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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
  "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->

<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 machine 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 machine ID is stored in <filename>/run/machine-id</filename>, the machine ID
      is copied and used to initialize the machine ID in <filename>/etc/machine-id</filename>. This step is
      skipped if <option>--root=</option> is specified or running in a chroot environment.</para></listitem>

      <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 a valid machine ID is provided through <option>system.machine_id</option> credential,
      the machine ID is copied and used to initialize the machine ID in <filename>/etc/machine-id</filename>.
      This step is skipped if <option>--root=</option> is specified or running in a chroot environment.
      </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. This
      step is skipped if <option>--root=</option> is specified or running in a chroot environment.
      </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>. This step is skipped if
      <option>--root=</option> is specified or running in a chroot environment.</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>path</replaceable></option></term>
        <listitem><para>Takes a directory path as argument. All paths operated on will be prefixed with the
        given alternate <replaceable>root</replaceable> path, including the path for
        <filename>/etc/machine-id</filename> itself.</para>

        <xi:include href="version-info.xml" xpointer="v212"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--image=<replaceable>path</replaceable></option></term>
        <listitem><para>Takes a path to a device node or regular file as argument. This is similar to
        <option>--root=</option> as described above, but operates on a disk image instead of a directory
        tree.</para>

        <xi:include href="version-info.xml" xpointer="v249"/></listitem>
      </varlistentry>

      <xi:include href="standard-options.xml" xpointer="image-policy-open" />

      <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>

        <xi:include href="version-info.xml" xpointer="v227"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--print</option></term>

        <listitem><para>Print the machine ID generated or committed after the operation is complete.</para>

        <xi:include href="version-info.xml" xpointer="v231"/></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><simplelist type="inline">
      <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>systemd-machine-id-commit.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
      <member><citerefentry project='dbus'><refentrytitle>dbus-uuidgen</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>systemd-firstboot</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
    </simplelist></para>
  </refsect1>

</refentry>
