Systemd/man/systemd-halt.service.xml

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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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<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. Similar,
<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>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>