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systemd/man/systemd-halt.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">
<!--
This file is part of systemd.
Copyright 2012 Lennart Poettering
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
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systemd is distributed in the hope that it will be useful, but
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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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-halt.service">
<refentryinfo>
<title>systemd-halt.service</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>systemd-halt.service</refentrytitle>
<manvolnum>8</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd-halt.service</refname>
<refname>systemd-poweroff.service</refname>
<refname>systemd-reboot.service</refname>
<refname>systemd-kexec.service</refname>
<refname>systemd-shutdown</refname>
<refpurpose>System shutdown logic</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>systemd-halt.service</filename></para>
<para><filename>systemd-poweroff.service</filename></para>
<para><filename>systemd-reboot.service</filename></para>
<para><filename>systemd-kexec.service</filename></para>
<para><filename>/usr/lib/systemd/systemd-shutdown</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><filename>systemd-halt.service</filename> is a system
service that is pulled in by <filename>halt.target</filename> and
is responsible for the actual system halt. Similarly,
<filename>systemd-poweroff.service</filename> is pulled in by
<filename>poweroff.target</filename>,
<filename>systemd-reboot.service</filename> by
<filename>reboot.target</filename> and
<filename>systemd-kexec.service</filename> by
<filename>kexec.target</filename> to execute the respective
actions.</para>
<para>When these services are run, they ensure that PID 1 is
replaced by the
<filename>/usr/lib/systemd/systemd-shutdown</filename> tool which
is then responsible for the actual shutdown. Before shutting down,
this binary will try to unmount all remaining file systems,
disable all remaining swap devices, detach all remaining storage
devices and kill all remaining processes.</para>
<para>It is necessary to have this code in a separate binary
because otherwise rebooting after an upgrade might be broken — the
running PID 1 could still depend on libraries which are not
available any more, thus keeping the file system busy, which then
cannot be re-mounted read-only.</para>
<para>Immediately before executing the actual system
halt/poweroff/reboot/kexec <filename>systemd-shutdown</filename>
will run all executables in
<filename>/usr/lib/systemd/system-shutdown/</filename> and pass
one arguments to them: either <literal>halt</literal>,
<literal>poweroff</literal>, <literal>reboot</literal> or
<literal>kexec</literal>, depending on the chosen action. All
executables in this directory are executed in parallel, and
execution of the action is not continued before all executables
finished.</para>
<para>Note that <filename>systemd-halt.service</filename> (and the
related units) should never be executed directly. Instead, trigger
system shutdown with a command such as <literal>systemctl
halt</literal> or suchlike.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-suspend.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>