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systemd-stable/man/systemd-machine-id-commit.service.xml
Tom Gundersen 12b42c7667 man: revert dynamic paths for split-usr setups
This did not really work out as we had hoped. Trying to do this upstream
introduced several problems that probably makes it better suited as a
downstream patch after all. At any rate, it is not releaseable in the
current state, so we at least need to revert this before the release.

 * by adjusting the path to binaries, but not do the same thing to the
   search path we end up with inconsistent man-pages. Adjusting the search
   path too would be quite messy, and it is not at all obvious that this is
   worth the effort, but at any rate it would have to be done before we
   could ship this.

 * this means that distributed man-pages does not make sense as they depend
   on config options, and for better or worse we are still distributing
   man pages, so that is something that definitely needs sorting out before
   we could ship with this patch.

 * we have long held that split-usr is only minimally supported in order
   to boot, and something we hope will eventually go away. So before we start
   adding even more magic/effort in order to make this work nicely, we should
   probably question if it makes sense at all.
2015-06-18 19:47:44 +02:00

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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">
<!--
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Copyright 2014 Didier Roche
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<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 transient machine-id to disk</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>systemd-machine-id-commit.service</filename></para>
<para><filename>/usr/lib/systemd/systemd-machine-id-commit</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><filename>systemd-machine-id-commit.service</filename> is a
service responsible for committing any transient
<filename>/etc/machine-id</filename> file to a writable file
system. See
<citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for more information about this file.</para>
<para>This service is started shortly after
<filename>local-fs.target</filename> if
<filename>/etc/machine-id</filename> is an independent mount point
(probably a tmpfs one) and /etc is writable.
<command>systemd-machine-id-commit</command> will then write
current machine ID to disk and unmount the transient
<filename>/etc/machine-id</filename> file in a race-free manner to
ensure that file is always valid for other processes.</para>
<para>Note that the traditional way to initialize the machine ID
in <filename>/etc/machine-id</filename> is to use
<command>systemd-machine-id-setup</command> by system installer
tools. You can also use
<citerefentry><refentrytitle>systemd-firstboot</refentrytitle><manvolnum>1</manvolnum></citerefentry>
to initialize the machine ID on mounted (but not booted) system
images. The main use case for that service is
<filename>/etc/machine-id</filename> being an empty file at boot
and initrd chaining to systemd giving it a read only file system
that will be turned read-write later during the boot
process.</para>
<para>There is no consequence if that service fails other than a
newer machine-id will be generated during next system boot.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-machine-id-commit</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>