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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 | <!-- | |
572eb058 | 9 | SPDX-License-Identifier: LGPL-2.1+ |
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10 | --> |
11 | ||
232bd677 | 12 | <refentry id="systemd.environment-generator" conditional='ENABLE_ENVIRONMENT_D' |
13 | xmlns:xi="http://www.w3.org/2001/XInclude"> | |
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14 | <refentryinfo> |
15 | <title>systemd.environment-generator</title> | |
16 | <productname>systemd</productname> | |
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17 | </refentryinfo> |
18 | ||
19 | <refmeta> | |
20 | <refentrytitle>systemd.environment-generator</refentrytitle> | |
21 | <manvolnum>7</manvolnum> | |
22 | </refmeta> | |
23 | ||
24 | <refnamediv> | |
25 | <refname>systemd.environment-generator</refname> | |
f95b0be7 | 26 | <refpurpose>systemd environment file generators</refpurpose> |
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27 | </refnamediv> |
28 | ||
29 | <refsynopsisdiv> | |
30 | <cmdsynopsis> | |
31 | <command>&systemenvgeneratordir;/some-generator</command> | |
32 | </cmdsynopsis> | |
33 | <cmdsynopsis> | |
34 | <command>&userenvgeneratordir;/some-generator</command> | |
35 | </cmdsynopsis> | |
36 | ||
37 | <para> | |
38 | <literallayout><filename>/run/systemd/system-environment-generators/*</filename> | |
39 | <filename>/etc/systemd/system-environment-generators/*</filename> | |
40 | <filename>/usr/local/lib/systemd/system-environment-generators/*</filename> | |
41 | <filename>&systemenvgeneratordir;/*</filename></literallayout> | |
42 | </para> | |
43 | ||
44 | <para> | |
45 | <literallayout><filename>/run/systemd/user-environment-generators/*</filename> | |
46 | <filename>/etc/systemd/user-environment-generators/*</filename> | |
47 | <filename>/usr/local/lib/systemd/user-environment-generators/*</filename> | |
48 | <filename>&userenvgeneratordir;/*</filename></literallayout> | |
49 | </para> | |
50 | </refsynopsisdiv> | |
51 | ||
52 | <refsect1> | |
53 | <title>Description</title> | |
54 | <para>Generators are small executables that live in | |
55 | <filename>&systemenvgeneratordir;/</filename> and other directories listed above. | |
56 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry> will | |
57 | execute those binaries very early at the startup of each manager and at configuration | |
58 | reload time, before running the generators described in | |
59 | <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
60 | and before starting any units. Environment generators can override the environment that the | |
61 | manager exports to services and other processes.</para> | |
62 | ||
63 | <para>Generators are loaded from a set of paths determined during compilation, as listed | |
64 | above. System and user environment generators are loaded from directories with names ending in | |
65 | <filename>system-environment-generators/</filename> and | |
66 | <filename>user-environment-generators/</filename>, respectively. Generators found in directories | |
67 | listed earlier override the ones with the same name in directories lower in the list. A symlink | |
68 | to <filename>/dev/null</filename> or an empty file can be used to mask a generator, thereby | |
69 | preventing it from running. Please note that the order of the two directories with the highest | |
70 | priority is reversed with respect to the unit load path, and generators in | |
71 | <filename>/run</filename> overwrite those in <filename>/etc</filename>.</para> | |
72 | ||
73 | <para>After installing new generators or updating the configuration, <command>systemctl | |
74 | daemon-reload</command> may be executed. This will re-run all generators, updating environment | |
75 | configuration. It will be used for any services that are started subsequently.</para> | |
76 | ||
77 | <para>Environment file generators are executed similarly to unit file generators described | |
78 | in | |
79 | <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
80 | with the following differences:</para> | |
81 | ||
82 | <itemizedlist> | |
83 | <listitem> | |
84 | <para>Generators are executed sequentially in the alphanumerical order of the final | |
85 | component of their name. The output of each generator output is immediately parsed and used | |
86 | to update the environment for generators that run after that. Thus, later generators can use | |
87 | and/or modify the output of earlier generators.</para> | |
88 | </listitem> | |
89 | ||
90 | <listitem> | |
91 | <para>Generators are run by every manager instance, their output can be different for each | |
92 | user.</para> | |
93 | </listitem> | |
94 | </itemizedlist> | |
95 | ||
96 | <para>It is recommended to use numerical prefixes for generator names to simplify ordering.</para> | |
97 | </refsect1> | |
98 | ||
99 | <refsect1> | |
100 | <title>Examples</title> | |
101 | ||
102 | <example> | |
103 | <title>A simple generator that extends an environment variable if a directory exists in the file system</title> | |
104 | ||
105 | <programlisting># 50-xdg-data-dirs.sh | |
106 | ||
107 | <xi:include href="50-xdg-data-dirs.sh" parse="text" /></programlisting> | |
108 | </example> | |
109 | ||
110 | <example> | |
111 | <title>A more complicated generator which reads existing configuration and mutates one variable</title> | |
112 | ||
113 | <programlisting># 90-rearrange-path.py | |
114 | ||
115 | <xi:include href="90-rearrange-path.py" parse="text" /></programlisting> | |
116 | </example> | |
117 | ||
118 | <example> | |
119 | <title>Debugging a generator</title> | |
120 | ||
121 | <programlisting>SYSTEMD_LOG_LEVEL=debug VAR_A=something VAR_B="something else" \ | |
122 | &systemenvgeneratordir;/path-to-generator | |
123 | </programlisting> | |
124 | </example> | |
125 | </refsect1> | |
126 | ||
127 | <refsect1> | |
128 | <title>See also</title> | |
129 | ||
130 | <para> | |
f63c4aab | 131 | <citerefentry><refentrytitle>systemd-environment-d-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
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132 | <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>, |
133 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
134 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
135 | </para> | |
136 | </refsect1> | |
137 | </refentry> |