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1 | <?xml version="1.0"?> |
2 | <!--*-nxml-*--> | |
12b42c76 | 3 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
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4 | <!-- |
5 | This file is part of systemd. | |
6 | ||
7 | Copyright 2011 Lennart Poettering | |
8 | ||
9 | systemd is free software; you can redistribute it and/or modify it | |
10 | under the terms of the GNU Lesser General Public License as published by | |
11 | the Free Software Foundation; either version 2.1 of the License, or | |
12 | (at your option) any later version. | |
13 | ||
14 | systemd is distributed in the hope that it will be useful, but | |
15 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
17 | Lesser General Public License for more details. | |
18 | ||
19 | You should have received a copy of the GNU Lesser General Public License | |
20 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
21 | --> | |
22 | <refentry id="systemd.preset"> | |
23 | ||
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24 | <refentryinfo> |
25 | <title>systemd.preset</title> | |
26 | <productname>systemd</productname> | |
27 | ||
28 | <authorgroup> | |
29 | <author> | |
30 | <contrib>Developer</contrib> | |
31 | <firstname>Lennart</firstname> | |
32 | <surname>Poettering</surname> | |
33 | <email>lennart@poettering.net</email> | |
34 | </author> | |
35 | </authorgroup> | |
36 | </refentryinfo> | |
37 | ||
38 | <refmeta> | |
39 | <refentrytitle>systemd.preset</refentrytitle> | |
40 | <manvolnum>5</manvolnum> | |
41 | </refmeta> | |
42 | ||
43 | <refnamediv> | |
44 | <refname>systemd.preset</refname> | |
45 | <refpurpose>Service enablement presets</refpurpose> | |
46 | </refnamediv> | |
47 | ||
48 | <refsynopsisdiv> | |
12b42c76 | 49 | <para><filename>/etc/systemd/system-preset/*.preset</filename></para> |
798d3a52 | 50 | <para><filename>/run/systemd/system-preset/*.preset</filename></para> |
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51 | <para><filename>/usr/lib/systemd/system-preset/*.preset</filename></para> |
52 | <para><filename>/etc/systemd/user-preset/*.preset</filename></para> | |
798d3a52 | 53 | <para><filename>/run/systemd/user-preset/*.preset</filename></para> |
12b42c76 | 54 | <para><filename>/usr/lib/systemd/user-preset/*.preset</filename></para> |
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55 | </refsynopsisdiv> |
56 | ||
57 | <refsect1> | |
58 | <title>Description</title> | |
59 | ||
60 | <para>Preset files may be used to encode policy which units shall | |
61 | be enabled by default and which ones shall be disabled. They are | |
62 | read by <command>systemctl preset</command> (for more information | |
63 | see | |
64 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>) | |
65 | which uses this information to enable or disable a unit according | |
66 | to preset policy. <command>systemctl preset</command> is used by | |
67 | the post install scriptlets of RPM packages (or other OS package | |
68 | formats), to enable/disable specific units by default on package | |
69 | installation, enforcing distribution, spin or administrator preset | |
70 | policy. This allows choosing a certain set of units to be | |
71 | enabled/disabled even before installing the actual package.</para> | |
72 | ||
73 | <para>For more information on the preset logic please have a look | |
74 | at the <ulink | |
75 | url="http://freedesktop.org/wiki/Software/systemd/Preset">Presets</ulink> | |
76 | document.</para> | |
77 | ||
78 | <para>It is not recommended to ship preset files within the | |
79 | respective software packages implementing the units, but rather | |
80 | centralize them in a distribution or spin default policy, which | |
81 | can be amended by administrator policy.</para> | |
82 | ||
83 | <para>If no preset files exist, <command>systemctl | |
84 | preset</command> will enable all units that are installed by | |
85 | default. If this is not desired and all units shall rather be | |
86 | disabled, it is necessary to ship a preset file with a single, | |
87 | catchall "<filename>disable *</filename>" line. (See example 1, | |
88 | below.)</para> | |
89 | </refsect1> | |
90 | ||
91 | <refsect1> | |
92 | <title>Preset File Format</title> | |
93 | ||
94 | <para>The preset files contain a list of directives consisting of | |
95 | either the word <literal>enable</literal> or | |
96 | <literal>disable</literal> followed by a space and a unit name | |
97 | (possibly with shell style wildcards), separated by newlines. | |
98 | Empty lines and lines whose first non-whitespace character is # or | |
99 | ; are ignored.</para> | |
100 | ||
101 | <para>Two different directives are understood: | |
102 | <literal>enable</literal> may be used to enable units by default, | |
103 | <literal>disable</literal> to disable units by default.</para> | |
104 | ||
105 | <para>If multiple lines apply to a unit name, the first matching | |
106 | one takes precedence over all others.</para> | |
107 | ||
108 | <para>Each preset file shall be named in the style of | |
9e0d90f9 | 109 | <filename><priority>-<policy-name>.preset</filename>. Files |
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110 | in <filename>/etc/</filename> override files with the same name in |
111 | <filename>/usr/lib/</filename> and <filename>/run/</filename>. | |
112 | Files in <filename>/run/</filename> override files with the same | |
113 | name in <filename>/usr/lib/</filename>. Packages should install | |
114 | their preset files in <filename>/usr/lib/</filename>. Files in | |
115 | <filename>/etc/</filename> are reserved for the local | |
116 | administrator, who may use this logic to override the preset files | |
117 | installed by vendor packages. All preset files are sorted by their | |
118 | filename in lexicographic order, regardless of which of the | |
119 | directories they reside in. If multiple files specify the same | |
120 | unit name, the entry in the file with the lexicographically | |
121 | earliest name will be applied. It is recommended to prefix all | |
122 | filenames with a two-digit number and a dash, to simplify the | |
123 | ordering of the files.</para> | |
124 | ||
125 | <para>If the administrator wants to disable a preset file supplied | |
126 | by the vendor, the recommended way is to place a symlink to | |
127 | <filename>/dev/null</filename> in | |
12b42c76 | 128 | <filename>/etc/systemd/system-preset/</filename> bearing the same |
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129 | filename.</para> |
130 | </refsect1> | |
131 | ||
132 | <refsect1> | |
133 | <title>Example</title> | |
134 | ||
135 | <example> | |
12b42c76 | 136 | <title>Default off example <filename>/usr/lib/systemd/system-preset/99-default.preset</filename>:</title> |
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137 | |
138 | <programlisting>disable *</programlisting> | |
139 | </example> | |
140 | ||
141 | <para>This disables all units. Due to the filename prefix | |
142 | <literal>99-</literal>, it will be read last and hence can easily | |
143 | be overridden by spin or administrator preset policy or | |
144 | suchlike.</para> | |
145 | ||
146 | <example> | |
12b42c76 | 147 | <title>A GNOME spin example <filename>/usr/lib/systemd/system-preset/50-gnome.preset</filename>:</title> |
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148 | |
149 | <programlisting>enable gdm.service | |
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150 | enable colord.service |
151 | enable accounts-daemon.service | |
152 | enable avahi-daemon.*</programlisting> | |
153 | ||
798d3a52 | 154 | </example> |
75d67e68 | 155 | |
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156 | <para>This enables the three mentioned units, plus all |
157 | <filename>avahi-daemon</filename> regardless of which unit type. A | |
158 | file like this could be useful for inclusion in a GNOME spin of a | |
159 | distribution. It will ensure that the units necessary for GNOME | |
160 | are properly enabled as they are installed. It leaves all other | |
161 | units untouched, and subject to other (later) preset files, for | |
162 | example like the one from the first example above.</para> | |
75d67e68 | 163 | |
798d3a52 | 164 | <example> |
12b42c76 | 165 | <title>Administrator policy <filename>/etc/systemd/system-preset/00-lennart.preset</filename>:</title> |
75d67e68 | 166 | |
798d3a52 | 167 | <programlisting>enable httpd.service |
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168 | enable sshd.service |
169 | enable postfix.service | |
170 | disable *</programlisting> | |
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171 | </example> |
172 | ||
173 | <para>This enables three specific services and disables all | |
174 | others. This is useful for administrators to specifically select | |
175 | the units to enable, and disable all others. Due to the filename | |
176 | prefix <literal>00-</literal> it will be read early and hence | |
177 | overrides all other preset policy files.</para> | |
178 | </refsect1> | |
179 | ||
180 | <refsect1> | |
181 | <title>See Also</title> | |
182 | <para> | |
183 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
184 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
185 | <citerefentry><refentrytitle>systemd-delta</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
186 | </para> | |
187 | </refsect1> | |
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188 | |
189 | </refentry> |