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  <h2>bmgr quickview</h2>
<p><code>bmgr</code> lets you inspect and control the backup/restore system on an Android device.

  <h2>In this document</h2>
  <ol>
<li><a href="#transports">About backup transports</a></li>
<li><a href="#restoresets">About restore sets</a></li>
<li><a href="#backup">Forcing a backup operation</a></li>
<li><a href="#restore">Forcing a restore operation</a></li>
<li><a href="#other">Other commands</a></li>
  </ol>

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<p><code>bmgr</code> is a shell tool that developers can use to interact with the Backup Manager
on Android devices supporting API version 8 or later.  It provides commands for inducing backup
and restore operations on demand so that you do not need to repeatedly wipe data or take similar
intrusive steps to test the operation of an application's backup agent.  These commands are
accessed via the <a href="{@docRoot}guide/developing/tools/adb.html">adb</a> shell.

<p>There are a couple of basic concepts used by the Backup Manager that are built into the way
that <code>bmgr</code> operates.  These are <a href="#transports">backup transports</a> and
<a href="#restoresets">restore sets</a>.


<a name="transports"></a>
<h2>About backup transports</h2>

<p>A <em>backup transport</em> is the code module responsible for moving backup and restore data
to and from some storage location.  A device can have multipe transports installed, though only
one is active at any given time.  Transports are identified by name.  You can see what
transports are available on your device or emulator by running the
<code>bmgr list transports</code> command:

    <pre>adb shell bmgr list transports</pre>

<p>The output of this command is a list of the transports available on the device.  The currently
active transport is flagged with a <code>*</code> character.  Transport names may look like
component names -- for example, <code>android/com.android.internal.backup.LocalTransport</code> --
but they need not be, and the strings are never used as direct class references.  The use of
a component-like naming scheme is simply for purposes of preventing name collisions.

<p>You can change which transport is currently active from the command line as well:

    <pre>adb shell bmgr transport NAME</pre>

<p>where <code>NAME</code> is one of the names as printed by the <code>bmgr list transports</code>
command.  From this point forward, backup and restore operations will be directed through the
newly-selected transport.  Backup state tracking is managed separately for each transport, so
switching back and forth between them will not corrupt the saved state.


<a name="restoresets"></a>
<h2>About restore sets</h2>

<p>All of the application data that a device has written to a given backup transport is tracked
together, and is collectively sometimes called a <em>restore set,</em> because the typical use
of the data set is during restore operations.  Each time a device is initially provisioned, a
new data set is established.  The user can get a listing of all the data sets that can be
restored through the current transport by running this shell command:

    <pre>adb shell bmgr list sets</pre>

<p>The output is listing of available restore sets, one per line.  The first item on each line is
a <em>token,</em> a number in hexadecimal that identifies the restore set to the transport.  After
that is a string that may provide some brief identifying information about the restore set.  Only
the token is actually used within the backup and restore mechanism.


<a name="backup"></a>
<h2>Forcing a backup operation</h2>

<p>Normally, applications notify the backup manager directly that their data has changed, in
response to which the backup manager will make sure to invoke that application's agent when the
next backup operation is run.  You can simulate this manually from the command line if you wish,
by running this shell command:

    <pre>adb shell bmgr backup PACKAGE</pre>

<p><code>PACKAGE</code> is the formal package name of the application you wish to schedule for
backup.  At this point you know that the application's agent will be invoked for backup at some
point in the future, though there is no hard guarantee of when that will occur.  You can force
all pending backup operations to run immediately by using the following command:

    <pre>adb shell bmgr run</pre>

<p>This causes a backup pass to execute immediately, invoking the agents of all applications that
had called <code>BackupManager.dataChanged()</code> since the time of the last backup operation,
plus any applications which had been manually scheduled for backup via
<code>bmgr backup PACKAGE</code>.


<a name="restore"></a>
<h2>Forcing a restore operation</h2>

<p>Unlike backup operations, which are batched together and run on an occasional basis, restore
operations execute immediately.  The backup manager currently provides two kinds of restore
operations.  The first restores an entire device with the data from a given restore set.  This
is typically only performed when a device is first provisioned, to replicate settings and other
such saved state from the user's previous device.  The second kind of restore operation restores
a single application from the <em>active</em> data set; that is, from the data set currently
being written to by backup operations.  This second form is available as part of the public API.
It allows applications to abandon their current data and revert to the last-known-good data as
represented in their current backup image.

<p>A full-system restore operation can be initiated with this shell command:

    <pre>adb shell bmgr restore TOKEN</pre>

<p>where <code>TOKEN</code> is the desired restore set's token as printed out by the <code>bmgr
list sets</code> command.  <strong>Warning!</strong>  This operation will <em>replace</em> the
data of all backup-enabled applications with the contents of the given restore set.  Be careful,
and be aware of the potential consequences.

<p>A single-application restore operation does not reference a restore set token; it always uses
the data from the currently active data set.  You can induce such an operation from the command
line like this:

    <pre>adb shell bmgr restore PACKAGE</pre>

<p><code>PACKAGE</code> is the formal package name of an application that is participating in the
backup/restore mechanism.  The backup manager will immediately instantiate the application's
agent and invoke it for restore.

<a name="other"></a>
<h2>Other commands</h2>

<p>The data for a single application can be erased from the active data set on demand.  This is
very useful during development of backup agents, in case bugs lead you to write corrupt data
or saved state information.  The shell command for wiping an application's data is this:

    <pre>adb shell bmgr wipe PACKAGE</pre>

<p><code>PACKAGE</code> is the formal package name of the application whose data you wish to
erase.  The next backup operation that the application's agent processes will look as
though the application had never backed anything up before.

<p>You can see whether the backup manager is operational at all by running this command:

    <pre>adb shell bmgr enabled</pre>

<p>This might be useful if your application's agent is never being invoked for backup, to verify
whether the operating system thinks it should be performing such operations at all.  You can also
directly disable or enable the backup manager with this command:

    <pre>adb shell bmgr enable BOOLEAN</pre>

<p>where <code>BOOLEAN</code> is either <code>true</code> or <code>false</code>.  This is
equivalent to disabling or enabling backup in the device's main Settings UI.
<strong>Warning!</strong>  When backup is disabled, the current transport will explicitly wipe
the entire active data set from its backend storage.  This is so that when a user says that no,
they do not want their data backed up, the backup manager respects that wish.  No further data
will be saved from the device, and no restore operations will be possible, unless the backup
manager is re-enabled (either through Settings or through the above <code>bmgr</code> command).