#Shell-Parameter-Expansion">Shell Parameter Expansion</a>). |
| |
| </li><li>The expansion <code class="code">${!<var class="var">prefix</var>*}</code> expansion, which expands to |
| the names of all shell variables whose names begin with <var class="var">prefix</var>, |
| is available (see <a class="pxref" href="#Shell-Parameter-Expansion">Shell Parameter Expansion</a>). |
| |
| </li><li>Bash has indirect variable expansion using <code class="code">${!word}</code> |
| (see <a class="pxref" href="#Shell-Parameter-Expansion">Shell Parameter Expansion</a>). |
| |
| </li><li>Bash can expand positional parameters beyond <code class="code">$9</code> using |
| <code class="code">${<var class="var">num</var>}</code>. |
| |
| </li><li>The <small class="sc">POSIX</small> <code class="code">$()</code> form of command substitution |
| is implemented (see <a class="pxref" href="#Command-Substitution">Command Substitution</a>), |
| and preferred to the Bourne shell’s <code class="code">``</code> (which |
| is also implemented for backwards compatibility). |
| |
| </li><li>Bash has process substitution (see <a class="pxref" href="#Process-Substitution">Process Substitution</a>). |
| |
| </li><li>Bash automatically assigns variables that provide information about the |
| current user (<code class="env">UID</code>, <code class="env">EUID</code>, and <code class="env">GROUPS</code>), the current host |
| (<code class="env">HOSTTYPE</code>, <code class="env">OSTYPE</code>, <code class="env">MACHTYPE</code>, and <code class="env">HOSTNAME</code>), |
| and the instance of Bash that is running (<code class="env">BASH</code>, |
| <code class="env">BASH_VERSION</code>, and <code class="env">BASH_VERSINFO</code>). See <a class="xref" href="#Bash-Variables">Bash Variables</a>, |
| for details. |
| |
| </li><li>The <code class="env">IFS</code> variable is used to split only the results of expansion, |
| not all words (see <a class="pxref" href="#Word-Splitting">Word Splitting</a>). |
| This closes a longstanding shell security hole. |
| |
| </li><li>The filename expansion bracket expression code uses ‘<samp class="samp">!</samp>’ and ‘<samp class="samp">^</samp>’ |
| to negate the set of characters between the brackets. |
| The Bourne shell uses only ‘<samp class="samp">!</samp>’. |
| |
| </li><li>Bash implements the full set of <small class="sc">POSIX</small> filename expansion operators, |
| including character classes, equivalence classes, and |
| collating symbols (see <a class="pxref" href="#Filename-Expansion">Filename Expansion</a>). |
| |
| </li><li>Bash implements extended pattern matching features when the <code class="code">extglob</code> |
| shell option is enabled (see <a class="pxref" href="#Pattern-Matching">Pattern Matching</a>). |
| |
| </li><li>It is possible to have a variable and a function with the same name; |
| <code class="code">sh</code> does not separate the two name spaces. |
| |
| </li><li>Bash functions are permitted to have local variables using the |
| <code class="code">local</code> builtin, and thus useful recursive functions may be written |
| (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>). |
| |
| </li><li>Variable assignments preceding commands affect only that command, even |
| builtins and functions (see <a class="pxref" href="#Environment">Environment</a>). |
| In <code class="code">sh</code>, all variable assignments |
| preceding commands are global unless the command is executed from the |
| file system. |
| |
| </li><li>Bash performs filename expansion on filenames specified as operands |
| to input and output redirection operators (see <a class="pxref" href="#Redirections">Redirections</a>). |
| |
| </li><li>Bash contains the ‘<samp class="samp"><></samp>’ redirection operator, allowing a file to be |
| opened for both reading and writing, and the ‘<samp class="samp">&></samp>’ redirection |
| operator, for directing standard output and standard error to the same |
| file (see <a class="pxref" href="#Redirections">Redirections</a>). |
| |
| </li><li>Bash includes the ‘<samp class="samp"><<<</samp>’ redirection operator, allowing a string to |
| be used as the standard input to a command. |
| |
| </li><li>Bash implements the ‘<samp class="samp">[n]<&<var class="var">word</var></samp>’ and ‘<samp class="samp">[n]>&<var class="var">word</var></samp>’ |
| redirection operators, which move one file descriptor to another. |
| |
| </li><li>Bash treats a number of filenames specially when they are |
| used in redirection operators (see <a class="pxref" href="#Redirections">Redirections</a>). |
| |
| </li><li>Bash can open network connections to arbitrary machines and services |
| with the redirection operators (see <a class="pxref" href="#Redirections">Redirections</a>). |
| |
| </li><li>The <code class="code">noclobber</code> option is available to avoid overwriting existing |
| files with output redirection (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>). |
| The ‘<samp class="samp">>|</samp>’ redirection operator may be used to override <code class="code">noclobber</code>. |
| |
| </li><li>The Bash <code class="code">cd</code> and <code class="code">pwd</code> builtins (see <a class="pxref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>) |
| each take <samp class="option">-L</samp> and <samp class="option">-P</samp> options to switch between logical and |
| physical modes. |
| |
| </li><li>Bash allows a function to override a builtin with the same name, and provides |
| access to that builtin’s functionality within the function via the |
| <code class="code">builtin</code> and <code class="code">command</code> builtins (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>). |
| |
| </li><li>The <code class="code">command</code> builtin allows selective disabling of functions |
| when command lookup is performed (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>). |
| |
| </li><li>Individual builtins may be enabled or disabled using the <code class="code">enable</code> |
| builtin (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>). |
| |
| </li><li>The Bash <code class="code">exec</code> builtin takes additional options that allow users |
| to control the contents of the environment passed to the executed |
| command, and what the zeroth argument to the command is to be |
| (see <a class="pxref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>). |
| |
| </li><li>Shell functions may be exported to children via the environment |
| using <code class="code">export -f</code> (see <a class="pxref" href="#Shell-Functions">Shell Functions</a>). |
| |
| </li><li>The Bash <code class="code">export</code>, <code class="code">readonly</code>, and <code class="code">declare</code> builtins can |
| take a <samp class="option">-f</samp> option to act on shell functions, a <samp class="option">-p</samp> option to |
| display variables with various attributes set in a format that can be |
| used as shell input, a <samp class="option">-n</samp> option to remove various variable |
| attributes, and ‘<samp class="samp">name=value</samp>’ arguments to set variable attributes |
| and values simultaneously. |
| |
| </li><li>The Bash <code class="code">hash</code> builtin allows a name to be associated with |
| an arbitrary filename, even when that filename cannot be found by |
| searching the <code class="env">$PATH</code>, using ‘<samp class="samp">hash -p</samp>’ |
| (see <a class="pxref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>). |
| |
| </li><li>Bash includes a <code class="code">help</code> builtin for quick reference to shell |
| facilities (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>). |
| |
| </li><li>The <code class="code">printf</code> builtin is available to display formatted output |
| (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>). |
| |
| </li><li>The Bash <code class="code">read</code> builtin (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>) |
| will read a line ending in ‘<samp class="samp">\</samp>’ with |
| the <samp class="option">-r</samp> option, and will use the <code class="env">REPLY</code> variable as a |
| default if no non-option arguments are supplied. |
| The Bash <code class="code">read</code> builtin |
| also accepts a prompt string with the <samp class="option">-p</samp> option and will use |
| Readline to obtain the line when given the <samp class="option">-e</samp> option. |
| The <code class="code">read</code> builtin also has additional options to control input: |
| the <samp class="option">-s</samp> option will turn off echoing of input characters as |
| they are read, the <samp class="option">-t</samp> option will allow <code class="code">read</code> to time out |
| if input does not arrive within a specified number of seconds, the |
| <samp class="option">-n</samp> option will allow reading only a specified number of |
| characters rather than a full line, and the <samp class="option">-d</samp> option will read |
| until a particular character rather than newline. |
| |
| </li><li>The <code class="code">return</code> builtin may be used to abort execution of scripts |
| executed with the <code class="code">.</code> or <code class="code">source</code> builtins |
| (see <a class="pxref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>). |
| |
| </li><li>Bash includes the <code class="code">shopt</code> builtin, for finer control of shell |
| optional capabilities (see <a class="pxref" href="#The-Shopt-Builtin">The Shopt Builtin</a>), and allows these options |
| to be set and unset at shell invocation (see <a class="pxref" href="#Invoking-Bash">Invoking Bash</a>). |
| |
| </li><li>Bash has much more optional behavior controllable with the <code class="code">set</code> |
| builtin (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>). |
| |
| </li><li>The ‘<samp class="samp">-x</samp>’ (<samp class="option">xtrace</samp>) option displays commands other than |
| simple commands when performing an execution trace |
| (see <a class="pxref" href="#The-Set-Builtin">The Set Builtin</a>). |
| |
| </li><li>The <code class="code">test</code> builtin (see <a class="pxref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>) |
| is slightly different, as it implements the <small class="sc">POSIX</small> algorithm, |
| which specifies the behavior based on the number of arguments. |
| |
| </li><li>Bash includes the <code class="code">caller</code> builtin, which displays the context of |
| any active subroutine call (a shell function or a script executed with |
| the <code class="code">.</code> or <code class="code">source</code> builtins). This supports the Bash |
| debugger. |
| |
| </li><li>The <code class="code">trap</code> builtin (see <a class="pxref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>) allows a |
| <code class="code">DEBUG</code> pseudo-signal specification, similar to <code class="code">EXIT</code>. |
| Commands specified with a <code class="code">DEBUG</code> trap are executed before every |
| simple command, <code class="code">for</code> command, <code class="code">case</code> command, |
| <code class="code">select</code> command, every arithmetic <code class="code">for</code> command, and before |
| the first command executes in a shell function. |
| The <code class="code">DEBUG</code> trap is not inherited by shell functions unless the |
| function has been given the <code class="code">trace</code> attribute or the |
| <code class="code">functrace</code> option has been enabled using the <code class="code">shopt</code> builtin. |
| The <code class="code">extdebug</code> shell option has additional effects on the |
| <code class="code">DEBUG</code> trap. |
| |
| <p>The <code class="code">trap</code> builtin (see <a class="pxref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>) allows an |
| <code class="code">ERR</code> pseudo-signal specification, similar to <code class="code">EXIT</code> and <code class="code">DEBUG</code>. |
| Commands specified with an <code class="code">ERR</code> trap are executed after a simple |
| command fails, with a few exceptions. |
| The <code class="code">ERR</code> trap is not inherited by shell functions unless the |
| <code class="code">-o errtrace</code> option to the <code class="code">set</code> builtin is enabled. |
| </p> |
| <p>The <code class="code">trap</code> builtin (see <a class="pxref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>) allows a |
| <code class="code">RETURN</code> pseudo-signal specification, similar to |
| <code class="code">EXIT</code> and <code class="code">DEBUG</code>. |
| Commands specified with a <code class="code">RETURN</code> trap are executed before |
| execution resumes after a shell function or a shell script executed with |
| <code class="code">.</code> or <code class="code">source</code> returns. |
| The <code class="code">RETURN</code> trap is not inherited by shell functions unless the |
| function has been given the <code class="code">trace</code> attribute or the |
| <code class="code">functrace</code> option has been enabled using the <code class="code">shopt</code> builtin. |
| </p> |
| </li><li>The Bash <code class="code">type</code> builtin is more extensive and gives more information |
| about the names it finds (see <a class="pxref" href="#Bash-Builtins">Bash Builtin Commands</a>). |
| |
| </li><li>The Bash <code class="code">umask</code> builtin permits a <samp class="option">-p</samp> option to cause |
| the output to be displayed in the form of a <code class="code">umask</code> command |
| that may be reused as input (see <a class="pxref" href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a>). |
| |
| </li><li>Bash implements a <code class="code">csh</code>-like directory stack, and provides the |
| <code class="code">pushd</code>, <code class="code">popd</code>, and <code class="code">dirs</code> builtins to manipulate it |
| (see <a class="pxref" href="#The-Directory-Stack">The Directory Stack</a>). |
| Bash also makes the directory stack visible as the value of the |
| <code class="env">DIRSTACK</code> shell variable. |
| |
| </li><li>Bash interprets special backslash-escaped characters in the prompt |
| strings when interactive (see <a class="pxref" href="#Controlling-the-Prompt">Controlling the Prompt</a>). |
| |
| </li><li>The Bash restricted mode is more useful (see <a class="pxref" href="#The-Restricted-Shell">The Restricted Shell</a>); |
| the SVR4.2 shell restricted mode is too limited. |
| |
| </li><li>The <code class="code">disown</code> builtin can remove a job from the internal shell |
| job table (see <a class="pxref" href="#Job-Control-Builtins">Job Control Builtins</a>) or suppress the sending |
| of <code class="code">SIGHUP</code> to a job when the shell exits as the result of a |
| <code class="code">SIGHUP</code>. |
| |
| </li><li>Bash includes a number of features to support a separate debugger for |
| shell scripts. |
| |
| </li><li>The SVR4.2 shell has two privilege-related builtins |
| (<code class="code">mldmode</code> and <code class="code">priv</code>) not present in Bash. |
| |
| </li><li>Bash does not have the <code class="code">stop</code> or <code class="code">newgrp</code> builtins. |
| |
| </li><li>Bash does not use the <code class="env">SHACCT</code> variable or perform shell accounting. |
| |
| </li><li>The SVR4.2 <code class="code">sh</code> uses a <code class="env">TIMEOUT</code> variable like Bash uses |
| <code class="env">TMOUT</code>. |
| |
| </li></ul> |
| |
| <p>More features unique to Bash may be found in <a class="ref" href="#Bash-Features">Bash Features</a>. |
| </p> |
| |
| <ul class="mini-toc"> |
| <li><a href="#Implementation-Differences-From-The-SVR4_002e2-Shell" accesskey="1">Implementation Differences From The SVR4.2 Shell</a></li> |
| </ul> |
| <div class="appendixsec-level-extent" id="Implementation-Differences-From-The-SVR4_002e2-Shell"> |
| <h3 class="appendixsec"><span>B.1 Implementation Differences From The SVR4.2 Shell<a class="copiable-link" href="#Implementation-Differences-From-The-SVR4_002e2-Shell"> ¶</a></span></h3> |
| |
| <p>Since Bash is a completely new implementation, it does not suffer from |
| many of the limitations of the SVR4.2 shell. For instance: |
| </p> |
| <ul class="itemize mark-bullet"> |
| <li>Bash does not fork a subshell when redirecting into or out of |
| a shell control structure such as an <code class="code">if</code> or <code class="code">while</code> |
| statement. |
| |
| </li><li>Bash does not allow unbalanced quotes. The SVR4.2 shell will silently |
| insert a needed closing quote at <code class="code">EOF</code> under certain circumstances. |
| This can be the cause of some hard-to-find errors. |
| |
| </li><li>The SVR4.2 shell uses a baroque memory management scheme based on |
| trapping <code class="code">SIGSEGV</code>. If the shell is started from a process with |
| <code class="code">SIGSEGV</code> blocked (e.g., by using the <code class="code">system()</code> C library |
| function call), it misbehaves badly. |
| |
| </li><li>In a questionable attempt at security, the SVR4.2 shell, |
| when invoked without the <samp class="option">-p</samp> option, will alter its real |
| and effective <small class="sc">UID</small> and <small class="sc">GID</small> if they are less than some |
| magic threshold value, commonly 100. |
| This can lead to unexpected results. |
| |
| </li><li>The SVR4.2 shell does not allow users to trap <code class="code">SIGSEGV</code>, |
| <code class="code">SIGALRM</code>, or <code class="code">SIGCHLD</code>. |
| |
| </li><li>The SVR4.2 shell does not allow the <code class="env">IFS</code>, <code class="env">MAILCHECK</code>, |
| <code class="env">PATH</code>, <code class="env">PS1</code>, or <code class="env">PS2</code> variables to be unset. |
| |
| </li><li>The SVR4.2 shell treats ‘<samp class="samp">^</samp>’ as the undocumented equivalent of |
| ‘<samp class="samp">|</samp>’. |
| |
| </li><li>Bash allows multiple option arguments when it is invoked (<code class="code">-x -v</code>); |
| the SVR4.2 shell allows only one option argument (<code class="code">-xv</code>). In |
| fact, some versions of the shell dump core if the second argument begins |
| with a ‘<samp class="samp">-</samp>’. |
| |
| </li><li>The SVR4.2 shell exits a script if any builtin fails; Bash exits |
| a script only if one of the <small class="sc">POSIX</small> special builtins fails, and |
| only for certain failures, as enumerated in the <small class="sc">POSIX</small> standard. |
| |
| </li><li>The SVR4.2 shell behaves differently when invoked as <code class="code">jsh</code> |
| (it turns on job control). |
| </li></ul> |
| |
| <hr> |
| </div> |
| </div> |
| <div class="appendix-level-extent" id="GNU-Free-Documentation-License"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Indexes" accesskey="n" rel="next">Indexes</a>, Previous: <a href="#Major-Differences-From-The-Bourne-Shell" accesskey="p" rel="prev">Major Differences From The Bourne Shell</a>, Up: <a href="#Top" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h2 class="appendix" id="GNU-Free-Documentation-License-1"><span>Appendix C GNU Free Documentation License<a class="copiable-link" href="#GNU-Free-Documentation-License-1"> ¶</a></span></h2> |
| |
| <div class="center">Version 1.3, 3 November 2008 |
| </div> |
| |
| <div class="display"> |
| <pre class="display-preformatted">Copyright © 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc. |
| <a class="uref" href="http://fsf.org/">http://fsf.org/</a> |
| |
| Everyone is permitted to copy and distribute verbatim copies |
| of this license document, but changing it is not allowed. |
| </pre></div> |
| |
| <ol class="enumerate" start="0"> |
| <li> PREAMBLE |
| |
| <p>The purpose of this License is to make a manual, textbook, or other |
| functional and useful document <em class="dfn">free</em> in the sense of freedom: to |
| assure everyone the effective freedom to copy and redistribute it, |
| with or without modifying it, either commercially or noncommercially. |
| Secondarily, this License preserves for the author and publisher a way |
| to get credit for their work, while not being considered responsible |
| for modifications made by others. |
| </p> |
| <p>This License is a kind of “copyleft”, which means that derivative |
| works of the document must themselves be free in the same sense. It |
| complements the GNU General Public License, which is a copyleft |
| license designed for free software. |
| </p> |
| <p>We have designed this License in order to use it for manuals for free |
| software, because free software needs free documentation: a free |
| program should come with manuals providing the same freedoms that the |
| software does. But this License is not limited to software manuals; |
| it can be used for any textual work, regardless of subject matter or |
| whether it is published as a printed book. We recommend this License |
| principally for works whose purpose is instruction or reference. |
| </p> |
| </li><li> APPLICABILITY AND DEFINITIONS |
| |
| <p>This License applies to any manual or other work, in any medium, that |
| contains a notice placed by the copyright holder saying it can be |
| distributed under the terms of this License. Such a notice grants a |
| world-wide, royalty-free license, unlimited in duration, to use that |
| work under the conditions stated herein. The “Document”, below, |
| refers to any such manual or work. Any member of the public is a |
| licensee, and is addressed as “you”. You accept the license if you |
| copy, modify or distribute the work in a way requiring permission |
| under copyright law. |
| </p> |
| <p>A “Modified Version” of the Document means any work containing the |
| Document or a portion of it, either copied verbatim, or with |
| modifications and/or translated into another language. |
| </p> |
| <p>A “Secondary Section” is a named appendix or a front-matter section |
| of the Document that deals exclusively with the relationship of the |
| publishers or authors of the Document to the Document’s overall |
| subject (or to related matters) and contains nothing that could fall |
| directly within that overall subject. (Thus, if the Document is in |
| part a textbook of mathematics, a Secondary Section may not explain |
| any mathematics.) The relationship could be a matter of historical |
| connection with the subject or with related matters, or of legal, |
| commercial, philosophical, ethical or political position regarding |
| them. |
| </p> |
| <p>The “Invariant Sections” are certain Secondary Sections whose titles |
| are designated, as being those of Invariant Sections, in the notice |
| that says that the Document is released under this License. If a |
| section does not fit the above definition of Secondary then it is not |
| allowed to be designated as Invariant. The Document may contain zero |
| Invariant Sections. If the Document does not identify any Invariant |
| Sections then there are none. |
| </p> |
| <p>The “Cover Texts” are certain short passages of text that are listed, |
| as Front-Cover Texts or Back-Cover Texts, in the notice that says that |
| the Document is released under this License. A Front-Cover Text may |
| be at most 5 words, and a Back-Cover Text may be at most 25 words. |
| </p> |
| <p>A “Transparent” copy of the Document means a machine-readable copy, |
| represented in a format whose specification is available to the |
| general public, that is suitable for revising the document |
| straightforwardly with generic text editors or (for images composed of |
| pixels) generic paint programs or (for drawings) some widely available |
| drawing editor, and that is suitable for input to text formatters or |
| for automatic translation to a variety of formats suitable for input |
| to text formatters. A copy made in an otherwise Transparent file |
| format whose markup, or absence of markup, has been arranged to thwart |
| or discourage subsequent modification by readers is not Transparent. |
| An image format is not Transparent if used for any substantial amount |
| of text. A copy that is not “Transparent” is called “Opaque”. |
| </p> |
| <p>Examples of suitable formats for Transparent copies include plain |
| <small class="sc">ASCII</small> without markup, Texinfo input format, LaTeX input |
| format, <abbr class="acronym">SGML</abbr> or <abbr class="acronym">XML</abbr> using a publicly available |
| <abbr class="acronym">DTD</abbr>, and standard-conforming simple <abbr class="acronym">HTML</abbr>, |
| PostScript or <abbr class="acronym">PDF</abbr> designed for human modification. Examples |
| of transparent image formats include <abbr class="acronym">PNG</abbr>, <abbr class="acronym">XCF</abbr> and |
| <abbr class="acronym">JPG</abbr>. Opaque formats include proprietary formats that can be |
| read and edited only by proprietary word processors, <abbr class="acronym">SGML</abbr> or |
| <abbr class="acronym">XML</abbr> for which the <abbr class="acronym">DTD</abbr> and/or processing tools are |
| not generally available, and the machine-generated <abbr class="acronym">HTML</abbr>, |
| PostScript or <abbr class="acronym">PDF</abbr> produced by some word processors for |
| output purposes only. |
| </p> |
| <p>The “Title Page” means, for a printed book, the title page itself, |
| plus such following pages as are needed to hold, legibly, the material |
| this License requires to appear in the title page. For works in |
| formats which do not have any title page as such, “Title Page” means |
| the text near the most prominent appearance of the work’s title, |
| preceding the beginning of the body of the text. |
| </p> |
| <p>The “publisher” means any person or entity that distributes copies |
| of the Document to the public. |
| </p> |
| <p>A section “Entitled XYZ” means a named subunit of the Document whose |
| title either is precisely XYZ or contains XYZ in parentheses following |
| text that translates XYZ in another language. (Here XYZ stands for a |
| specific section name mentioned below, such as “Acknowledgements”, |
| “Dedications”, “Endorsements”, or “History”.) To “Preserve the Title” |
| of such a section when you modify the Document means that it remains a |
| section “Entitled XYZ” according to this definition. |
| </p> |
| <p>The Document may include Warranty Disclaimers next to the notice which |
| states that this License applies to the Document. These Warranty |
| Disclaimers are considered to be included by reference in this |
| License, but only as regards disclaiming warranties: any other |
| implication that these Warranty Disclaimers may have is void and has |
| no effect on the meaning of this License. |
| </p> |
| </li><li> VERBATIM COPYING |
| |
| <p>You may copy and distribute the Document in any medium, either |
| commercially or noncommercially, provided that this License, the |
| copyright notices, and the license notice saying this License applies |
| to the Document are reproduced in all copies, and that you add no other |
| conditions whatsoever to those of this License. You may not use |
| technical measures to obstruct or control the reading or further |
| copying of the copies you make or distribute. However, you may accept |
| compensation in exchange for copies. If you distribute a large enough |
| number of copies you must also follow the conditions in section 3. |
| </p> |
| <p>You may also lend copies, under the same conditions stated above, and |
| you may publicly display copies. |
| </p> |
| </li><li> COPYING IN QUANTITY |
| |
| <p>If you publish printed copies (or copies in media that commonly have |
| printed covers) of the Document, numbering more than 100, and the |
| Document’s license notice requires Cover Texts, you must enclose the |
| copies in covers that carry, clearly and legibly, all these Cover |
| Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on |
| the back cover. Both covers must also clearly and legibly identify |
| you as the publisher of these copies. The front cover must present |
| the full title with all words of the title equally prominent and |
| visible. You may add other material on the covers in addition. |
| Copying with changes limited to the covers, as long as they preserve |
| the title of the Document and satisfy these conditions, can be treated |
| as verbatim copying in other respects. |
| </p> |
| <p>If the required texts for either cover are too voluminous to fit |
| legibly, you should put the first ones listed (as many as fit |
| reasonably) on the actual cover, and continue the rest onto adjacent |
| pages. |
| </p> |
| <p>If you publish or distribute Opaque copies of the Document numbering |
| more than 100, you must either include a machine-readable Transparent |
| copy along with each Opaque copy, or state in or with each Opaque copy |
| a computer-network location from which the general network-using |
| public has access to download using public-standard network protocols |
| a complete Transparent copy of the Document, free of added material. |
| If you use the latter option, you must take reasonably prudent steps, |
| when you begin distribution of Opaque copies in quantity, to ensure |
| that this Transparent copy will remain thus accessible at the stated |
| location until at least one year after the last time you distribute an |
| Opaque copy (directly or through your agents or retailers) of that |
| edition to the public. |
| </p> |
| <p>It is requested, but not required, that you contact the authors of the |
| Document well before redistributing any large number of copies, to give |
| them a chance to provide you with an updated version of the Document. |
| </p> |
| </li><li> MODIFICATIONS |
| |
| <p>You may copy and distribute a Modified Version of the Document under |
| the conditions of sections 2 and 3 above, provided that you release |
| the Modified Version under precisely this License, with the Modified |
| Version filling the role of the Document, thus licensing distribution |
| and modification of the Modified Version to whoever possesses a copy |
| of it. In addition, you must do these things in the Modified Version: |
| </p> |
| <ol class="enumerate" type="A" start="1"> |
| <li> Use in the Title Page (and on the covers, if any) a title distinct |
| from that of the Document, and from those of previous versions |
| (which should, if there were any, be listed in the History section |
| of the Document). You may use the same title as a previous version |
| if the original publisher of that version gives permission. |
| |
| </li><li> List on the Title Page, as authors, one or more persons or entities |
| responsible for authorship of the modifications in the Modified |
| Version, together with at least five of the principal authors of the |
| Document (all of its principal authors, if it has fewer than five), |
| unless they release you from this requirement. |
| |
| </li><li> State on the Title page the name of the publisher of the |
| Modified Version, as the publisher. |
| |
| </li><li> Preserve all the copyright notices of the Document. |
| |
| </li><li> Add an appropriate copyright notice for your modifications |
| adjacent to the other copyright notices. |
| |
| </li><li> Include, immediately after the copyright notices, a license notice |
| giving the public permission to use the Modified Version under the |
| terms of this License, in the form shown in the Addendum below. |
| |
| </li><li> Preserve in that license notice the full lists of Invariant Sections |
| and required Cover Texts given in the Document’s license notice. |
| |
| </li><li> Include an unaltered copy of this License. |
| |
| </li><li> Preserve the section Entitled “History”, Preserve its Title, and add |
| to it an item stating at least the title, year, new authors, and |
| publisher of the Modified Version as given on the Title Page. If |
| there is no section Entitled “History” in the Document, create one |
| stating the title, year, authors, and publisher of the Document as |
| given on its Title Page, then add an item describing the Modified |
| Version as stated in the previous sentence. |
| |
| </li><li> Preserve the network location, if any, given in the Document for |
| public access to a Transparent copy of the Document, and likewise |
| the network locations given in the Document for previous versions |
| it was based on. These may be placed in the “History” section. |
| You may omit a network location for a work that was published at |
| least four years before the Document itself, or if the original |
| publisher of the version it refers to gives permission. |
| |
| </li><li> For any section Entitled “Acknowledgements” or “Dedications”, Preserve |
| the Title of the section, and preserve in the section all the |
| substance and tone of each of the contributor acknowledgements and/or |
| dedications given therein. |
| |
| </li><li> Preserve all the Invariant Sections of the Document, |
| unaltered in their text and in their titles. Section numbers |
| or the equivalent are not considered part of the section titles. |
| |
| </li><li> Delete any section Entitled “Endorsements”. Such a section |
| may not be included in the Modified Version. |
| |
| </li><li> Do not retitle any existing section to be Entitled “Endorsements” or |
| to conflict in title with any Invariant Section. |
| |
| </li><li> Preserve any Warranty Disclaimers. |
| </li></ol> |
| |
| <p>If the Modified Version includes new front-matter sections or |
| appendices that qualify as Secondary Sections and contain no material |
| copied from the Document, you may at your option designate some or all |
| of these sections as invariant. To do this, add their titles to the |
| list of Invariant Sections in the Modified Version’s license notice. |
| These titles must be distinct from any other section titles. |
| </p> |
| <p>You may add a section Entitled “Endorsements”, provided it contains |
| nothing but endorsements of your Modified Version by various |
| parties—for example, statements of peer review or that the text has |
| been approved by an organization as the authoritative definition of a |
| standard. |
| </p> |
| <p>You may add a passage of up to five words as a Front-Cover Text, and a |
| passage of up to 25 words as a Back-Cover Text, to the end of the list |
| of Cover Texts in the Modified Version. Only one passage of |
| Front-Cover Text and one of Back-Cover Text may be added by (or |
| through arrangements made by) any one entity. If the Document already |
| includes a cover text for the same cover, previously added by you or |
| by arrangement made by the same entity you are acting on behalf of, |
| you may not add another; but you may replace the old one, on explicit |
| permission from the previous publisher that added the old one. |
| </p> |
| <p>The author(s) and publisher(s) of the Document do not by this License |
| give permission to use their names for publicity for or to assert or |
| imply endorsement of any Modified Version. |
| </p> |
| </li><li> COMBINING DOCUMENTS |
| |
| <p>You may combine the Document with other documents released under this |
| License, under the terms defined in section 4 above for modified |
| versions, provided that you include in the combination all of the |
| Invariant Sections of all of the original documents, unmodified, and |
| list them all as Invariant Sections of your combined work in its |
| license notice, and that you preserve all their Warranty Disclaimers. |
| </p> |
| <p>The combined work need only contain one copy of this License, and |
| multiple identical Invariant Sections may be replaced with a single |
| copy. If there are multiple Invariant Sections with the same name but |
| different contents, make the title of each such section unique by |
| adding at the end of it, in parentheses, the name of the original |
| author or publisher of that section if known, or else a unique number. |
| Make the same adjustment to the section titles in the list of |
| Invariant Sections in the license notice of the combined work. |
| </p> |
| <p>In the combination, you must combine any sections Entitled “History” |
| in the various original documents, forming one section Entitled |
| “History”; likewise combine any sections Entitled “Acknowledgements”, |
| and any sections Entitled “Dedications”. You must delete all |
| sections Entitled “Endorsements.” |
| </p> |
| </li><li> COLLECTIONS OF DOCUMENTS |
| |
| <p>You may make a collection consisting of the Document and other documents |
| released under this License, and replace the individual copies of this |
| License in the various documents with a single copy that is included in |
| the collection, provided that you follow the rules of this License for |
| verbatim copying of each of the documents in all other respects. |
| </p> |
| <p>You may extract a single document from such a collection, and distribute |
| it individually under this License, provided you insert a copy of this |
| License into the extracted document, and follow this License in all |
| other respects regarding verbatim copying of that document. |
| </p> |
| </li><li> AGGREGATION WITH INDEPENDENT WORKS |
| |
| <p>A compilation of the Document or its derivatives with other separate |
| and independent documents or works, in or on a volume of a storage or |
| distribution medium, is called an “aggregate” if the copyright |
| resulting from the compilation is not used to limit the legal rights |
| of the compilation’s users beyond what the individual works permit. |
| When the Document is included in an aggregate, this License does not |
| apply to the other works in the aggregate which are not themselves |
| derivative works of the Document. |
| </p> |
| <p>If the Cover Text requirement of section 3 is applicable to these |
| copies of the Document, then if the Document is less than one half of |
| the entire aggregate, the Document’s Cover Texts may be placed on |
| covers that bracket the Document within the aggregate, or the |
| electronic equivalent of covers if the Document is in electronic form. |
| Otherwise they must appear on printed covers that bracket the whole |
| aggregate. |
| </p> |
| </li><li> TRANSLATION |
| |
| <p>Translation is considered a kind of modification, so you may |
| distribute translations of the Document under the terms of section 4. |
| Replacing Invariant Sections with translations requires special |
| permission from their copyright holders, but you may include |
| translations of some or all Invariant Sections in addition to the |
| original versions of these Invariant Sections. You may include a |
| translation of this License, and all the license notices in the |
| Document, and any Warranty Disclaimers, provided that you also include |
| the original English version of this License and the original versions |
| of those notices and disclaimers. In case of a disagreement between |
| the translation and the original version of this License or a notice |
| or disclaimer, the original version will prevail. |
| </p> |
| <p>If a section in the Document is Entitled “Acknowledgements”, |
| “Dedications”, or “History”, the requirement (section 4) to Preserve |
| its Title (section 1) will typically require changing the actual |
| title. |
| </p> |
| </li><li> TERMINATION |
| |
| <p>You may not copy, modify, sublicense, or distribute the Document |
| except as expressly provided under this License. Any attempt |
| otherwise to copy, modify, sublicense, or distribute it is void, and |
| will automatically terminate your rights under this License. |
| </p> |
| <p>However, if you cease all violation of this License, then your license |
| from a particular copyright holder is reinstated (a) provisionally, |
| unless and until the copyright holder explicitly and finally |
| terminates your license, and (b) permanently, if the copyright holder |
| fails to notify you of the violation by some reasonable means prior to |
| 60 days after the cessation. |
| </p> |
| <p>Moreover, your license from a particular copyright holder is |
| reinstated permanently if the copyright holder notifies you of the |
| violation by some reasonable means, this is the first time you have |
| received notice of violation of this License (for any work) from that |
| copyright holder, and you cure the violation prior to 30 days after |
| your receipt of the notice. |
| </p> |
| <p>Termination of your rights under this section does not terminate the |
| licenses of parties who have received copies or rights from you under |
| this License. If your rights have been terminated and not permanently |
| reinstated, receipt of a copy of some or all of the same material does |
| not give you any rights to use it. |
| </p> |
| </li><li> FUTURE REVISIONS OF THIS LICENSE |
| |
| <p>The Free Software Foundation may publish new, revised versions |
| of the GNU Free Documentation License from time to time. Such new |
| versions will be similar in spirit to the present version, but may |
| differ in detail to address new problems or concerns. See |
| <a class="uref" href="http://www.gnu.org/copyleft/">http://www.gnu.org/copyleft/</a>. |
| </p> |
| <p>Each version of the License is given a distinguishing version number. |
| If the Document specifies that a particular numbered version of this |
| License “or any later version” applies to it, you have the option of |
| following the terms and conditions either of that specified version or |
| of any later version that has been published (not as a draft) by the |
| Free Software Foundation. If the Document does not specify a version |
| number of this License, you may choose any version ever published (not |
| as a draft) by the Free Software Foundation. If the Document |
| specifies that a proxy can decide which future versions of this |
| License can be used, that proxy’s public statement of acceptance of a |
| version permanently authorizes you to choose that version for the |
| Document. |
| </p> |
| </li><li> RELICENSING |
| |
| <p>“Massive Multiauthor Collaboration Site” (or “MMC Site”) means any |
| World Wide Web server that publishes copyrightable works and also |
| provides prominent facilities for anybody to edit those works. A |
| public wiki that anybody can edit is an example of such a server. A |
| “Massive Multiauthor Collaboration” (or “MMC”) contained in the |
| site means any set of copyrightable works thus published on the MMC |
| site. |
| </p> |
| <p>“CC-BY-SA” means the Creative Commons Attribution-Share Alike 3.0 |
| license published by Creative Commons Corporation, a not-for-profit |
| corporation with a principal place of business in San Francisco, |
| California, as well as future copyleft versions of that license |
| published by that same organization. |
| </p> |
| <p>“Incorporate” means to publish or republish a Document, in whole or |
| in part, as part of another Document. |
| </p> |
| <p>An MMC is “eligible for relicensing” if it is licensed under this |
| License, and if all works that were first published under this License |
| somewhere other than this MMC, and subsequently incorporated in whole |
| or in part into the MMC, (1) had no cover texts or invariant sections, |
| and (2) were thus incorporated prior to November 1, 2008. |
| </p> |
| <p>The operator of an MMC Site may republish an MMC contained in the site |
| under CC-BY-SA on the same site at any time before August 1, 2009, |
| provided the MMC is eligible for relicensing. |
| </p> |
| </li></ol> |
| |
| <h3 class="heading" id="ADDENDUM_003a-How-to-use-this-License-for-your-documents"><span>ADDENDUM: How to use this License for your documents<a class="copiable-link" href="#ADDENDUM_003a-How-to-use-this-License-for-your-documents"> ¶</a></span></h3> |
| |
| <p>To use this License in a document you have written, include a copy of |
| the License in the document and put the following copyright and |
| license notices just after the title page: |
| </p> |
| <div class="example smallexample"> |
| <div class="group"><pre class="example-preformatted"> Copyright (C) <var class="var">year</var> <var class="var">your name</var>. |
| Permission is granted to copy, distribute and/or modify this document |
| under the terms of the GNU Free Documentation License, Version 1.3 |
| or any later version published by the Free Software Foundation; |
| with no Invariant Sections, no Front-Cover Texts, and no Back-Cover |
| Texts. A copy of the license is included in the section entitled ``GNU |
| Free Documentation License''. |
| </pre></div></div> |
| |
| <p>If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, |
| replace the “with…Texts.” line with this: |
| </p> |
| <div class="example smallexample"> |
| <div class="group"><pre class="example-preformatted"> with the Invariant Sections being <var class="var">list their titles</var>, with |
| the Front-Cover Texts being <var class="var">list</var>, and with the Back-Cover Texts |
| being <var class="var">list</var>. |
| </pre></div></div> |
| |
| <p>If you have Invariant Sections without Cover Texts, or some other |
| combination of the three, merge those two alternatives to suit the |
| situation. |
| </p> |
| <p>If your document contains nontrivial examples of program code, we |
| recommend releasing these examples in parallel under your choice of |
| free software license, such as the GNU General Public License, |
| to permit their use in free software. |
| </p> |
| |
| |
| <hr> |
| </div> |
| <div class="appendix-level-extent" id="Indexes"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#GNU-Free-Documentation-License" accesskey="p" rel="prev">GNU Free Documentation License</a>, Up: <a href="#Top" accesskey="u" rel="up">Bash Features</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h2 class="appendix" id="Indexes-1"><span>Appendix D Indexes<a class="copiable-link" href="#Indexes-1"> ¶</a></span></h2> |
| |
| |
| <ul class="mini-toc"> |
| <li><a href="#Builtin-Index" accesskey="1">Index of Shell Builtin Commands</a></li> |
| <li><a href="#Reserved-Word-Index" accesskey="2">Index of Shell Reserved Words</a></li> |
| <li><a href="#Variable-Index" accesskey="3">Parameter and Variable Index</a></li> |
| <li><a href="#Function-Index" accesskey="4">Function Index</a></li> |
| <li><a href="#Concept-Index" accesskey="5">Concept Index</a></li> |
| </ul> |
| <hr> |
| <div class="appendixsec-level-extent" id="Builtin-Index"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Reserved-Word-Index" accesskey="n" rel="next">Index of Shell Reserved Words</a>, Up: <a href="#Indexes" accesskey="u" rel="up">Indexes</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="appendixsec" id="Index-of-Shell-Builtin-Commands"><span>D.1 Index of Shell Builtin Commands<a class="copiable-link" href="#Index-of-Shell-Builtin-Commands"> ¶</a></span></h3> |
| <div class="printindex bt-printindex"> |
| <table class="bt-letters-header-printindex"><tr><th>Jump to: </th><td><a class="summary-letter-printindex" href="#Builtin-Index_bt_symbol-1"><b>:</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_symbol-2"><b>.</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_symbol-3"><b>[</b></a> |
| |
| <br> |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-A"><b>A</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-B"><b>B</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-C"><b>C</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-D"><b>D</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-E"><b>E</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-F"><b>F</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-G"><b>G</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-H"><b>H</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-J"><b>J</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-K"><b>K</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-L"><b>L</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-M"><b>M</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-P"><b>P</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-R"><b>R</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-S"><b>S</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-T"><b>T</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-U"><b>U</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-W"><b>W</b></a> |
| |
| </td></tr></table> |
| <table class="bt-entries-printindex" border="0"> |
| <tr><td></td><th class="entries-header-printindex">Index Entry</th><th class="sections-header-printindex">Section</th></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_symbol-1">:</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_003a"><code>:</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_symbol-2">.</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_002e"><code>.</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_symbol-3">[</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_005b"><code>[</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_letter-A">A</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-alias"><code>alias</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_letter-B">B</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-bg"><code>bg</code></a></td><td class="printindex-index-section"><a href="#Job-Control-Builtins">Job Control Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-bind"><code>bind</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-break"><code>break</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-builtin"><code>builtin</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_letter-C">C</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-caller"><code>caller</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-cd"><code>cd</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-command"><code>command</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-compgen"><code>compgen</code></a></td><td class="printindex-index-section"><a href="#Programmable-Completion-Builtins">Programmable Completion Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-complete"><code>complete</code></a></td><td class="printindex-index-section"><a href="#Programmable-Completion-Builtins">Programmable Completion Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-compopt"><code>compopt</code></a></td><td class="printindex-index-section"><a href="#Programmable-Completion-Builtins">Programmable Completion Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-continue"><code>continue</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_letter-D">D</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-declare"><code>declare</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-dirs"><code>dirs</code></a></td><td class="printindex-index-section"><a href="#Directory-Stack-Builtins">Directory Stack Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-disown"><code>disown</code></a></td><td class="printindex-index-section"><a href="#Job-Control-Builtins">Job Control Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_letter-E">E</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-echo"><code>echo</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-enable"><code>enable</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-eval"><code>eval</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-exec"><code>exec</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-exit"><code>exit</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-export"><code>export</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_letter-F">F</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-fc"><code>fc</code></a></td><td class="printindex-index-section"><a href="#Bash-History-Builtins">Bash History Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-fg"><code>fg</code></a></td><td class="printindex-index-section"><a href="#Job-Control-Builtins">Job Control Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_letter-G">G</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-getopts"><code>getopts</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_letter-H">H</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-hash"><code>hash</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-help"><code>help</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-history"><code>history</code></a></td><td class="printindex-index-section"><a href="#Bash-History-Builtins">Bash History Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_letter-J">J</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-jobs"><code>jobs</code></a></td><td class="printindex-index-section"><a href="#Job-Control-Builtins">Job Control Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_letter-K">K</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-kill"><code>kill</code></a></td><td class="printindex-index-section"><a href="#Job-Control-Builtins">Job Control Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_letter-L">L</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-let"><code>let</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-local"><code>local</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-logout"><code>logout</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_letter-M">M</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-mapfile"><code>mapfile</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_letter-P">P</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-popd"><code>popd</code></a></td><td class="printindex-index-section"><a href="#Directory-Stack-Builtins">Directory Stack Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-printf"><code>printf</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-pushd"><code>pushd</code></a></td><td class="printindex-index-section"><a href="#Directory-Stack-Builtins">Directory Stack Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-pwd"><code>pwd</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_letter-R">R</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-read"><code>read</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-readarray"><code>readarray</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-readonly"><code>readonly</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-return"><code>return</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_letter-S">S</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-set"><code>set</code></a></td><td class="printindex-index-section"><a href="#The-Set-Builtin">The Set Builtin</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-shift"><code>shift</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-shopt"><code>shopt</code></a></td><td class="printindex-index-section"><a href="#The-Shopt-Builtin">The Shopt Builtin</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-source"><code>source</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-suspend"><code>suspend</code></a></td><td class="printindex-index-section"><a href="#Job-Control-Builtins">Job Control Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_letter-T">T</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-test"><code>test</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-times"><code>times</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-trap"><code>trap</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-type"><code>type</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-typeset"><code>typeset</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_letter-U">U</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-ulimit"><code>ulimit</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-umask"><code>umask</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-unalias"><code>unalias</code></a></td><td class="printindex-index-section"><a href="#Bash-Builtins">Bash Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-unset"><code>unset</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Builtins">Bourne Shell Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Builtin-Index_bt_letter-W">W</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-wait"><code>wait</code></a></td><td class="printindex-index-section"><a href="#Job-Control-Builtins">Job Control Builtins</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| </table> |
| <table class="bt-letters-footer-printindex"><tr><th>Jump to: </th><td><a class="summary-letter-printindex" href="#Builtin-Index_bt_symbol-1"><b>:</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_symbol-2"><b>.</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_symbol-3"><b>[</b></a> |
| |
| <br> |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-A"><b>A</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-B"><b>B</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-C"><b>C</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-D"><b>D</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-E"><b>E</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-F"><b>F</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-G"><b>G</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-H"><b>H</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-J"><b>J</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-K"><b>K</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-L"><b>L</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-M"><b>M</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-P"><b>P</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-R"><b>R</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-S"><b>S</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-T"><b>T</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-U"><b>U</b></a> |
| |
| <a class="summary-letter-printindex" href="#Builtin-Index_bt_letter-W"><b>W</b></a> |
| |
| </td></tr></table> |
| </div> |
| |
| <hr> |
| </div> |
| <div class="appendixsec-level-extent" id="Reserved-Word-Index"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Variable-Index" accesskey="n" rel="next">Parameter and Variable Index</a>, Previous: <a href="#Builtin-Index" accesskey="p" rel="prev">Index of Shell Builtin Commands</a>, Up: <a href="#Indexes" accesskey="u" rel="up">Indexes</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="appendixsec" id="Index-of-Shell-Reserved-Words"><span>D.2 Index of Shell Reserved Words<a class="copiable-link" href="#Index-of-Shell-Reserved-Words"> ¶</a></span></h3> |
| <div class="printindex rw-printindex"> |
| <table class="rw-letters-header-printindex"><tr><th>Jump to: </th><td><a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_symbol-1"><b>!</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_symbol-2"><b>[</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_symbol-3"><b>]</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_symbol-4"><b>{</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_symbol-5"><b>}</b></a> |
| |
| <br> |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_letter-C"><b>C</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_letter-D"><b>D</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_letter-E"><b>E</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_letter-F"><b>F</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_letter-I"><b>I</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_letter-S"><b>S</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_letter-T"><b>T</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_letter-U"><b>U</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_letter-W"><b>W</b></a> |
| |
| </td></tr></table> |
| <table class="rw-entries-printindex" border="0"> |
| <tr><td></td><th class="entries-header-printindex">Index Entry</th><th class="sections-header-printindex">Section</th></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Reserved-Word-Index_rw_symbol-1">!</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_0021"><code>!</code></a></td><td class="printindex-index-section"><a href="#Pipelines">Pipelines</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Reserved-Word-Index_rw_symbol-2">[</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_005b_005b"><code>[[</code></a></td><td class="printindex-index-section"><a href="#Conditional-Constructs">Conditional Constructs</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Reserved-Word-Index_rw_symbol-3">]</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_005d_005d"><code>]]</code></a></td><td class="printindex-index-section"><a href="#Conditional-Constructs">Conditional Constructs</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Reserved-Word-Index_rw_symbol-4">{</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_007b"><code>{</code></a></td><td class="printindex-index-section"><a href="#Command-Grouping">Command Grouping</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Reserved-Word-Index_rw_symbol-5">}</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_007d"><code>}</code></a></td><td class="printindex-index-section"><a href="#Command-Grouping">Command Grouping</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Reserved-Word-Index_rw_letter-C">C</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-case"><code>case</code></a></td><td class="printindex-index-section"><a href="#Conditional-Constructs">Conditional Constructs</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Reserved-Word-Index_rw_letter-D">D</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-do"><code>do</code></a></td><td class="printindex-index-section"><a href="#Looping-Constructs">Looping Constructs</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-done"><code>done</code></a></td><td class="printindex-index-section"><a href="#Looping-Constructs">Looping Constructs</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Reserved-Word-Index_rw_letter-E">E</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-elif"><code>elif</code></a></td><td class="printindex-index-section"><a href="#Conditional-Constructs">Conditional Constructs</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-else"><code>else</code></a></td><td class="printindex-index-section"><a href="#Conditional-Constructs">Conditional Constructs</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-esac"><code>esac</code></a></td><td class="printindex-index-section"><a href="#Conditional-Constructs">Conditional Constructs</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Reserved-Word-Index_rw_letter-F">F</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-fi"><code>fi</code></a></td><td class="printindex-index-section"><a href="#Conditional-Constructs">Conditional Constructs</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-for"><code>for</code></a></td><td class="printindex-index-section"><a href="#Looping-Constructs">Looping Constructs</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-function"><code>function</code></a></td><td class="printindex-index-section"><a href="#Shell-Functions">Shell Functions</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Reserved-Word-Index_rw_letter-I">I</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-if"><code>if</code></a></td><td class="printindex-index-section"><a href="#Conditional-Constructs">Conditional Constructs</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-in"><code>in</code></a></td><td class="printindex-index-section"><a href="#Conditional-Constructs">Conditional Constructs</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Reserved-Word-Index_rw_letter-S">S</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-select"><code>select</code></a></td><td class="printindex-index-section"><a href="#Conditional-Constructs">Conditional Constructs</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Reserved-Word-Index_rw_letter-T">T</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-then"><code>then</code></a></td><td class="printindex-index-section"><a href="#Conditional-Constructs">Conditional Constructs</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-time"><code>time</code></a></td><td class="printindex-index-section"><a href="#Pipelines">Pipelines</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Reserved-Word-Index_rw_letter-U">U</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-until"><code>until</code></a></td><td class="printindex-index-section"><a href="#Looping-Constructs">Looping Constructs</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Reserved-Word-Index_rw_letter-W">W</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-while"><code>while</code></a></td><td class="printindex-index-section"><a href="#Looping-Constructs">Looping Constructs</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| </table> |
| <table class="rw-letters-footer-printindex"><tr><th>Jump to: </th><td><a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_symbol-1"><b>!</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_symbol-2"><b>[</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_symbol-3"><b>]</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_symbol-4"><b>{</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_symbol-5"><b>}</b></a> |
| |
| <br> |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_letter-C"><b>C</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_letter-D"><b>D</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_letter-E"><b>E</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_letter-F"><b>F</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_letter-I"><b>I</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_letter-S"><b>S</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_letter-T"><b>T</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_letter-U"><b>U</b></a> |
| |
| <a class="summary-letter-printindex" href="#Reserved-Word-Index_rw_letter-W"><b>W</b></a> |
| |
| </td></tr></table> |
| </div> |
| |
| <hr> |
| </div> |
| <div class="appendixsec-level-extent" id="Variable-Index"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Function-Index" accesskey="n" rel="next">Function Index</a>, Previous: <a href="#Reserved-Word-Index" accesskey="p" rel="prev">Index of Shell Reserved Words</a>, Up: <a href="#Indexes" accesskey="u" rel="up">Indexes</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="appendixsec" id="Parameter-and-Variable-Index"><span>D.3 Parameter and Variable Index<a class="copiable-link" href="#Parameter-and-Variable-Index"> ¶</a></span></h3> |
| <div class="printindex vr-printindex"> |
| <table class="vr-letters-header-printindex"><tr><th>Jump to: </th><td><a class="summary-letter-printindex" href="#Variable-Index_vr_symbol-1"><b>_</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_symbol-2"><b>-</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_symbol-3"><b>!</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_symbol-4"><b>?</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_symbol-5"><b>@</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_symbol-6"><b>*</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_symbol-7"><b>#</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_symbol-8"><b>$</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_symbol-9"><b>0</b></a> |
| |
| <br> |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-A"><b>A</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-B"><b>B</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-C"><b>C</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-D"><b>D</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-E"><b>E</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-F"><b>F</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-G"><b>G</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-H"><b>H</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-I"><b>I</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-K"><b>K</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-L"><b>L</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-M"><b>M</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-O"><b>O</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-P"><b>P</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-R"><b>R</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-S"><b>S</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-T"><b>T</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-U"><b>U</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-V"><b>V</b></a> |
| |
| </td></tr></table> |
| <table class="vr-entries-printindex" border="0"> |
| <tr><td></td><th class="entries-header-printindex">Index Entry</th><th class="sections-header-printindex">Section</th></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_symbol-1">_</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_005f"><code>_</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_symbol-2">-</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_002d"><code>-</code></a></td><td class="printindex-index-section"><a href="#Special-Parameters">Special Parameters</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_symbol-3">!</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_0021-1"><code>!</code></a></td><td class="printindex-index-section"><a href="#Special-Parameters">Special Parameters</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_symbol-4">?</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_003f"><code>?</code></a></td><td class="printindex-index-section"><a href="#Special-Parameters">Special Parameters</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_symbol-5">@</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_0040"><code>@</code></a></td><td class="printindex-index-section"><a href="#Special-Parameters">Special Parameters</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_symbol-6">*</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_002a"><code>*</code></a></td><td class="printindex-index-section"><a href="#Special-Parameters">Special Parameters</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_symbol-7">#</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_0023"><code>#</code></a></td><td class="printindex-index-section"><a href="#Special-Parameters">Special Parameters</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_symbol-8">$</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_0024"><code>$</code></a></td><td class="printindex-index-section"><a href="#Special-Parameters">Special Parameters</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_0024_005f"><code>$_</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_0024_002d"><code>$-</code></a></td><td class="printindex-index-section"><a href="#Special-Parameters">Special Parameters</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_0024_0021"><code>$!</code></a></td><td class="printindex-index-section"><a href="#Special-Parameters">Special Parameters</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_0024_003f"><code>$?</code></a></td><td class="printindex-index-section"><a href="#Special-Parameters">Special Parameters</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_0024_0040"><code>$@</code></a></td><td class="printindex-index-section"><a href="#Special-Parameters">Special Parameters</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_0024_002a"><code>$*</code></a></td><td class="printindex-index-section"><a href="#Special-Parameters">Special Parameters</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_0024_0023"><code>$#</code></a></td><td class="printindex-index-section"><a href="#Special-Parameters">Special Parameters</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_0024_0024"><code>$$</code></a></td><td class="printindex-index-section"><a href="#Special-Parameters">Special Parameters</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-_00240"><code>$0</code></a></td><td class="printindex-index-section"><a href="#Special-Parameters">Special Parameters</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_symbol-9">0</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-0"><code>0</code></a></td><td class="printindex-index-section"><a href="#Special-Parameters">Special Parameters</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_letter-A">A</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-active_002dregion_002dend_002dcolor"><code>active-region-end-color</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-active_002dregion_002dstart_002dcolor"><code>active-region-start-color</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-auto_005fresume"><code>auto_resume</code></a></td><td class="printindex-index-section"><a href="#Job-Control-Variables">Job Control Variables</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_letter-B">B</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASH"><code>BASH</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASH_005fALIASES"><code>BASH_ALIASES</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASH_005fARGC"><code>BASH_ARGC</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASH_005fARGV"><code>BASH_ARGV</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASH_005fARGV0"><code>BASH_ARGV0</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASH_005fCMDS"><code>BASH_CMDS</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASH_005fCOMMAND"><code>BASH_COMMAND</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASH_005fCOMPAT"><code>BASH_COMPAT</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASH_005fENV"><code>BASH_ENV</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASH_005fEXECUTION_005fSTRING"><code>BASH_EXECUTION_STRING</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASH_005fLINENO"><code>BASH_LINENO</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASH_005fLOADABLES_005fPATH"><code>BASH_LOADABLES_PATH</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASH_005fREMATCH"><code>BASH_REMATCH</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASH_005fSOURCE"><code>BASH_SOURCE</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASH_005fSUBSHELL"><code>BASH_SUBSHELL</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASH_005fVERSINFO"><code>BASH_VERSINFO</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASH_005fVERSION"><code>BASH_VERSION</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASH_005fXTRACEFD"><code>BASH_XTRACEFD</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASHOPTS"><code>BASHOPTS</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-BASHPID"><code>BASHPID</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-bell_002dstyle"><code>bell-style</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-bind_002dtty_002dspecial_002dchars"><code>bind-tty-special-chars</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-blink_002dmatching_002dparen"><code>blink-matching-paren</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_letter-C">C</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-CDPATH"><code>CDPATH</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Variables">Bourne Shell Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-CHILD_005fMAX"><code>CHILD_MAX</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-colored_002dcompletion_002dprefix"><code>colored-completion-prefix</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-colored_002dstats"><code>colored-stats</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-COLUMNS"><code>COLUMNS</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-comment_002dbegin"><code>comment-begin</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-COMP_005fCWORD"><code>COMP_CWORD</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-COMP_005fKEY"><code>COMP_KEY</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-COMP_005fLINE"><code>COMP_LINE</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-COMP_005fPOINT"><code>COMP_POINT</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-COMP_005fTYPE"><code>COMP_TYPE</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-COMP_005fWORDBREAKS"><code>COMP_WORDBREAKS</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-COMP_005fWORDS"><code>COMP_WORDS</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-completion_002ddisplay_002dwidth"><code>completion-display-width</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-completion_002dignore_002dcase"><code>completion-ignore-case</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-completion_002dmap_002dcase"><code>completion-map-case</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-completion_002dprefix_002ddisplay_002dlength"><code>completion-prefix-display-length</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-completion_002dquery_002ditems"><code>completion-query-items</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-COMPREPLY"><code>COMPREPLY</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-convert_002dmeta"><code>convert-meta</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-COPROC"><code>COPROC</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_letter-D">D</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-DIRSTACK"><code>DIRSTACK</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-disable_002dcompletion"><code>disable-completion</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_letter-E">E</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-echo_002dcontrol_002dcharacters"><code>echo-control-characters</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-editing_002dmode"><code>editing-mode</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-EMACS"><code>EMACS</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-emacs_002dmode_002dstring"><code>emacs-mode-string</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-enable_002dactive_002dregion"><code>enable-active-region</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-enable_002dbracketed_002dpaste"><code>enable-bracketed-paste</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-enable_002dkeypad"><code>enable-keypad</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-ENV"><code>ENV</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-EPOCHREALTIME"><code>EPOCHREALTIME</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-EPOCHSECONDS"><code>EPOCHSECONDS</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-EUID"><code>EUID</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-EXECIGNORE"><code>EXECIGNORE</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-expand_002dtilde"><code>expand-tilde</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_letter-F">F</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-FCEDIT"><code>FCEDIT</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-FIGNORE"><code>FIGNORE</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-FUNCNAME"><code>FUNCNAME</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-FUNCNEST"><code>FUNCNEST</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_letter-G">G</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-GLOBIGNORE"><code>GLOBIGNORE</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-GROUPS"><code>GROUPS</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_letter-H">H</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-histchars"><code>histchars</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-HISTCMD"><code>HISTCMD</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-HISTCONTROL"><code>HISTCONTROL</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-HISTFILE"><code>HISTFILE</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-HISTFILESIZE"><code>HISTFILESIZE</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-HISTIGNORE"><code>HISTIGNORE</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-history_002dpreserve_002dpoint"><code>history-preserve-point</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-history_002dsize"><code>history-size</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-HISTSIZE"><code>HISTSIZE</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-HISTTIMEFORMAT"><code>HISTTIMEFORMAT</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-HOME"><code>HOME</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Variables">Bourne Shell Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-horizontal_002dscroll_002dmode"><code>horizontal-scroll-mode</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-HOSTFILE"><code>HOSTFILE</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-HOSTNAME"><code>HOSTNAME</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-HOSTTYPE"><code>HOSTTYPE</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_letter-I">I</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-IFS"><code>IFS</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Variables">Bourne Shell Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-IGNOREEOF"><code>IGNOREEOF</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-input_002dmeta"><code>input-meta</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-INPUTRC"><code>INPUTRC</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-INSIDE_005fEMACS"><code>INSIDE_EMACS</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-isearch_002dterminators"><code>isearch-terminators</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_letter-K">K</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-keymap"><code>keymap</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_letter-L">L</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-LANG"><code>LANG</code></a></td><td class="printindex-index-section"><a href="#Creating-Internationalized-Scripts">Creating Internationalized Scripts</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-LANG-1"><code>LANG</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-LC_005fALL"><code>LC_ALL</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-LC_005fCOLLATE"><code>LC_COLLATE</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-LC_005fCTYPE"><code>LC_CTYPE</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-LC_005fMESSAGES"><code>LC_MESSAGES</code></a></td><td class="printindex-index-section"><a href="#Creating-Internationalized-Scripts">Creating Internationalized Scripts</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-LC_005fMESSAGES-1"><code>LC_MESSAGES</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-LC_005fNUMERIC"><code>LC_NUMERIC</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-LC_005fTIME"><code>LC_TIME</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-LINENO"><code>LINENO</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-LINES"><code>LINES</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_letter-M">M</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-MACHTYPE"><code>MACHTYPE</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-MAIL"><code>MAIL</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Variables">Bourne Shell Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-MAILCHECK"><code>MAILCHECK</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-MAILPATH"><code>MAILPATH</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Variables">Bourne Shell Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-MAPFILE"><code>MAPFILE</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-mark_002dmodified_002dlines"><code>mark-modified-lines</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-mark_002dsymlinked_002ddirectories"><code>mark-symlinked-directories</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-match_002dhidden_002dfiles"><code>match-hidden-files</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-menu_002dcomplete_002ddisplay_002dprefix"><code>menu-complete-display-prefix</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-meta_002dflag"><code>meta-flag</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_letter-O">O</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-OLDPWD"><code>OLDPWD</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-OPTARG"><code>OPTARG</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Variables">Bourne Shell Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-OPTERR"><code>OPTERR</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-OPTIND"><code>OPTIND</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Variables">Bourne Shell Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-OSTYPE"><code>OSTYPE</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-output_002dmeta"><code>output-meta</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_letter-P">P</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-page_002dcompletions"><code>page-completions</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-PATH"><code>PATH</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Variables">Bourne Shell Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-PIPESTATUS"><code>PIPESTATUS</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-POSIXLY_005fCORRECT"><code>POSIXLY_CORRECT</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-PPID"><code>PPID</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-PROMPT_005fCOMMAND"><code>PROMPT_COMMAND</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-PROMPT_005fDIRTRIM"><code>PROMPT_DIRTRIM</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-PS0"><code>PS0</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-PS1"><code>PS1</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Variables">Bourne Shell Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-PS2"><code>PS2</code></a></td><td class="printindex-index-section"><a href="#Bourne-Shell-Variables">Bourne Shell Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-PS3"><code>PS3</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-PS4"><code>PS4</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-PWD"><code>PWD</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_letter-R">R</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-RANDOM"><code>RANDOM</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-READLINE_005fARGUMENT"><code>READLINE_ARGUMENT</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-READLINE_005fLINE"><code>READLINE_LINE</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-READLINE_005fMARK"><code>READLINE_MARK</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-READLINE_005fPOINT"><code>READLINE_POINT</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-REPLY"><code>REPLY</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-revert_002dall_002dat_002dnewline"><code>revert-all-at-newline</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_letter-S">S</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-SECONDS"><code>SECONDS</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-SHELL"><code>SHELL</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-SHELLOPTS"><code>SHELLOPTS</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-SHLVL"><code>SHLVL</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-show_002dall_002dif_002dambiguous"><code>show-all-if-ambiguous</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-show_002dall_002dif_002dunmodified"><code>show-all-if-unmodified</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-show_002dmode_002din_002dprompt"><code>show-mode-in-prompt</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-skip_002dcompleted_002dtext"><code>skip-completed-text</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-SRANDOM"><code>SRANDOM</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_letter-T">T</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-TEXTDOMAIN"><code>TEXTDOMAIN</code></a></td><td class="printindex-index-section"><a href="#Creating-Internationalized-Scripts">Creating Internationalized Scripts</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-TEXTDOMAINDIR"><code>TEXTDOMAINDIR</code></a></td><td class="printindex-index-section"><a href="#Creating-Internationalized-Scripts">Creating Internationalized Scripts</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-TIMEFORMAT"><code>TIMEFORMAT</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-TMOUT"><code>TMOUT</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-TMPDIR"><code>TMPDIR</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_letter-U">U</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-UID"><code>UID</code></a></td><td class="printindex-index-section"><a href="#Bash-Variables">Bash Variables</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Variable-Index_vr_letter-V">V</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-vi_002dcmd_002dmode_002dstring"><code>vi-cmd-mode-string</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-vi_002dins_002dmode_002dstring"><code>vi-ins-mode-string</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-visible_002dstats"><code>visible-stats</code></a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| </table> |
| <table class="vr-letters-footer-printindex"><tr><th>Jump to: </th><td><a class="summary-letter-printindex" href="#Variable-Index_vr_symbol-1"><b>_</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_symbol-2"><b>-</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_symbol-3"><b>!</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_symbol-4"><b>?</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_symbol-5"><b>@</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_symbol-6"><b>*</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_symbol-7"><b>#</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_symbol-8"><b>$</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_symbol-9"><b>0</b></a> |
| |
| <br> |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-A"><b>A</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-B"><b>B</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-C"><b>C</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-D"><b>D</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-E"><b>E</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-F"><b>F</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-G"><b>G</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-H"><b>H</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-I"><b>I</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-K"><b>K</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-L"><b>L</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-M"><b>M</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-O"><b>O</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-P"><b>P</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-R"><b>R</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-S"><b>S</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-T"><b>T</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-U"><b>U</b></a> |
| |
| <a class="summary-letter-printindex" href="#Variable-Index_vr_letter-V"><b>V</b></a> |
| |
| </td></tr></table> |
| </div> |
| |
| <hr> |
| </div> |
| <div class="appendixsec-level-extent" id="Function-Index"> |
| <div class="nav-panel"> |
| <p> |
| Next: <a href="#Concept-Index" accesskey="n" rel="next">Concept Index</a>, Previous: <a href="#Variable-Index" accesskey="p" rel="prev">Parameter and Variable Index</a>, Up: <a href="#Indexes" accesskey="u" rel="up">Indexes</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="appendixsec" id="Function-Index-1"><span>D.4 Function Index<a class="copiable-link" href="#Function-Index-1"> ¶</a></span></h3> |
| <div class="printindex fn-printindex"> |
| <table class="fn-letters-header-printindex"><tr><th>Jump to: </th><td><a class="summary-letter-printindex" href="#Function-Index_fn_letter-A"><b>A</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-B"><b>B</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-C"><b>C</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-D"><b>D</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-E"><b>E</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-F"><b>F</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-G"><b>G</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-H"><b>H</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-I"><b>I</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-K"><b>K</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-M"><b>M</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-N"><b>N</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-O"><b>O</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-P"><b>P</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-Q"><b>Q</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-R"><b>R</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-S"><b>S</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-T"><b>T</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-U"><b>U</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-Y"><b>Y</b></a> |
| |
| </td></tr></table> |
| <table class="fn-entries-printindex" border="0"> |
| <tr><td></td><th class="entries-header-printindex">Index Entry</th><th class="sections-header-printindex">Section</th></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-A">A</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-abort-_0028C_002dg_0029"><code>abort (C-g)</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-accept_002dline-_0028Newline-or-Return_0029"><code>accept-line (Newline or Return)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-History">Commands For History</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-alias_002dexpand_002dline-_0028_0029"><code>alias-expand-line ()</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-B">B</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-backward_002dchar-_0028C_002db_0029"><code>backward-char (C-b)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Moving">Commands For Moving</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-backward_002ddelete_002dchar-_0028Rubout_0029"><code>backward-delete-char (Rubout)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Text">Commands For Text</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-backward_002dkill_002dline-_0028C_002dx-Rubout_0029"><code>backward-kill-line (C-x Rubout)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Killing">Commands For Killing</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-backward_002dkill_002dword-_0028M_002dDEL_0029"><code>backward-kill-word (M-<kbd class="key">DEL</kbd>)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Killing">Commands For Killing</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-backward_002dword-_0028M_002db_0029"><code>backward-word (M-b)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Moving">Commands For Moving</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-beginning_002dof_002dhistory-_0028M_002d_003c_0029"><code>beginning-of-history (M-<)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-History">Commands For History</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-beginning_002dof_002dline-_0028C_002da_0029"><code>beginning-of-line (C-a)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Moving">Commands For Moving</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-bracketed_002dpaste_002dbegin-_0028_0029"><code>bracketed-paste-begin ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Text">Commands For Text</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-C">C</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-call_002dlast_002dkbd_002dmacro-_0028C_002dx-e_0029"><code>call-last-kbd-macro (C-x e)</code></a></td><td class="printindex-index-section"><a href="#Keyboard-Macros">Keyboard Macros</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-capitalize_002dword-_0028M_002dc_0029"><code>capitalize-word (M-c)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Text">Commands For Text</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-character_002dsearch-_0028C_002d_005d_0029"><code>character-search (C-])</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-character_002dsearch_002dbackward-_0028M_002dC_002d_005d_0029"><code>character-search-backward (M-C-])</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-clear_002ddisplay-_0028M_002dC_002dl_0029"><code>clear-display (M-C-l)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Moving">Commands For Moving</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-clear_002dscreen-_0028C_002dl_0029"><code>clear-screen (C-l)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Moving">Commands For Moving</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-complete-_0028TAB_0029"><code>complete (<kbd class="key">TAB</kbd>)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Completion">Commands For Completion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-complete_002dcommand-_0028M_002d_0021_0029"><code>complete-command (M-!)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Completion">Commands For Completion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-complete_002dfilename-_0028M_002d_002f_0029"><code>complete-filename (M-/)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Completion">Commands For Completion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-complete_002dhostname-_0028M_002d_0040_0029"><code>complete-hostname (M-@)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Completion">Commands For Completion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-complete_002dinto_002dbraces-_0028M_002d_007b_0029"><code>complete-into-braces (M-{)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Completion">Commands For Completion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-complete_002dusername-_0028M_002d_007e_0029"><code>complete-username (M-~)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Completion">Commands For Completion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-complete_002dvariable-_0028M_002d_0024_0029"><code>complete-variable (M-$)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Completion">Commands For Completion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-copy_002dbackward_002dword-_0028_0029"><code>copy-backward-word ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Killing">Commands For Killing</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-copy_002dforward_002dword-_0028_0029"><code>copy-forward-word ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Killing">Commands For Killing</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-copy_002dregion_002das_002dkill-_0028_0029"><code>copy-region-as-kill ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Killing">Commands For Killing</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-D">D</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-dabbrev_002dexpand-_0028_0029"><code>dabbrev-expand ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Completion">Commands For Completion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-delete_002dchar-_0028C_002dd_0029"><code>delete-char (C-d)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Text">Commands For Text</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-delete_002dchar_002dor_002dlist-_0028_0029"><code>delete-char-or-list ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Completion">Commands For Completion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-delete_002dhorizontal_002dspace-_0028_0029"><code>delete-horizontal-space ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Killing">Commands For Killing</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-digit_002dargument-_0028M_002d0_002c-M_002d1_002c-_2026-M_002d_002d_0029"><code>digit-argument (<kbd class="kbd">M-0</kbd>, <kbd class="kbd">M-1</kbd>, … <kbd class="kbd">M--</kbd>)</code></a></td><td class="printindex-index-section"><a href="#Numeric-Arguments">Numeric Arguments</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-display_002dshell_002dversion-_0028C_002dx-C_002dv_0029"><code>display-shell-version (C-x C-v)</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-do_002dlowercase_002dversion-_0028M_002dA_002c-M_002dB_002c-M_002dx_002c-_2026_0029"><code>do-lowercase-version (M-A, M-B, M-<var class="var">x</var>, …)</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-downcase_002dword-_0028M_002dl_0029"><code>downcase-word (M-l)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Text">Commands For Text</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-dump_002dfunctions-_0028_0029"><code>dump-functions ()</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-dump_002dmacros-_0028_0029"><code>dump-macros ()</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-dump_002dvariables-_0028_0029"><code>dump-variables ()</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-dynamic_002dcomplete_002dhistory-_0028M_002dTAB_0029"><code>dynamic-complete-history (M-<kbd class="key">TAB</kbd>)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Completion">Commands For Completion</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-E">E</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-edit_002dand_002dexecute_002dcommand-_0028C_002dx-C_002de_0029"><code>edit-and-execute-command (C-x C-e)</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-end_002dkbd_002dmacro-_0028C_002dx-_0029_0029"><code>end-kbd-macro (C-x ))</code></a></td><td class="printindex-index-section"><a href="#Keyboard-Macros">Keyboard Macros</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-end_002dof_002dfile-_0028usually-C_002dd_0029"><code><i class="i">end-of-file</i> (usually C-d)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Text">Commands For Text</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-end_002dof_002dhistory-_0028M_002d_003e_0029"><code>end-of-history (M->)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-History">Commands For History</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-end_002dof_002dline-_0028C_002de_0029"><code>end-of-line (C-e)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Moving">Commands For Moving</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-exchange_002dpoint_002dand_002dmark-_0028C_002dx-C_002dx_0029"><code>exchange-point-and-mark (C-x C-x)</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-F">F</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-fetch_002dhistory-_0028_0029"><code>fetch-history ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-History">Commands For History</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-forward_002dbackward_002ddelete_002dchar-_0028_0029"><code>forward-backward-delete-char ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Text">Commands For Text</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-forward_002dchar-_0028C_002df_0029"><code>forward-char (C-f)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Moving">Commands For Moving</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-forward_002dsearch_002dhistory-_0028C_002ds_0029"><code>forward-search-history (C-s)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-History">Commands For History</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-forward_002dword-_0028M_002df_0029"><code>forward-word (M-f)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Moving">Commands For Moving</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-G">G</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-glob_002dcomplete_002dword-_0028M_002dg_0029"><code>glob-complete-word (M-g)</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-glob_002dexpand_002dword-_0028C_002dx-_002a_0029"><code>glob-expand-word (C-x *)</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-glob_002dlist_002dexpansions-_0028C_002dx-g_0029"><code>glob-list-expansions (C-x g)</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-H">H</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-history_002dand_002dalias_002dexpand_002dline-_0028_0029"><code>history-and-alias-expand-line ()</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-history_002dexpand_002dline-_0028M_002d_005e_0029"><code>history-expand-line (M-^)</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-history_002dsearch_002dbackward-_0028_0029"><code>history-search-backward ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-History">Commands For History</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-history_002dsearch_002dforward-_0028_0029"><code>history-search-forward ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-History">Commands For History</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-history_002dsubstring_002dsearch_002dbackward-_0028_0029"><code>history-substring-search-backward ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-History">Commands For History</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-history_002dsubstring_002dsearch_002dforward-_0028_0029"><code>history-substring-search-forward ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-History">Commands For History</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-I">I</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-insert_002dcomment-_0028M_002d_0023_0029"><code>insert-comment (M-#)</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-insert_002dcompletions-_0028M_002d_002a_0029"><code>insert-completions (M-*)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Completion">Commands For Completion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-insert_002dlast_002dargument-_0028M_002d_002e-or-M_002d_005f_0029"><code>insert-last-argument (M-. or M-_)</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-K">K</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-kill_002dline-_0028C_002dk_0029"><code>kill-line (C-k)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Killing">Commands For Killing</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-kill_002dregion-_0028_0029"><code>kill-region ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Killing">Commands For Killing</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-kill_002dwhole_002dline-_0028_0029"><code>kill-whole-line ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Killing">Commands For Killing</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-kill_002dword-_0028M_002dd_0029"><code>kill-word (M-d)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Killing">Commands For Killing</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-M">M</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-magic_002dspace-_0028_0029"><code>magic-space ()</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-menu_002dcomplete-_0028_0029"><code>menu-complete ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Completion">Commands For Completion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-menu_002dcomplete_002dbackward-_0028_0029"><code>menu-complete-backward ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Completion">Commands For Completion</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-N">N</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-next_002dhistory-_0028C_002dn_0029"><code>next-history (C-n)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-History">Commands For History</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-next_002dscreen_002dline-_0028_0029"><code>next-screen-line ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Moving">Commands For Moving</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-non_002dincremental_002dforward_002dsearch_002dhistory-_0028M_002dn_0029"><code>non-incremental-forward-search-history (M-n)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-History">Commands For History</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-non_002dincremental_002dreverse_002dsearch_002dhistory-_0028M_002dp_0029"><code>non-incremental-reverse-search-history (M-p)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-History">Commands For History</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-O">O</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-operate_002dand_002dget_002dnext-_0028C_002do_0029"><code>operate-and-get-next (C-o)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-History">Commands For History</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-overwrite_002dmode-_0028_0029"><code>overwrite-mode ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Text">Commands For Text</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-P">P</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-possible_002dcommand_002dcompletions-_0028C_002dx-_0021_0029"><code>possible-command-completions (C-x !)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Completion">Commands For Completion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-possible_002dcompletions-_0028M_002d_003f_0029"><code>possible-completions (M-?)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Completion">Commands For Completion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-possible_002dfilename_002dcompletions-_0028C_002dx-_002f_0029"><code>possible-filename-completions (C-x /)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Completion">Commands For Completion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-possible_002dhostname_002dcompletions-_0028C_002dx-_0040_0029"><code>possible-hostname-completions (C-x @)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Completion">Commands For Completion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-possible_002dusername_002dcompletions-_0028C_002dx-_007e_0029"><code>possible-username-completions (C-x ~)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Completion">Commands For Completion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-possible_002dvariable_002dcompletions-_0028C_002dx-_0024_0029"><code>possible-variable-completions (C-x $)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Completion">Commands For Completion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-prefix_002dmeta-_0028ESC_0029"><code>prefix-meta (<kbd class="key">ESC</kbd>)</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-previous_002dhistory-_0028C_002dp_0029"><code>previous-history (C-p)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-History">Commands For History</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-previous_002dscreen_002dline-_0028_0029"><code>previous-screen-line ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Moving">Commands For Moving</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-print_002dlast_002dkbd_002dmacro-_0028_0029"><code>print-last-kbd-macro ()</code></a></td><td class="printindex-index-section"><a href="#Keyboard-Macros">Keyboard Macros</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-Q">Q</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-quoted_002dinsert-_0028C_002dq-or-C_002dv_0029"><code>quoted-insert (C-q or C-v)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Text">Commands For Text</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-R">R</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-re_002dread_002dinit_002dfile-_0028C_002dx-C_002dr_0029"><code>re-read-init-file (C-x C-r)</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-redraw_002dcurrent_002dline-_0028_0029"><code>redraw-current-line ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Moving">Commands For Moving</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-reverse_002dsearch_002dhistory-_0028C_002dr_0029"><code>reverse-search-history (C-r)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-History">Commands For History</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-revert_002dline-_0028M_002dr_0029"><code>revert-line (M-r)</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-S">S</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-self_002dinsert-_0028a_002c-b_002c-A_002c-1_002c-_0021_002c-_2026_0029"><code>self-insert (a, b, A, 1, !, …)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Text">Commands For Text</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-set_002dmark-_0028C_002d_0040_0029"><code>set-mark (C-@)</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-shell_002dbackward_002dkill_002dword-_0028_0029"><code>shell-backward-kill-word ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Killing">Commands For Killing</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-shell_002dbackward_002dword-_0028M_002dC_002db_0029"><code>shell-backward-word (M-C-b)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Moving">Commands For Moving</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-shell_002dexpand_002dline-_0028M_002dC_002de_0029"><code>shell-expand-line (M-C-e)</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-shell_002dforward_002dword-_0028M_002dC_002df_0029"><code>shell-forward-word (M-C-f)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Moving">Commands For Moving</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-shell_002dkill_002dword-_0028M_002dC_002dd_0029"><code>shell-kill-word (M-C-d)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Killing">Commands For Killing</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-shell_002dtranspose_002dwords-_0028M_002dC_002dt_0029"><code>shell-transpose-words (M-C-t)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Killing">Commands For Killing</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-skip_002dcsi_002dsequence-_0028_0029"><code>skip-csi-sequence ()</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-spell_002dcorrect_002dword-_0028C_002dx-s_0029"><code>spell-correct-word (C-x s)</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-start_002dkbd_002dmacro-_0028C_002dx-_0028_0029"><code>start-kbd-macro (C-x ()</code></a></td><td class="printindex-index-section"><a href="#Keyboard-Macros">Keyboard Macros</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-T">T</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-tilde_002dexpand-_0028M_002d_0026_0029"><code>tilde-expand (M-&)</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-transpose_002dchars-_0028C_002dt_0029"><code>transpose-chars (C-t)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Text">Commands For Text</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-transpose_002dwords-_0028M_002dt_0029"><code>transpose-words (M-t)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Text">Commands For Text</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-U">U</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-undo-_0028C_002d_005f-or-C_002dx-C_002du_0029"><code>undo (C-_ or C-x C-u)</code></a></td><td class="printindex-index-section"><a href="#Miscellaneous-Commands">Miscellaneous Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-universal_002dargument-_0028_0029"><code>universal-argument ()</code></a></td><td class="printindex-index-section"><a href="#Numeric-Arguments">Numeric Arguments</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-unix_002dfilename_002drubout-_0028_0029"><code>unix-filename-rubout ()</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Killing">Commands For Killing</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-unix_002dline_002ddiscard-_0028C_002du_0029"><code>unix-line-discard (C-u)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Killing">Commands For Killing</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-unix_002dword_002drubout-_0028C_002dw_0029"><code>unix-word-rubout (C-w)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Killing">Commands For Killing</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-upcase_002dword-_0028M_002du_0029"><code>upcase-word (M-u)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Text">Commands For Text</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Function-Index_fn_letter-Y">Y</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-yank-_0028C_002dy_0029"><code>yank (C-y)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Killing">Commands For Killing</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-yank_002dlast_002darg-_0028M_002d_002e-or-M_002d_005f_0029"><code>yank-last-arg (M-. or M-_)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-History">Commands For History</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-yank_002dnth_002darg-_0028M_002dC_002dy_0029"><code>yank-nth-arg (M-C-y)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-History">Commands For History</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-yank_002dpop-_0028M_002dy_0029"><code>yank-pop (M-y)</code></a></td><td class="printindex-index-section"><a href="#Commands-For-Killing">Commands For Killing</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| </table> |
| <table class="fn-letters-footer-printindex"><tr><th>Jump to: </th><td><a class="summary-letter-printindex" href="#Function-Index_fn_letter-A"><b>A</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-B"><b>B</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-C"><b>C</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-D"><b>D</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-E"><b>E</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-F"><b>F</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-G"><b>G</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-H"><b>H</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-I"><b>I</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-K"><b>K</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-M"><b>M</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-N"><b>N</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-O"><b>O</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-P"><b>P</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-Q"><b>Q</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-R"><b>R</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-S"><b>S</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-T"><b>T</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-U"><b>U</b></a> |
| |
| <a class="summary-letter-printindex" href="#Function-Index_fn_letter-Y"><b>Y</b></a> |
| |
| </td></tr></table> |
| </div> |
| |
| <hr> |
| </div> |
| <div class="appendixsec-level-extent" id="Concept-Index"> |
| <div class="nav-panel"> |
| <p> |
| Previous: <a href="#Function-Index" accesskey="p" rel="prev">Function Index</a>, Up: <a href="#Indexes" accesskey="u" rel="up">Indexes</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Indexes" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <h3 class="appendixsec" id="Concept-Index-1"><span>D.5 Concept Index<a class="copiable-link" href="#Concept-Index-1"> ¶</a></span></h3> |
| <div class="printindex cp-printindex"> |
| <table class="cp-letters-header-printindex"><tr><th>Jump to: </th><td><a class="summary-letter-printindex" href="#Concept-Index_cp_letter-A"><b>A</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-B"><b>B</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-C"><b>C</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-D"><b>D</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-E"><b>E</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-F"><b>F</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-H"><b>H</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-I"><b>I</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-J"><b>J</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-K"><b>K</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-L"><b>L</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-M"><b>M</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-N"><b>N</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-O"><b>O</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-P"><b>P</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-Q"><b>Q</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-R"><b>R</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-S"><b>S</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-T"><b>T</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-V"><b>V</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-W"><b>W</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-Y"><b>Y</b></a> |
| |
| </td></tr></table> |
| <table class="cp-entries-printindex" border="0"> |
| <tr><td></td><th class="entries-header-printindex">Index Entry</th><th class="sections-header-printindex">Section</th></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-A">A</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-alias-expansion">alias expansion</a></td><td class="printindex-index-section"><a href="#Aliases">Aliases</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-arithmetic-evaluation">arithmetic evaluation</a></td><td class="printindex-index-section"><a href="#Shell-Arithmetic">Shell Arithmetic</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-arithmetic-expansion">arithmetic expansion</a></td><td class="printindex-index-section"><a href="#Arithmetic-Expansion">Arithmetic Expansion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-arithmetic_002c-shell">arithmetic, shell</a></td><td class="printindex-index-section"><a href="#Shell-Arithmetic">Shell Arithmetic</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-arrays">arrays</a></td><td class="printindex-index-section"><a href="#Arrays">Arrays</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-B">B</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-background">background</a></td><td class="printindex-index-section"><a href="#Job-Control-Basics">Job Control Basics</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-Bash-configuration">Bash configuration</a></td><td class="printindex-index-section"><a href="#Basic-Installation">Basic Installation</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-Bash-installation">Bash installation</a></td><td class="printindex-index-section"><a href="#Basic-Installation">Basic Installation</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-Bourne-shell">Bourne shell</a></td><td class="printindex-index-section"><a href="#Basic-Shell-Features">Basic Shell Features</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-brace-expansion">brace expansion</a></td><td class="printindex-index-section"><a href="#Brace-Expansion">Brace Expansion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-builtin-1">builtin</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-C">C</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-command-editing">command editing</a></td><td class="printindex-index-section"><a href="#Readline-Bare-Essentials">Readline Bare Essentials</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-command-execution">command execution</a></td><td class="printindex-index-section"><a href="#Command-Search-and-Execution">Command Search and Execution</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-command-expansion">command expansion</a></td><td class="printindex-index-section"><a href="#Simple-Command-Expansion">Simple Command Expansion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-command-history">command history</a></td><td class="printindex-index-section"><a href="#Bash-History-Facilities">Bash History Facilities</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-command-search">command search</a></td><td class="printindex-index-section"><a href="#Command-Search-and-Execution">Command Search and Execution</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-command-substitution">command substitution</a></td><td class="printindex-index-section"><a href="#Command-Substitution">Command Substitution</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-command-timing">command timing</a></td><td class="printindex-index-section"><a href="#Pipelines">Pipelines</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-commands_002c-compound">commands, compound</a></td><td class="printindex-index-section"><a href="#Compound-Commands">Compound Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-commands_002c-conditional">commands, conditional</a></td><td class="printindex-index-section"><a href="#Conditional-Constructs">Conditional Constructs</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-commands_002c-grouping">commands, grouping</a></td><td class="printindex-index-section"><a href="#Command-Grouping">Command Grouping</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-commands_002c-lists">commands, lists</a></td><td class="printindex-index-section"><a href="#Lists">Lists</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-commands_002c-looping">commands, looping</a></td><td class="printindex-index-section"><a href="#Looping-Constructs">Looping Constructs</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-commands_002c-pipelines">commands, pipelines</a></td><td class="printindex-index-section"><a href="#Pipelines">Pipelines</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-commands_002c-shell">commands, shell</a></td><td class="printindex-index-section"><a href="#Shell-Commands">Shell Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-commands_002c-simple">commands, simple</a></td><td class="printindex-index-section"><a href="#Simple-Commands">Simple Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-comments_002c-shell">comments, shell</a></td><td class="printindex-index-section"><a href="#Comments">Comments</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-Compatibility-Level">Compatibility Level</a></td><td class="printindex-index-section"><a href="#Shell-Compatibility-Mode">Shell Compatibility Mode</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-Compatibility-Mode">Compatibility Mode</a></td><td class="printindex-index-section"><a href="#Shell-Compatibility-Mode">Shell Compatibility Mode</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-completion-builtins">completion builtins</a></td><td class="printindex-index-section"><a href="#Programmable-Completion-Builtins">Programmable Completion Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-configuration">configuration</a></td><td class="printindex-index-section"><a href="#Basic-Installation">Basic Installation</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-control-operator">control operator</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-coprocess">coprocess</a></td><td class="printindex-index-section"><a href="#Coprocesses">Coprocesses</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-D">D</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-directory-stack">directory stack</a></td><td class="printindex-index-section"><a href="#The-Directory-Stack">The Directory Stack</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-E">E</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-editing-command-lines">editing command lines</a></td><td class="printindex-index-section"><a href="#Readline-Bare-Essentials">Readline Bare Essentials</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-environment">environment</a></td><td class="printindex-index-section"><a href="#Environment">Environment</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-evaluation_002c-arithmetic">evaluation, arithmetic</a></td><td class="printindex-index-section"><a href="#Shell-Arithmetic">Shell Arithmetic</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-event-designators">event designators</a></td><td class="printindex-index-section"><a href="#Event-Designators">Event Designators</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-execution-environment">execution environment</a></td><td class="printindex-index-section"><a href="#Command-Execution-Environment">Command Execution Environment</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-exit-status">exit status</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-exit-status-1">exit status</a></td><td class="printindex-index-section"><a href="#Exit-Status">Exit Status</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-expansion">expansion</a></td><td class="printindex-index-section"><a href="#Shell-Expansions">Shell Expansions</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-expansion_002c-arithmetic">expansion, arithmetic</a></td><td class="printindex-index-section"><a href="#Arithmetic-Expansion">Arithmetic Expansion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-expansion_002c-brace">expansion, brace</a></td><td class="printindex-index-section"><a href="#Brace-Expansion">Brace Expansion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-expansion_002c-filename">expansion, filename</a></td><td class="printindex-index-section"><a href="#Filename-Expansion">Filename Expansion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-expansion_002c-parameter">expansion, parameter</a></td><td class="printindex-index-section"><a href="#Shell-Parameter-Expansion">Shell Parameter Expansion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-expansion_002c-pathname">expansion, pathname</a></td><td class="printindex-index-section"><a href="#Filename-Expansion">Filename Expansion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-expansion_002c-tilde">expansion, tilde</a></td><td class="printindex-index-section"><a href="#Tilde-Expansion">Tilde Expansion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-expressions_002c-arithmetic">expressions, arithmetic</a></td><td class="printindex-index-section"><a href="#Shell-Arithmetic">Shell Arithmetic</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-expressions_002c-conditional">expressions, conditional</a></td><td class="printindex-index-section"><a href="#Bash-Conditional-Expressions">Bash Conditional Expressions</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-F">F</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-field">field</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-filename">filename</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-filename-expansion">filename expansion</a></td><td class="printindex-index-section"><a href="#Filename-Expansion">Filename Expansion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-foreground">foreground</a></td><td class="printindex-index-section"><a href="#Job-Control-Basics">Job Control Basics</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-functions_002c-shell">functions, shell</a></td><td class="printindex-index-section"><a href="#Shell-Functions">Shell Functions</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-H">H</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-history-builtins">history builtins</a></td><td class="printindex-index-section"><a href="#Bash-History-Builtins">Bash History Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-history-events">history events</a></td><td class="printindex-index-section"><a href="#Event-Designators">Event Designators</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-history-expansion">history expansion</a></td><td class="printindex-index-section"><a href="#History-Interaction">History Interaction</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-history-list">history list</a></td><td class="printindex-index-section"><a href="#Bash-History-Facilities">Bash History Facilities</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-History_002c-how-to-use">History, how to use</a></td><td class="printindex-index-section"><a href="#A-Programmable-Completion-Example">A Programmable Completion Example</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-I">I</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-identifier">identifier</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-initialization-file_002c-readline">initialization file, readline</a></td><td class="printindex-index-section"><a href="#Readline-Init-File">Readline Init File</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-installation">installation</a></td><td class="printindex-index-section"><a href="#Basic-Installation">Basic Installation</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-interaction_002c-readline">interaction, readline</a></td><td class="printindex-index-section"><a href="#Readline-Interaction">Readline Interaction</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-interactive-shell">interactive shell</a></td><td class="printindex-index-section"><a href="#Invoking-Bash">Invoking Bash</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-interactive-shell-1">interactive shell</a></td><td class="printindex-index-section"><a href="#Interactive-Shells">Interactive Shells</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-internationalization">internationalization</a></td><td class="printindex-index-section"><a href="#Locale-Translation">Locale Translation</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-internationalized-scripts">internationalized scripts</a></td><td class="printindex-index-section"><a href="#Creating-Internationalized-Scripts">Creating Internationalized Scripts</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-J">J</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-job">job</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-job-control">job control</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-job-control-1">job control</a></td><td class="printindex-index-section"><a href="#Job-Control-Basics">Job Control Basics</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-K">K</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-kill-ring">kill ring</a></td><td class="printindex-index-section"><a href="#Readline-Killing-Commands">Readline Killing Commands</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-killing-text">killing text</a></td><td class="printindex-index-section"><a href="#Readline-Killing-Commands">Readline Killing Commands</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-L">L</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-localization">localization</a></td><td class="printindex-index-section"><a href="#Locale-Translation">Locale Translation</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-login-shell">login shell</a></td><td class="printindex-index-section"><a href="#Invoking-Bash">Invoking Bash</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-M">M</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-matching_002c-pattern">matching, pattern</a></td><td class="printindex-index-section"><a href="#Pattern-Matching">Pattern Matching</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-metacharacter">metacharacter</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-N">N</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-name">name</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-native-languages">native languages</a></td><td class="printindex-index-section"><a href="#Locale-Translation">Locale Translation</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-notation_002c-readline">notation, readline</a></td><td class="printindex-index-section"><a href="#Readline-Bare-Essentials">Readline Bare Essentials</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-O">O</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-operator_002c-shell">operator, shell</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-P">P</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-parameter-expansion">parameter expansion</a></td><td class="printindex-index-section"><a href="#Shell-Parameter-Expansion">Shell Parameter Expansion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-parameters">parameters</a></td><td class="printindex-index-section"><a href="#Shell-Parameters">Shell Parameters</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-parameters_002c-positional">parameters, positional</a></td><td class="printindex-index-section"><a href="#Positional-Parameters">Positional Parameters</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-parameters_002c-special">parameters, special</a></td><td class="printindex-index-section"><a href="#Special-Parameters">Special Parameters</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-pathname-expansion">pathname expansion</a></td><td class="printindex-index-section"><a href="#Filename-Expansion">Filename Expansion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-pattern-matching">pattern matching</a></td><td class="printindex-index-section"><a href="#Pattern-Matching">Pattern Matching</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-pipeline">pipeline</a></td><td class="printindex-index-section"><a href="#Pipelines">Pipelines</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-POSIX">POSIX</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-POSIX-Mode">POSIX Mode</a></td><td class="printindex-index-section"><a href="#Bash-POSIX-Mode">Bash POSIX Mode</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-process-group">process group</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-process-group-ID">process group ID</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-process-substitution">process substitution</a></td><td class="printindex-index-section"><a href="#Process-Substitution">Process Substitution</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-programmable-completion">programmable completion</a></td><td class="printindex-index-section"><a href="#Programmable-Completion">Programmable Completion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-prompting">prompting</a></td><td class="printindex-index-section"><a href="#Controlling-the-Prompt">Controlling the Prompt</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-Q">Q</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-quoting">quoting</a></td><td class="printindex-index-section"><a href="#Quoting">Quoting</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-quoting_002c-ANSI">quoting, ANSI</a></td><td class="printindex-index-section"><a href="#ANSI_002dC-Quoting">ANSI-C Quoting</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-R">R</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-Readline_002c-how-to-use">Readline, how to use</a></td><td class="printindex-index-section"><a href="#Job-Control-Variables">Job Control Variables</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-redirection">redirection</a></td><td class="printindex-index-section"><a href="#Redirections">Redirections</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-reserved-word">reserved word</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-reserved-words">reserved words</a></td><td class="printindex-index-section"><a href="#Reserved-Words">Reserved Words</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-restricted-shell">restricted shell</a></td><td class="printindex-index-section"><a href="#The-Restricted-Shell">The Restricted Shell</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-return-status">return status</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-S">S</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-shell-arithmetic">shell arithmetic</a></td><td class="printindex-index-section"><a href="#Shell-Arithmetic">Shell Arithmetic</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-shell-function">shell function</a></td><td class="printindex-index-section"><a href="#Shell-Functions">Shell Functions</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-shell-script">shell script</a></td><td class="printindex-index-section"><a href="#Shell-Scripts">Shell Scripts</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-shell-variable">shell variable</a></td><td class="printindex-index-section"><a href="#Shell-Parameters">Shell Parameters</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-shell_002c-interactive">shell, interactive</a></td><td class="printindex-index-section"><a href="#Interactive-Shells">Interactive Shells</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-signal">signal</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-signal-handling">signal handling</a></td><td class="printindex-index-section"><a href="#Signals">Signals</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-special-builtin">special builtin</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-special-builtin-1">special builtin</a></td><td class="printindex-index-section"><a href="#Special-Builtins">Special Builtins</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-startup-files">startup files</a></td><td class="printindex-index-section"><a href="#Bash-Startup-Files">Bash Startup Files</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-string-translations">string translations</a></td><td class="printindex-index-section"><a href="#Creating-Internationalized-Scripts">Creating Internationalized Scripts</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-suspending-jobs">suspending jobs</a></td><td class="printindex-index-section"><a href="#Job-Control-Basics">Job Control Basics</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-T">T</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-tilde-expansion">tilde expansion</a></td><td class="printindex-index-section"><a href="#Tilde-Expansion">Tilde Expansion</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-token">token</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-translation_002c-native-languages">translation, native languages</a></td><td class="printindex-index-section"><a href="#Locale-Translation">Locale Translation</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-V">V</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-variable_002c-shell">variable, shell</a></td><td class="printindex-index-section"><a href="#Shell-Parameters">Shell Parameters</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-variables_002c-readline">variables, readline</a></td><td class="printindex-index-section"><a href="#Readline-Init-File-Syntax">Readline Init File Syntax</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-W">W</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-word">word</a></td><td class="printindex-index-section"><a href="#Definitions">Definitions</a></td></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-word-splitting">word splitting</a></td><td class="printindex-index-section"><a href="#Word-Splitting">Word Splitting</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| <tr><th id="Concept-Index_cp_letter-Y">Y</th></tr> |
| <tr><td></td><td class="printindex-index-entry"><a href="#index-yanking-text">yanking text</a></td><td class="printindex-index-section"><a href="#Readline-Killing-Commands">Readline Killing Commands</a></td></tr> |
| <tr><td colspan="3"><hr></td></tr> |
| </table> |
| <table class="cp-letters-footer-printindex"><tr><th>Jump to: </th><td><a class="summary-letter-printindex" href="#Concept-Index_cp_letter-A"><b>A</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-B"><b>B</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-C"><b>C</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-D"><b>D</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-E"><b>E</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-F"><b>F</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-H"><b>H</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-I"><b>I</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-J"><b>J</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-K"><b>K</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-L"><b>L</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-M"><b>M</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-N"><b>N</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-O"><b>O</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-P"><b>P</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-Q"><b>Q</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-R"><b>R</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-S"><b>S</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-T"><b>T</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-V"><b>V</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-W"><b>W</b></a> |
| |
| <a class="summary-letter-printindex" href="#Concept-Index_cp_letter-Y"><b>Y</b></a> |
| |
| </td></tr></table> |
| </div> |
| |
| </div> |
| </div> |
| </div> |
| |
| |
| |
| </body> |
| </html> |