Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 90 insertions, 0 deletions

diff --git a/man/systemd-poweroff.service.xml b/man/systemd-poweroff.service.xml
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+<?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>