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+<?xml version="1.0"?>
+<!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+<!--
+ This file is part of systemd.
+
+ Copyright 2014 Didier Roche
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+-->
+<refentry id="systemd-machine-id-commit.service">
+
+ <refentryinfo>
+ <title>systemd-machine-id-commit.service</title>
+ <productname>systemd</productname>
+
+ <authorgroup>
+ <author>
+ <contrib>Developer</contrib>
+ <firstname>Didier</firstname>
+ <surname>Roche</surname>
+ <email>didrocks@ubuntu.com</email>
+ </author>
+ </authorgroup>
+ </refentryinfo>
+
+ <refmeta>
+ <refentrytitle>systemd-machine-id-commit.service</refentrytitle>
+ <manvolnum>8</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>systemd-machine-id-commit.service</refname>
+ <refpurpose>Commit a transient machine ID to disk</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <para><filename>systemd-machine-id-commit.service</filename></para>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para><filename>systemd-machine-id-commit.service</filename> is an
+ early boot service responsible for committing transient
+ <filename>/etc/machine-id</filename> files to a writable disk file
+ system. See
+ <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for more information about machine IDs.</para>
+
+ <para>This service is started after
+ <filename>local-fs.target</filename> in case
+ <filename>/etc/machine-id</filename> is a mount point of its own
+ (usually from a memory file system such as
+ <literal>tmpfs</literal>) and /etc is writable. The service will
+ invoke <command>systemd-machine-id-setup --commit</command>, which
+ writes the current transient machine ID to disk and unmount the
+ <filename>/etc/machine-id</filename> file in a race-free manner to
+ ensure that file is always valid and accessible for other
+ processes. See
+ <citerefentry><refentrytitle>systemd-machine-id-setup</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ for details.</para>
+
+ <para>The main use case of this service are systems where
+ <filename>/etc/machine-id</filename> is read-only and initially
+ not initialized. In this case, the system manager will generate a
+ transient machine ID file on a memory file system, and mount it
+ over <filename>/etc/machine-id</filename>, during the early boot
+ phase. This service is then invoked in a later boot phase, as soon
+ as <filename>/etc</filename> has been remounted writable and the
+ ID may thus be committed to disk to make it permanent.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>See Also</title>
+ <para>
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd-machine-id-setup</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd-firstboot</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ </para>
+ </refsect1>
+
+</refentry>