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diff --git a/man/systemd-poweroff.service.xml b/man/systemd-poweroff.service.xml new file mode 100644 index 0000000..b430170 --- /dev/null +++ b/man/systemd-poweroff.service.xml @@ -0,0 +1,90 @@ +<?xml version='1.0'?> <!--*-nxml-*--> +<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" + "http://www.oasis-open.org/docbook/xml/4.2/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> tool 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. Note that + these executables are run <emphasis>after</emphasis> all services have been shut down, and after most + mounts have been detached (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> + <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>, + <citerefentry><refentrytitle>systemd-soft-reboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, + <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry> + </para> + </refsect1> + +</refentry> |