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<?xml version='1.0'?>
<!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+ -->
<refentry id="systemd-machine-id-setup"
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>systemd-machine-id-setup</title>
<productname>systemd</productname>
</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://systemd.io/CONTAINER_INTERFACE">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>
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