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logind: send dbus signals when sessions/users/seats come and go
[elogind.git] / man / systemd.target.xml
1 <?xml version='1.0'?> <!--*-nxml-*-->
2 <?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"?>
3 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
4         "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
5
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9   Copyright 2010 Lennart Poettering
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24
25 <refentry id="systemd.target">
26         <refentryinfo>
27                 <title>systemd.target</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.target</refentrytitle>
42                 <manvolnum>5</manvolnum>
43         </refmeta>
44
45         <refnamediv>
46                 <refname>systemd.target</refname>
47                 <refpurpose>systemd target configuration files</refpurpose>
48         </refnamediv>
49
50         <refsynopsisdiv>
51                 <para><filename>systemd.target</filename></para>
52         </refsynopsisdiv>
53
54         <refsect1>
55                 <title>Description</title>
56
57                 <para>A unit configuration file whose name ends in
58                 <filename>.target</filename> encodes information about
59                 a target unit of systemd, which is used for grouping
60                 units and as well-known synchronization points during
61                 start-up.</para>
62
63                 <para>This unit type has no specific options. See
64                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
65                 for the common options of all unit configuration
66                 files. The common configuration items are configured
67                 in the generic [Unit] and [Install] sections. A
68                 separate [Target] section does not exist, since no
69                 target-specific options may be configured.</para>
70
71                 <para>Target units do not offer any additional
72                 functionality on top of the generic functionality
73                 provided by units. They exist merely to group units via dependencies
74                 (useful as boot targets), and to establish
75                 standardized names for synchronization points used in
76                 dependencies between units. Among other things, target
77                 units are a more flexible replacement for SysV
78                 runlevels in the classic SysV init system. (And for
79                 compatibility reasons special
80                 target units such as
81                 <filename>runlevel3.target</filename> exist which are used by
82                 the SysV runlevel compatibility code in systemd. See
83                 <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>
84                 for details).</para>
85
86                 <para>Unless <varname>DefaultDependencies=</varname>
87                 is set to <option>false</option>, target units will
88                 implicitly complement all configured dependencies of
89                 type <varname>Wants=</varname>,
90                 <varname>Requires=</varname>,
91                 <varname>RequiresOverridable=</varname> with
92                 dependencies of type <varname>After=</varname> if the
93                 units in question also have
94                 <varname>DefaultDependencies=true</varname>.
95                 </para>
96         </refsect1>
97
98         <refsect1>
99                   <title>See Also</title>
100                   <para>
101                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
102                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
103                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
104                           <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>
105                   </para>
106         </refsect1>
107
108 </refentry>