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1 | <?xml version="1.0"?> |
2 | <!--*-nxml-*--> | |
3 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
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 | ||
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> | |
49 | <para><filename>/etc/systemd/system-preset/*.preset</filename></para> | |
50 | <para><filename>/run/systemd/system-preset/*.preset</filename></para> | |
51 | <para><filename>/usr/lib/systemd/system-preset/*.preset</filename></para> | |
52 | <para><filename>/etc/systemd/user-preset/*.preset</filename></para> | |
53 | <para><filename>/run/systemd/user-preset/*.preset</filename></para> | |
54 | <para><filename>/usr/lib/systemd/user-preset/*.preset</filename></para> | |
55 | </refsynopsisdiv> | |
56 | ||
57 | <refsect1> | |
58 | <title>Description</title> | |
59 | ||
60 | <para>Preset files may be used to encode policy which | |
305f376c | 61 | units shall be enabled by default and which ones |
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62 | shall be disabled. They are read by <command>systemctl |
63 | preset</command> (for more information see | |
64 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>) | |
65 | which uses this information to enable or disable a | |
66 | unit according to preset policy. <command>systemctl | |
67 | preset</command> is used by the post install | |
68 | scriptlets of RPM packages (or other OS package formats), | |
69 | to enable/disable specific units by default on package | |
70 | installation, enforcing distribution, spin or | |
71 | administrator preset policy. This allows choosing a certain | |
72 | set of units to be enabled/disabled even before | |
73 | installing the actual package.</para> | |
74 | ||
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75 | <para>For more information on the preset logic please |
76 | have a look at the <ulink | |
77 | url="http://freedesktop.org/wiki/Software/systemd/Preset">Presets</ulink> | |
78 | document.</para> | |
79 | ||
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80 | <para>It is not recommended to ship preset files |
81 | within the respective software packages implementing | |
305f376c | 82 | the units, but rather centralize them in a |
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83 | distribution or spin default policy, which can be |
84 | amended by administrator policy.</para> | |
85 | ||
86 | <para>If no preset files exist, <command>systemctl | |
87 | preset</command> will enable all units that are | |
88 | installed by default. If this is not desired and all | |
89 | units shall rather be disabled it is necessary to ship | |
90 | a preset file with a single, catchall | |
91 | "<filename>disable *</filename>" line. (See example 1, | |
92 | below.)</para> | |
93 | </refsect1> | |
94 | ||
95 | <refsect1> | |
96 | <title>Preset File Format</title> | |
97 | ||
98 | <para>The preset files contain a list of | |
99 | directives consisting of either the word | |
100 | <literal>enable</literal> or | |
101 | <literal>disable</literal> followed by a space and a | |
102 | unit name (possibly with shell style wildcards), | |
103 | separated by newlines. Empty lines and lines whose | |
104 | first non-whitespace character is # or ; are | |
105 | ignored.</para> | |
106 | ||
107 | <para>Two different directives are understood: | |
108 | <literal>enable</literal> may be used to enable units | |
109 | by default, <literal>disable</literal> to disable | |
110 | units by default.</para> | |
111 | ||
112 | <para>If multiple lines apply to a unit name the | |
113 | first matching one takes precedence over all | |
114 | others.</para> | |
115 | ||
116 | <para>Each preset file shall be named in the style of | |
117 | <filename><priority>-<program>.conf</filename>. | |
118 | Files in <filename>/etc/</filename> override files | |
119 | with the same name in <filename>/usr/lib/</filename> | |
120 | and <filename>/run/</filename>. Files in | |
121 | <filename>/run/</filename> override files with the | |
122 | same name in <filename>/usr/lib/</filename>. Packages | |
123 | should install their preset files in | |
124 | <filename>/usr/lib/</filename>. Files in | |
125 | <filename>/etc/</filename> are reserved for the local | |
126 | administrator, who may use this logic to override the | |
127 | preset files installed by vendor packages. All preset | |
128 | files are sorted by their filename in alphabetical | |
129 | order, regardless in which of the directories they | |
130 | reside, to guarantee that a specific preset file takes | |
131 | precedence over another file with an alphabetically | |
132 | earlier name, if both files contain lines that apply | |
133 | to the same unit names. It is recommended to prefix | |
134 | all file names with two-digit number, to simplify | |
135 | ordering.</para> | |
136 | ||
137 | <para>If the administrator wants to disable a preset | |
138 | file supplied by the vendor the recommended way is to | |
139 | place a symlink to <filename>/dev/null</filename> in | |
140 | <filename>/etc/systemd/system-preset/</filename> | |
141 | bearing the same file name.</para> | |
142 | </refsect1> | |
143 | ||
144 | <refsect1> | |
145 | <title>Example</title> | |
146 | ||
147 | <example> | |
148 | <title>Default off example <filename>/usr/lib/systemd/system-preset/99-default.preset</filename>:</title> | |
149 | ||
150 | <programlisting>disable *</programlisting> | |
151 | </example> | |
152 | ||
153 | <para>This disables all units. Due to the file name | |
154 | prefix <literal>99-</literal> it will be read last and | |
155 | hence can easily be overridden by spin or | |
156 | administrator preset policy or suchlike.</para> | |
157 | ||
158 | <example> | |
159 | <title>A GNOME spin example <filename>/usr/lib/systemd/system-preset/50-gnome.preset</filename>:</title> | |
160 | ||
161 | <programlisting>enable gdm.service | |
162 | enable colord.service | |
163 | enable accounts-daemon.service | |
164 | enable avahi-daemon.*</programlisting> | |
165 | ||
166 | </example> | |
167 | ||
168 | <para>This enables the three mentioned units, plus all | |
169 | <filename>avahi-daemon</filename> regardless of which | |
170 | unit type. A file like this could be useful for | |
171 | inclusion in a GNOME spin of a distribution. It will | |
172 | ensure that the units necessary for GNOME are properly | |
173 | enabled as they are installed. It leaves all other | |
174 | units untouched, and subject to other (later) preset | |
175 | files, for example like the one from the first example | |
176 | above.</para> | |
177 | ||
178 | <example> | |
179 | <title>Administrator policy <filename>/etc/systemd/system-preset/00-lennart.preset</filename>:</title> | |
180 | ||
181 | <programlisting>enable httpd.service | |
182 | enable sshd.service | |
183 | enable postfix.service | |
184 | disable *</programlisting> | |
185 | </example> | |
186 | ||
187 | <para>This enables three specific services and | |
188 | disables all others. This is useful for administrators | |
189 | to specifically select the units to enable, and | |
190 | disable all others. Due to the file name prefix | |
191 | <literal>00-</literal> it will be read early and hence | |
192 | overrides all other preset policy files.</para> | |
193 | </refsect1> | |
194 | ||
195 | <refsect1> | |
196 | <title>See Also</title> | |
197 | <para> | |
198 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
199 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
200 | <citerefentry><refentrytitle>systemd-delta</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
201 | </para> | |
202 | </refsect1> | |
203 | ||
204 | </refentry> |