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1 | <?xml version='1.0'?> <!--*-nxml-*--> |
2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | |
3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
4 | ||
5 | <!-- | |
6 | This file is part of systemd. | |
7 | ||
8 | Copyright 2012 Lennart Poettering | |
9 | ||
10 | systemd is free software; you can redistribute it and/or modify it | |
11 | under the terms of the GNU Lesser General Public License as published by | |
12 | the Free Software Foundation; either version 2.1 of the License, or | |
13 | (at your option) any later version. | |
14 | ||
15 | systemd is distributed in the hope that it will be useful, but | |
16 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
18 | Lesser General Public License for more details. | |
19 | ||
20 | You should have received a copy of the GNU Lesser General Public License | |
21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
22 | --> | |
23 | ||
24 | <refentry id="systemd-halt.service"> | |
25 | ||
26 | <refentryinfo> | |
27 | <title>systemd-halt.service</title> | |
28 | <productname>systemd</productname> | |
29 | ||
30 | <authorgroup> | |
31 | <author> | |
32 | <contrib>Developer</contrib> | |
33 | <firstname>Lennart</firstname> | |
34 | <surname>Poettering</surname> | |
35 | <email>lennart@poettering.net</email> | |
36 | </author> | |
37 | </authorgroup> | |
38 | </refentryinfo> | |
39 | ||
40 | <refmeta> | |
41 | <refentrytitle>systemd-halt.service</refentrytitle> | |
42 | <manvolnum>8</manvolnum> | |
43 | </refmeta> | |
44 | ||
45 | <refnamediv> | |
46 | <refname>systemd-halt.service</refname> | |
47 | <refname>systemd-poweroff.service</refname> | |
48 | <refname>systemd-reboot.service</refname> | |
49 | <refname>systemd-kexec.service</refname> | |
50 | <refname>systemd-shutdown</refname> | |
34511ca7 | 51 | <refpurpose>System shutdown logic</refpurpose> |
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52 | </refnamediv> |
53 | ||
54 | <refsynopsisdiv> | |
55 | <para><filename>systemd-halt.service</filename></para> | |
56 | <para><filename>systemd-poweroff.service</filename></para> | |
57 | <para><filename>systemd-reboot.service</filename></para> | |
58 | <para><filename>systemd-kexec.service</filename></para> | |
59 | <para><filename>/usr/lib/systemd/systemd-shutdown</filename></para> | |
60 | </refsynopsisdiv> | |
61 | ||
62 | <refsect1> | |
63 | <title>Description</title> | |
64 | ||
65 | <para><filename>systemd-halt.service</filename> is a | |
66 | system service that is pulled in by | |
67 | <filename>halt.target</filename> and is responsible | |
494a6682 | 68 | for the actual system halt. Similarly, |
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69 | <filename>systemd-poweroff.service</filename> is |
70 | pulled in by <filename>poweroff.target</filename>, | |
71 | <filename>systemd-reboot.service</filename> by | |
72 | <filename>reboot.target</filename> and | |
73 | <filename>systemd-kexec.service</filename> by | |
74 | <filename>kexec.target</filename> to execute the | |
75 | respective actions.</para> | |
76 | ||
63ba209d | 77 | <para>When these services are run, they ensure that PID |
0127336c | 78 | 1 is replaced by the |
8bd3b862 | 79 | <filename>/usr/lib/systemd/systemd-shutdown</filename> |
0127336c | 80 | tool which is then responsible for the actual |
63ba209d | 81 | shutdown. Before shutting down, this binary will try to |
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82 | unmount all remaining file systems, disable all |
83 | remaining swap devices, detach all remaining storage | |
84 | devices and kill all remaining processes.</para> | |
85 | ||
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86 | <para>It is necessary to have this code in a separate binary |
87 | because otherwise rebooting after an upgrade might be broken — | |
88 | the running PID 1 could still depend on libraries which are not | |
72ebbf34 | 89 | available any more, thus keeping the file system busy, which |
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90 | then cannot be re-mounted read-only.</para> |
91 | ||
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92 | <para>Immediately before executing the actual system |
93 | halt/poweroff/reboot/kexec | |
bb31a4ac | 94 | <filename>systemd-shutdown</filename> will run all |
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95 | executables in |
96 | <filename>/usr/lib/systemd/system-shutdown/</filename> | |
97 | and pass one arguments to them: either | |
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98 | <literal>halt</literal>, |
99 | <literal>poweroff</literal>, | |
100 | <literal>reboot</literal> or | |
101 | <literal>kexec</literal>, depending on the chosen | |
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102 | action. All executables in this directory are executed |
103 | in parallel, and execution of the action is not | |
104 | continued before all executables finished.</para> | |
105 | ||
106 | <para>Note that | |
107 | <filename>systemd-halt.service</filename> (and the | |
108 | related units) should never be executed | |
109 | directly. Instead, trigger system shutdown with a | |
909f413d | 110 | command such as <literal>systemctl halt</literal> or |
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111 | suchlike.</para> |
112 | </refsect1> | |
113 | ||
114 | <refsect1> | |
115 | <title>See Also</title> | |
116 | <para> | |
117 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
118 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
119 | <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
120 | <citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry>, | |
121 | <citerefentry><refentrytitle>systemd-suspend.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
122 | </para> | |
123 | </refsect1> | |
124 | ||
125 | </refentry> |