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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 | <!ENTITY % entities SYSTEM "custom-entities.ent" > | |
5 | %entities; | |
6 | ]> | |
7 | ||
8 | <!-- | |
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9 | SPDX-License-Identifier: LGPL-2.1+ |
10 | ||
96b2fb93 | 11 | Copyright © 2017 Zbigniew Jędrzejewski-Szmek |
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12 | --> |
13 | ||
232bd677 | 14 | <refentry id="systemd.environment-generator" conditional='ENABLE_ENVIRONMENT_D' |
15 | xmlns:xi="http://www.w3.org/2001/XInclude"> | |
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16 | <refentryinfo> |
17 | <title>systemd.environment-generator</title> | |
18 | <productname>systemd</productname> | |
19 | ||
20 | <authorgroup> | |
21 | <author> | |
22 | <contrib>Developer</contrib> | |
23 | <firstname>Zbigniew</firstname> | |
24 | <surname>Jędrzejewski-Szmek</surname> | |
25 | <email>zbyszek@in.waw.pl</email> | |
26 | </author> | |
27 | </authorgroup> | |
28 | </refentryinfo> | |
29 | ||
30 | <refmeta> | |
31 | <refentrytitle>systemd.environment-generator</refentrytitle> | |
32 | <manvolnum>7</manvolnum> | |
33 | </refmeta> | |
34 | ||
35 | <refnamediv> | |
36 | <refname>systemd.environment-generator</refname> | |
f95b0be7 | 37 | <refpurpose>systemd environment file generators</refpurpose> |
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38 | </refnamediv> |
39 | ||
40 | <refsynopsisdiv> | |
41 | <cmdsynopsis> | |
42 | <command>&systemenvgeneratordir;/some-generator</command> | |
43 | </cmdsynopsis> | |
44 | <cmdsynopsis> | |
45 | <command>&userenvgeneratordir;/some-generator</command> | |
46 | </cmdsynopsis> | |
47 | ||
48 | <para> | |
49 | <literallayout><filename>/run/systemd/system-environment-generators/*</filename> | |
50 | <filename>/etc/systemd/system-environment-generators/*</filename> | |
51 | <filename>/usr/local/lib/systemd/system-environment-generators/*</filename> | |
52 | <filename>&systemenvgeneratordir;/*</filename></literallayout> | |
53 | </para> | |
54 | ||
55 | <para> | |
56 | <literallayout><filename>/run/systemd/user-environment-generators/*</filename> | |
57 | <filename>/etc/systemd/user-environment-generators/*</filename> | |
58 | <filename>/usr/local/lib/systemd/user-environment-generators/*</filename> | |
59 | <filename>&userenvgeneratordir;/*</filename></literallayout> | |
60 | </para> | |
61 | </refsynopsisdiv> | |
62 | ||
63 | <refsect1> | |
64 | <title>Description</title> | |
65 | <para>Generators are small executables that live in | |
66 | <filename>&systemenvgeneratordir;/</filename> and other directories listed above. | |
67 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry> will | |
68 | execute those binaries very early at the startup of each manager and at configuration | |
69 | reload time, before running the generators described in | |
70 | <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
71 | and before starting any units. Environment generators can override the environment that the | |
72 | manager exports to services and other processes.</para> | |
73 | ||
74 | <para>Generators are loaded from a set of paths determined during compilation, as listed | |
75 | above. System and user environment generators are loaded from directories with names ending in | |
76 | <filename>system-environment-generators/</filename> and | |
77 | <filename>user-environment-generators/</filename>, respectively. Generators found in directories | |
78 | listed earlier override the ones with the same name in directories lower in the list. A symlink | |
79 | to <filename>/dev/null</filename> or an empty file can be used to mask a generator, thereby | |
80 | preventing it from running. Please note that the order of the two directories with the highest | |
81 | priority is reversed with respect to the unit load path, and generators in | |
82 | <filename>/run</filename> overwrite those in <filename>/etc</filename>.</para> | |
83 | ||
84 | <para>After installing new generators or updating the configuration, <command>systemctl | |
85 | daemon-reload</command> may be executed. This will re-run all generators, updating environment | |
86 | configuration. It will be used for any services that are started subsequently.</para> | |
87 | ||
88 | <para>Environment file generators are executed similarly to unit file generators described | |
89 | in | |
90 | <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
91 | with the following differences:</para> | |
92 | ||
93 | <itemizedlist> | |
94 | <listitem> | |
95 | <para>Generators are executed sequentially in the alphanumerical order of the final | |
96 | component of their name. The output of each generator output is immediately parsed and used | |
97 | to update the environment for generators that run after that. Thus, later generators can use | |
98 | and/or modify the output of earlier generators.</para> | |
99 | </listitem> | |
100 | ||
101 | <listitem> | |
102 | <para>Generators are run by every manager instance, their output can be different for each | |
103 | user.</para> | |
104 | </listitem> | |
105 | </itemizedlist> | |
106 | ||
107 | <para>It is recommended to use numerical prefixes for generator names to simplify ordering.</para> | |
108 | </refsect1> | |
109 | ||
110 | <refsect1> | |
111 | <title>Examples</title> | |
112 | ||
113 | <example> | |
114 | <title>A simple generator that extends an environment variable if a directory exists in the file system</title> | |
115 | ||
116 | <programlisting># 50-xdg-data-dirs.sh | |
117 | ||
118 | <xi:include href="50-xdg-data-dirs.sh" parse="text" /></programlisting> | |
119 | </example> | |
120 | ||
121 | <example> | |
122 | <title>A more complicated generator which reads existing configuration and mutates one variable</title> | |
123 | ||
124 | <programlisting># 90-rearrange-path.py | |
125 | ||
126 | <xi:include href="90-rearrange-path.py" parse="text" /></programlisting> | |
127 | </example> | |
128 | ||
129 | <example> | |
130 | <title>Debugging a generator</title> | |
131 | ||
132 | <programlisting>SYSTEMD_LOG_LEVEL=debug VAR_A=something VAR_B="something else" \ | |
133 | &systemenvgeneratordir;/path-to-generator | |
134 | </programlisting> | |
135 | </example> | |
136 | </refsect1> | |
137 | ||
138 | <refsect1> | |
139 | <title>See also</title> | |
140 | ||
141 | <para> | |
f63c4aab | 142 | <citerefentry><refentrytitle>systemd-environment-d-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
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143 | <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>, |
144 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
145 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
146 | </para> | |
147 | </refsect1> | |
148 | </refentry> |