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1 | <?xml version='1.0'?> <!--*-nxml-*--> |
2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
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4 | |
5 | <!-- | |
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6 | SPDX-License-Identifier: LGPL-2.1+ |
7 | ||
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8 | This file is part of systemd. |
9 | ||
10 | Copyright 2012 Lennart Poettering | |
11 | ||
12 | systemd is free software; you can redistribute it and/or modify it | |
13 | under the terms of the GNU Lesser General Public License as published by | |
14 | the Free Software Foundation; either version 2.1 of the License, or | |
15 | (at your option) any later version. | |
16 | ||
17 | systemd is distributed in the hope that it will be useful, but | |
18 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
20 | Lesser General Public License for more details. | |
21 | ||
22 | You should have received a copy of the GNU Lesser General Public License | |
23 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
24 | --> | |
25 | ||
26 | <refentry id="systemd-halt.service"> | |
27 | ||
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28 | <refentryinfo> |
29 | <title>systemd-halt.service</title> | |
30 | <productname>systemd</productname> | |
31 | ||
32 | <authorgroup> | |
33 | <author> | |
34 | <contrib>Developer</contrib> | |
35 | <firstname>Lennart</firstname> | |
36 | <surname>Poettering</surname> | |
37 | <email>lennart@poettering.net</email> | |
38 | </author> | |
39 | </authorgroup> | |
40 | </refentryinfo> | |
41 | ||
42 | <refmeta> | |
43 | <refentrytitle>systemd-halt.service</refentrytitle> | |
44 | <manvolnum>8</manvolnum> | |
45 | </refmeta> | |
46 | ||
47 | <refnamediv> | |
48 | <refname>systemd-halt.service</refname> | |
49 | <refname>systemd-poweroff.service</refname> | |
50 | <refname>systemd-reboot.service</refname> | |
51 | <refname>systemd-kexec.service</refname> | |
52 | <refname>systemd-shutdown</refname> | |
53 | <refpurpose>System shutdown logic</refpurpose> | |
54 | </refnamediv> | |
55 | ||
56 | <refsynopsisdiv> | |
57 | <para><filename>systemd-halt.service</filename></para> | |
58 | <para><filename>systemd-poweroff.service</filename></para> | |
59 | <para><filename>systemd-reboot.service</filename></para> | |
60 | <para><filename>systemd-kexec.service</filename></para> | |
12b42c76 | 61 | <para><filename>/usr/lib/systemd/systemd-shutdown</filename></para> |
7fbbf283 | 62 | <para><filename>/usr/lib/systemd/system-shutdown/</filename></para> |
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63 | </refsynopsisdiv> |
64 | ||
65 | <refsect1> | |
66 | <title>Description</title> | |
67 | ||
68 | <para><filename>systemd-halt.service</filename> is a system | |
69 | service that is pulled in by <filename>halt.target</filename> and | |
70 | is responsible for the actual system halt. Similarly, | |
71 | <filename>systemd-poweroff.service</filename> is pulled in by | |
72 | <filename>poweroff.target</filename>, | |
73 | <filename>systemd-reboot.service</filename> by | |
74 | <filename>reboot.target</filename> and | |
75 | <filename>systemd-kexec.service</filename> by | |
76 | <filename>kexec.target</filename> to execute the respective | |
77 | actions.</para> | |
78 | ||
79 | <para>When these services are run, they ensure that PID 1 is | |
80 | replaced by the | |
12b42c76 | 81 | <filename>/usr/lib/systemd/systemd-shutdown</filename> tool which |
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82 | is then responsible for the actual shutdown. Before shutting down, |
83 | this binary will try to unmount all remaining file systems, | |
84 | disable all remaining swap devices, detach all remaining storage | |
85 | devices and kill all remaining processes.</para> | |
86 | ||
87 | <para>It is necessary to have this code in a separate binary | |
88 | because otherwise rebooting after an upgrade might be broken — the | |
89 | running PID 1 could still depend on libraries which are not | |
90 | available any more, thus keeping the file system busy, which then | |
91 | cannot be re-mounted read-only.</para> | |
92 | ||
93 | <para>Immediately before executing the actual system | |
94 | halt/poweroff/reboot/kexec <filename>systemd-shutdown</filename> | |
95 | will run all executables in | |
12b42c76 | 96 | <filename>/usr/lib/systemd/system-shutdown/</filename> and pass |
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97 | one arguments to them: either <literal>halt</literal>, |
98 | <literal>poweroff</literal>, <literal>reboot</literal> or | |
99 | <literal>kexec</literal>, depending on the chosen action. All | |
100 | executables in this directory are executed in parallel, and | |
101 | execution of the action is not continued before all executables | |
102 | finished.</para> | |
103 | ||
104 | <para>Note that <filename>systemd-halt.service</filename> (and the | |
105 | related units) should never be executed directly. Instead, trigger | |
106 | system shutdown with a command such as <literal>systemctl | |
107 | halt</literal> or suchlike.</para> | |
108 | </refsect1> | |
109 | ||
110 | <refsect1> | |
111 | <title>See Also</title> | |
112 | <para> | |
113 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
114 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
115 | <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
116 | <citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry>, | |
117 | <citerefentry><refentrytitle>systemd-suspend.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
118 | </para> | |
119 | </refsect1> | |
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120 | |
121 | </refentry> |