1
0
mirror of https://github.com/systemd/systemd.git synced 2024-12-27 07:22:31 +03:00
systemd/man/systemd-dissect.xml
Zbigniew Jędrzejewski-Szmek 7a17e41dcf test: drop whitespace after shell redirection operators
(The one case that is left unchanged is '< <(subcommand)'.)

This way, the style with no gap was already dominant. This way, the reader
immediately knows that ' < ' is a comparison operator and ' << ' is a shift.

In a few cases, replace custom EOF replacement by just EOF. There is no point
in using someting like "_EOL" unless "EOF" appears in the text.
2023-02-06 09:19:04 +01:00

386 lines
21 KiB
XML

<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="systemd-dissect" conditional='HAVE_BLKID'
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>systemd-dissect</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>systemd-dissect</refentrytitle>
<manvolnum>1</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd-dissect</refname>
<refpurpose>Dissect Discoverable Disk Images (DDIs)</refpurpose>
</refnamediv>
<refsynopsisdiv>
<cmdsynopsis>
<command>systemd-dissect <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="plain"><replaceable>IMAGE</replaceable></arg></command>
</cmdsynopsis>
<cmdsynopsis>
<command>systemd-dissect <arg choice="opt" rep="repeat">OPTIONS</arg> <option>--mount</option> <arg choice="plain"><replaceable>IMAGE</replaceable></arg> <arg choice="plain"><replaceable>PATH</replaceable></arg></command>
</cmdsynopsis>
<cmdsynopsis>
<command>systemd-dissect <arg choice="opt" rep="repeat">OPTIONS</arg> <option>--umount</option> <arg choice="plain"><replaceable>PATH</replaceable></arg></command>
</cmdsynopsis>
<cmdsynopsis>
<command>systemd-dissect <arg choice="opt" rep="repeat">OPTIONS</arg> <option>--list</option> <arg choice="plain"><replaceable>IMAGE</replaceable></arg></command>
</cmdsynopsis>
<cmdsynopsis>
<command>systemd-dissect <arg choice="opt" rep="repeat">OPTIONS</arg> <option>--mtree</option> <arg choice="plain"><replaceable>IMAGE</replaceable></arg></command>
</cmdsynopsis>
<cmdsynopsis>
<command>systemd-dissect <arg choice="opt" rep="repeat">OPTIONS</arg> <option>--with</option> <arg choice="plain"><replaceable>IMAGE</replaceable></arg> <arg choice="opt" rep="repeat"><replaceable>COMMAND</replaceable></arg></command>
</cmdsynopsis>
<cmdsynopsis>
<command>systemd-dissect <arg choice="opt" rep="repeat">OPTIONS</arg> <option>--copy-from</option> <arg choice="plain"><replaceable>IMAGE</replaceable></arg> <arg choice="plain"><replaceable>PATH</replaceable></arg> <arg choice="opt"><replaceable>TARGET</replaceable></arg></command>
</cmdsynopsis>
<cmdsynopsis>
<command>systemd-dissect <arg choice="opt" rep="repeat">OPTIONS</arg> <option>--copy-to</option> <arg choice="plain"><replaceable>IMAGE</replaceable></arg> <arg choice="opt"><replaceable>SOURCE</replaceable></arg> <arg choice="plain"><replaceable>PATH</replaceable></arg></command>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><command>systemd-dissect</command> is a tool for introspecting and interacting with file system OS
disk images, specifically Discoverable Disk Images (DDIs). It supports four different operations:</para>
<orderedlist>
<listitem><para>Show general OS image information, including the image's
<citerefentry><refentrytitle>os-release</refentrytitle><manvolnum>5</manvolnum></citerefentry> data,
machine ID, partition information and more.</para></listitem>
<listitem><para>Mount an OS image to a local directory. In this mode it will dissect the OS image and
mount the included partitions according to their designation onto a directory and possibly
sub-directories.</para></listitem>
<listitem><para>Unmount an OS image from a local directory. In this mode it will recursively unmount
the mounted partitions and remove the underlying loop device, including all the partition sub-devices.
</para></listitem>
<listitem><para>Copy files and directories in and out of an OS image.</para></listitem>
</orderedlist>
<para>The tool may operate on three types of OS images:</para>
<orderedlist>
<listitem><para>OS disk images containing a GPT partition table envelope, with partitions marked
according to the <ulink url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">Discoverable Partitions
Specification</ulink>.</para></listitem>
<listitem><para>OS disk images containing just a plain file-system without an enveloping partition
table. (This file system is assumed to be the root file system of the OS.)</para></listitem>
<listitem><para>OS disk images containing a GPT or MBR partition table, with a single
partition only. (This partition is assumed to contain the root file system of the OS.)</para></listitem>
</orderedlist>
<para>OS images may use any kind of Linux-supported file systems. In addition they may make use of LUKS
disk encryption, and contain Verity integrity information. Note that qualifying OS images may be booted
with <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
<option>--image=</option> switch, and be used as root file system for system service using the
<varname>RootImage=</varname> unit file setting, see
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
<para>Note that the partition table shown when invoked without command switch (as listed below) does not
necessarily show all partitions included in the image, but just the partitions that are understood and
considered part of an OS disk image. Specifically, partitions of unknown types are ignored, as well as
duplicate partitions (i.e. more than one per partition type), as are root and <filename>/usr/</filename>
partitions of architectures not compatible with the local system. In other words: this tool will display
what it operates with when mounting the image. To display the complete list of partitions use a tool such
as <citerefentry
project='man-pages'><refentrytitle>fdisk</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
</refsect1>
<refsect1>
<title>Commands</title>
<para>If neither of the command switches listed below are passed the specified disk image is opened and
general information about the image and the contained partitions and their use is shown.</para>
<variablelist>
<varlistentry>
<term><option>--mount</option></term>
<term><option>-m</option></term>
<listitem><para>Mount the specified OS image to the specified directory. This will dissect the image,
determine the OS root file system — as well as possibly other partitions — and mount them to the
specified directory. If the OS image contains multiple partitions marked with the <ulink
url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">Discoverable Partitions Specification</ulink>
multiple nested mounts are established. This command expects two arguments: a path to an image file
and a path to a directory where to mount the image.</para>
<para>To unmount an OS image mounted like this use the <option>--umount</option> operation.</para>
<para>When the OS image contains LUKS encrypted or Verity integrity protected file systems
appropriate volumes are automatically set up and marked for automatic disassembly when the image is
unmounted.</para>
<para>The OS image may either be specified as path to an OS image stored in a regular file or may
refer to block device node (in the latter case the block device must be the "whole" device, i.e. not
a partition device). (The other supported commands described here support this, too.)</para>
<para>All mounted file systems are checked with the appropriate <citerefentry
project='man-pages'><refentrytitle>fsck</refentrytitle><manvolnum>8</manvolnum></citerefentry>
implementation in automatic fixing mode, unless explicitly turned off (<option>--fsck=no</option>) or
read-only operation is requested (<option>--read-only</option>).</para></listitem>
</varlistentry>
<varlistentry>
<term><option>-M</option></term>
<listitem><para>This is a shortcut for <option>--mount --mkdir</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--umount</option></term>
<term><option>-u</option></term>
<listitem><para>Unmount an OS image from the specified directory. This command expects one argument:
a directory where an OS image was mounted.</para>
<para>All mounted partitions will be recursively unmounted, and the underlying loop device will be
removed, along with all it's partition sub-devices.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>-U</option></term>
<listitem><para>This is a shortcut for <option>--umount --rmdir</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--list</option></term>
<term><option>-l</option></term>
<listitem><para>Prints the paths of all the files and directories in the specified OS image to
standard output.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--mtree</option></term>
<term><option>-l</option></term>
<listitem><para>Generates a BSD <citerefentry
project='die-net'><refentrytitle>mtree</refentrytitle><manvolnum>8</manvolnum></citerefentry>
compatible file manifest of the specified disk image. This is useful for comparing disk image
contents in detail, including inode information and other metadata. While the generated manifest will
contain detailed inode information, it currently excludes extended attributes, file system
capabilities, MAC labels, <citerefentry
project='man-pages'><refentrytitle>chattr</refentrytitle><manvolnum>1</manvolnum></citerefentry> file
flags, btrfs subvolume information, and various other file metadata. File content information is
shown via a SHA256 digest. Additional fields might be added in future. Note that inode information
such as link counts, inode numbers and timestamps is excluded from the output on purpose, as it
typically complicates reproducibility.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--with</option></term>
<listitem><para>Runs the specified command with the specified OS image mounted. This will mount the
image to a temporary directory, switch the current working directory to it, and invoke the specified
command line as child process. Once the process ends it will unmount the image again, and remove the
temporary directory. If no command is specified a shell is invoked. The image is mounted writable,
use <option>--read-only</option> to switch to read-only operation. The invoked process will have the
<varname>$SYSTEMD_DISSECT_ROOT</varname> environment variable set, containing the absolute path name
of the temporary mount point, i.e. the same directory that is set as the current working
directory.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--copy-from</option></term>
<term><option>-x</option></term>
<listitem><para>Copies a file or directory from the specified OS image into the specified location on
the host file system. Expects three arguments: a path to an image file, a source path (relative to
the image's root directory) and a destination path (relative to the current working directory, or an
absolute path, both outside of the image). If the destination path is omitted or specified as dash
(<literal>-</literal>), the specified file is written to standard output. If the source path in the
image file system refers to a regular file it is copied to the destination path. In this case access
mode, extended attributes and timestamps are copied as well, but file ownership is not. If the source
path in the image refers to a directory, it is copied to the destination path, recursively with all
containing files and directories. In this case the file ownership is copied too.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--copy-to</option></term>
<term><option>-a</option></term>
<listitem><para>Copies a file or directory from the specified location in the host file system into
the specified OS image. Expects three arguments: a path to an image file, a source path (relative to
the current working directory, or an absolute path, both outside of the image) and a destination path
(relative to the image's root directory). If the source path is omitted or specified as dash
(<literal>-</literal>), the data to write is read from standard input. If the source path in the host
file system refers to a regular file, it is copied to the destination path. In this case access mode,
extended attributes and timestamps are copied as well, but file ownership is not. If the source path
in the host file system refers to a directory it is copied to the destination path, recursively with
all containing files and directories. In this case the file ownership is copied
too.</para>
<para>As with <option>--mount</option> file system checks are implicitly run before the copy
operation begins.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--discover</option></term>
<listitem><para>Show a list of DDIs in well-known directories. This will show machine, portable
service and system extension disk images in the usual directories
<filename>/usr/lib/machines/</filename>, <filename>/usr/lib/portables/</filename>,
<filename>/usr/lib/extensions/</filename>, <filename>/var/lib/machines/</filename>,
<filename>/var/lib/portables/</filename>, <filename>/var/lib/extensions/</filename> and so
on.</para></listitem>
</varlistentry>
<xi:include href="standard-options.xml" xpointer="help" />
<xi:include href="standard-options.xml" xpointer="version" />
</variablelist>
</refsect1>
<refsect1>
<title>Options</title>
<para>The following options are understood:</para>
<variablelist>
<varlistentry>
<term><option>--read-only</option></term>
<term><option>-r</option></term>
<listitem><para>Operate in read-only mode. By default <option>--mount</option> will establish
writable mount points. If this option is specified they are established in read-only mode
instead.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--fsck=no</option></term>
<listitem><para>Turn off automatic file system checking. By default when an image is accessed for
writing (by <option>--mount</option> or <option>--copy-to</option>) the file systems contained in the
OS image are automatically checked using the appropriate <citerefentry
project='man-pages'><refentrytitle>fsck</refentrytitle><manvolnum>8</manvolnum></citerefentry>
command, in automatic fixing mode. This behavior may be switched off using
<option>--fsck=no</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--growfs=no</option></term>
<listitem><para>Turn off automatic growing of accessed file systems to their partition size, if
marked for that in the GPT partition table. By default when an image is accessed for writing (by
<option>--mount</option> or <option>--copy-to</option>) the file systems contained in the OS image
are automatically grown to their partition sizes, if bit 59 in the GPT partition flags is set for
partition types that are defined by the <ulink
url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">Discoverable Partitions Specification</ulink>. This
behavior may be switched off using <option>--growfs=no</option>. File systems are grown automatically
on access if all of the following conditions are met:</para>
<orderedlist>
<listitem><para>The file system is mounted writable</para></listitem>
<listitem><para>The file system currently is smaller than the partition it is contained in (and thus can be grown)</para></listitem>
<listitem><para>The image contains a GPT partition table</para></listitem>
<listitem><para>The file system is stored on a partition defined by the Discoverable Partitions Specification</para></listitem>
<listitem><para>Bit 59 of the GPT partition flags for this partition is set, as per specification</para></listitem>
<listitem><para>The <option>--growfs=no</option> option is not passed.</para></listitem>
</orderedlist>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--mkdir</option></term>
<listitem><para>If combined with <option>--mount</option> the directory to mount the OS image to is
created if it is missing. Note that the directory is not automatically removed when the disk image is
unmounted again.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--rmdir</option></term>
<listitem><para>If combined with <option>--umount</option> the specified directory where the OS image
is mounted is removed after unmounting the OS image.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--discard=</option></term>
<listitem><para>Takes one of <literal>disabled</literal>, <literal>loop</literal>,
<literal>all</literal>, <literal>crypto</literal>. If <literal>disabled</literal> the image is
accessed with empty block discarding turned off. If <literal>loop</literal> discarding is enabled if
operating on a regular file. If <literal>crypt</literal> discarding is enabled even on encrypted file
systems. If <literal>all</literal> discarding is unconditionally enabled.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--in-memory</option></term>
<listitem><para>If specified an in-memory copy of the specified disk image is used. This may be used
to operate with write-access on a (possibly read-only) image, without actually modifying the original
file. This may also be used in order to operate on a disk image without keeping the originating file
system busy, in order to allow it to be unmounted.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--root-hash=</option></term>
<term><option>--root-hash-sig=</option></term>
<term><option>--verity-data=</option></term>
<listitem><para>Configure various aspects of Verity data integrity for the OS image. Option
<option>--root-hash=</option> specifies a hex-encoded top-level Verity hash to use for setting up the
Verity integrity protection. Option <option>--root-hash-sig=</option> specifies the path to a file
containing a PKCS#7 signature for the hash. This signature is passed to the kernel during activation,
which will match it against signature keys available in the kernel keyring. Option
<option>--verity-data=</option> specifies a path to a file with the Verity data to use for the OS
image, in case it is stored in a detached file. It is recommended to embed the Verity data directly
in the image, using the Verity mechanisms in the <ulink
url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">Discoverable Partitions Specification</ulink>.
</para></listitem>
</varlistentry>
<xi:include href="standard-options.xml" xpointer="no-pager" />
<xi:include href="standard-options.xml" xpointer="no-legend" />
<xi:include href="standard-options.xml" xpointer="json" />
</variablelist>
</refsect1>
<refsect1>
<title>Exit status</title>
<para>On success, 0 is returned, a non-zero failure code otherwise. If the <option>--with</option>
command is used the exit status of the invoked command is propagated.</para>
</refsect1>
<refsect1>
<title>Examples</title>
<example>
<title>Generate a tarball from an OS disk image</title>
<programlisting>$ systemd-dissect --with foo.raw tar cz . >foo.tar.gz</programlisting>
</example>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<ulink url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">Discoverable Partitions Specification</ulink>,
<citerefentry project='man-pages'><refentrytitle>umount</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>fdisk</refentrytitle><manvolnum>8</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>