mirror of
https://github.com/systemd/systemd.git
synced 2024-12-22 17:35:35 +03:00
af080967ba
Fixes: #34949
91 lines
5.0 KiB
XML
91 lines
5.0 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
|
||
<!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-poweroff.service">
|
||
|
||
<refentryinfo>
|
||
<title>systemd-poweroff.service</title>
|
||
<productname>systemd</productname>
|
||
</refentryinfo>
|
||
|
||
<refmeta>
|
||
<refentrytitle>systemd-poweroff.service</refentrytitle>
|
||
<manvolnum>8</manvolnum>
|
||
</refmeta>
|
||
|
||
<refnamediv>
|
||
<refname>systemd-poweroff.service</refname>
|
||
<refname>systemd-halt.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-poweroff.service</filename></para>
|
||
<para><filename>systemd-halt.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>
|
||
<para><filename>/usr/lib/systemd/system-shutdown/</filename></para>
|
||
</refsynopsisdiv>
|
||
|
||
<refsect1>
|
||
<title>Description</title>
|
||
|
||
<para><filename>systemd-poweroff.service</filename> is a system service that is pulled in by
|
||
<filename>poweroff.target</filename> and is responsible for the actual system power-off
|
||
operation. Similarly, <filename>systemd-halt.service</filename> is pulled in by
|
||
<filename>halt.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> binary which is then responsible for the actual
|
||
shutdown. Before shutting down, this binary will try to unmount all remaining file systems (or at least
|
||
remount them read-only), 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>Shortly before executing the actual system power-off/halt/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>poweroff</literal>, <literal>halt</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. (A safety
|
||
timeout of 90s is applied however.) Note that these executables are run <emphasis>after</emphasis> all
|
||
services have been shut down, and after most mounts have been unmounted (the root file system as well as
|
||
<filename>/run/</filename> and various API file systems are still around though). This means any programs
|
||
dropped into this directory must be prepared to run in such a limited execution environment and not rely
|
||
on external services or hierarchies such as <filename>/var/</filename> to be around (or writable).</para>
|
||
|
||
<para>Note that <filename>systemd-poweroff.service</filename> (and the related units) should never be
|
||
executed directly. Instead, trigger system shutdown with a command such as <literal>systemctl
|
||
poweroff</literal>.</para>
|
||
|
||
<para>Another form of shutdown is provided by the
|
||
<citerefentry><refentrytitle>systemd-soft-reboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
|
||
functionality. It reboots only the OS userspace, leaving the kernel, firmware, and hardware as it is.</para>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>See Also</title>
|
||
<para><simplelist type="inline">
|
||
<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
|
||
<member><citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
|
||
<member><citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
|
||
<member><citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry></member>
|
||
<member><citerefentry><refentrytitle>systemd-suspend.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
|
||
<member><citerefentry><refentrytitle>systemd-soft-reboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
|
||
<member><citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
|
||
</simplelist></para>
|
||
</refsect1>
|
||
|
||
</refentry>
|