man: deemphasize "halt"

Systemd documents "halt" as the primary shutdown mechanism, redirecting
"reboot" and "shutdown" to the halt(8), but halt is a really strange and
obsolete concept. Who would want to really keep their machine running after
shutdown? I expect that halting is almost unused. Let's at least make it less
prominent in the docs.

While at it, use "power off" for a verb and "power-off" for noun (but "poweroff"
of the actual command name).

1 files changed, 92 insertions, 0 deletions

diff --git a/man/systemd-poweroff.service.xml b/man/systemd-poweroff.service.xml
new file mode 100644
index 0000000000..9adfcc5af0
--- /dev/null
+++ b/man/systemd-poweroff.service.xml
@@ -0,0 +1,92 @@
+<?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,
+    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
+    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.</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>
+  </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>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+    </para>
+  </refsect1>
+
+</refentry>