systemd/man/systemd-machine-id-setup.xml
Lennart Poettering 818bf54632 tree-wide: drop 'This file is part of systemd' blurb
This part of the copyright blurb stems from the GPL use recommendations:

https://www.gnu.org/licenses/gpl-howto.en.html

The concept appears to originate in times where version control was per
file, instead of per tree, and was a way to glue the files together.
Ultimately, we nowadays don't live in that world anymore, and this
information is entirely useless anyway, as people are very welcome to
copy these files into any projects they like, and they shouldn't have to
change bits that are part of our copyright header for that.

hence, let's just get rid of this old cruft, and shorten our codebase a
bit.
2018-06-14 10:20:20 +02:00

172 lines
6.3 KiB
XML

<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
SPDX-License-Identifier: LGPL-2.1+
Copyright 2012 Lennart Poettering
-->
<refentry id="systemd-machine-id-setup"
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>systemd-machine-id-setup</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
<author>
<contrib>Developer</contrib>
<firstname>Didier</firstname>
<surname>Roche</surname>
<email>didrocks@ubuntu.com</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>systemd-machine-id-setup</refentrytitle>
<manvolnum>1</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd-machine-id-setup</refname>
<refpurpose>Initialize the machine ID in /etc/machine-id</refpurpose>
</refnamediv>
<refsynopsisdiv>
<cmdsynopsis>
<command>systemd-machine-id-setup</command>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><command>systemd-machine-id-setup</command> may be used by
system installer tools to initialize the machine ID stored in
<filename>/etc/machine-id</filename> at install time, with a
provisioned or randomly generated ID. See
<citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for more information about this file.</para>
<para>If the tool is invoked without the <option>--commit</option>
switch, <filename>/etc/machine-id</filename> is initialized with a
valid, new machined ID if it is missing or empty. The new machine
ID will be acquired in the following fashion:</para>
<orderedlist>
<listitem><para>If a valid D-Bus machine ID is already
configured for the system, the D-Bus machine ID is copied and
used to initialize the machine ID in
<filename>/etc/machine-id</filename>.</para></listitem>
<listitem><para>If run inside a KVM virtual machine and a UUID
is configured (via the <option>-uuid</option>
option), this UUID is used to initialize the machine ID. The
caller must ensure that the UUID passed is sufficiently unique
and is different for every booted instance of the
VM.</para></listitem>
<listitem><para>Similarly, if run inside a Linux container
environment and a UUID is configured for the container, this is
used to initialize the machine ID. For details, see the
documentation of the <ulink
url="https://www.freedesktop.org/wiki/Software/systemd/ContainerInterface">Container
Interface</ulink>.</para></listitem>
<listitem><para>Otherwise, a new ID is randomly
generated.</para></listitem>
</orderedlist>
<para>The <option>--commit</option> switch may be used to commit a
transient machined ID to disk, making it persistent. For details,
see below.</para>
<para>Use
<citerefentry><refentrytitle>systemd-firstboot</refentrytitle><manvolnum>1</manvolnum></citerefentry>
to initialize the machine ID on mounted (but not booted) system
images.</para>
</refsect1>
<refsect1>
<title>Options</title>
<para>The following options are understood:</para>
<variablelist>
<varlistentry>
<term><option>--root=<replaceable>root</replaceable></option></term>
<listitem><para>Takes a directory path as argument. All paths
operated will be prefixed with the given alternate
<replaceable>root</replaceable> path, including the path for
<filename>/etc/machine-id</filename> itself.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--commit</option></term>
<listitem><para>Commit a transient machine ID to disk. This
command may be used to convert a transient machine ID into a
persistent one. A transient machine ID file is one that was
bind mounted from a memory file system (usually
<literal>tmpfs</literal>) to
<filename>/etc/machine-id</filename> during the early phase of
the boot process. This may happen because
<filename>/etc</filename> is initially read-only and was
missing a valid machine ID file at that point.</para>
<para>This command will execute no operation if
<filename>/etc/machine-id</filename> is not mounted from a
memory file system, or if <filename>/etc</filename> is
read-only. The command will write the current transient
machine ID to disk and unmount the
<filename>/etc/machine-id</filename> mount point in a
race-free manner to ensure that this file is always valid and
accessible for other processes.</para>
<para>This command is primarily used by the
<citerefentry><refentrytitle>systemd-machine-id-commit.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
early boot service.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--print</option></term>
<listitem><para>Print the machine ID generated or committed after the operation is complete.</para></listitem>
</varlistentry>
<xi:include href="standard-options.xml" xpointer="help" />
<xi:include href="standard-options.xml" xpointer="version" />
</variablelist>
</refsect1>
<refsect1>
<title>Exit status</title>
<para>On success, 0 is returned, a non-zero failure code
otherwise.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-machine-id-commit.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry project='dbus'><refentrytitle>dbus-uuidgen</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-firstboot</refentrytitle><manvolnum>1</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>