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2897b343 | 1 | <?xml version='1.0'?> <!--*-nxml-*--> |
bb4f798a | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
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3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [ |
4 | <!ENTITY % entities SYSTEM "custom-entities.ent" > | |
5 | %entities; | |
6 | ]> | |
a032b68d | 7 | <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> |
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81c58355 MB |
9 | <refentry id="systemd.environment-generator" conditional='ENABLE_ENVIRONMENT_D' |
10 | xmlns:xi="http://www.w3.org/2001/XInclude"> | |
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11 | <refentryinfo> |
12 | <title>systemd.environment-generator</title> | |
13 | <productname>systemd</productname> | |
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14 | </refentryinfo> |
15 | ||
16 | <refmeta> | |
17 | <refentrytitle>systemd.environment-generator</refentrytitle> | |
18 | <manvolnum>7</manvolnum> | |
19 | </refmeta> | |
20 | ||
21 | <refnamediv> | |
22 | <refname>systemd.environment-generator</refname> | |
52ad194e | 23 | <refpurpose>systemd environment file generators</refpurpose> |
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24 | </refnamediv> |
25 | ||
26 | <refsynopsisdiv> | |
27 | <cmdsynopsis> | |
8b3d4ff0 | 28 | <command>&SYSTEM_ENV_GENERATOR_DIR;/some-generator</command> |
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29 | </cmdsynopsis> |
30 | <cmdsynopsis> | |
8b3d4ff0 | 31 | <command>&USER_ENV_GENERATOR_DIR;/some-generator</command> |
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32 | </cmdsynopsis> |
33 | ||
34 | <para> | |
35 | <literallayout><filename>/run/systemd/system-environment-generators/*</filename> | |
36 | <filename>/etc/systemd/system-environment-generators/*</filename> | |
37 | <filename>/usr/local/lib/systemd/system-environment-generators/*</filename> | |
8b3d4ff0 | 38 | <filename>&SYSTEM_ENV_GENERATOR_DIR;/*</filename></literallayout> |
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39 | </para> |
40 | ||
41 | <para> | |
42 | <literallayout><filename>/run/systemd/user-environment-generators/*</filename> | |
43 | <filename>/etc/systemd/user-environment-generators/*</filename> | |
44 | <filename>/usr/local/lib/systemd/user-environment-generators/*</filename> | |
8b3d4ff0 | 45 | <filename>&USER_ENV_GENERATOR_DIR;/*</filename></literallayout> |
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46 | </para> |
47 | </refsynopsisdiv> | |
48 | ||
49 | <refsect1> | |
50 | <title>Description</title> | |
51 | <para>Generators are small executables that live in | |
8b3d4ff0 | 52 | <filename>&SYSTEM_ENV_GENERATOR_DIR;/</filename> and other directories listed above. |
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53 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry> will |
54 | execute those binaries very early at the startup of each manager and at configuration | |
55 | reload time, before running the generators described in | |
56 | <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
57 | and before starting any units. Environment generators can override the environment that the | |
58 | manager exports to services and other processes.</para> | |
59 | ||
60 | <para>Generators are loaded from a set of paths determined during compilation, as listed | |
61 | above. System and user environment generators are loaded from directories with names ending in | |
62 | <filename>system-environment-generators/</filename> and | |
63 | <filename>user-environment-generators/</filename>, respectively. Generators found in directories | |
64 | listed earlier override the ones with the same name in directories lower in the list. A symlink | |
65 | to <filename>/dev/null</filename> or an empty file can be used to mask a generator, thereby | |
66 | preventing it from running. Please note that the order of the two directories with the highest | |
67 | priority is reversed with respect to the unit load path, and generators in | |
a032b68d | 68 | <filename>/run/</filename> overwrite those in <filename>/etc/</filename>.</para> |
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69 | |
70 | <para>After installing new generators or updating the configuration, <command>systemctl | |
71 | daemon-reload</command> may be executed. This will re-run all generators, updating environment | |
72 | configuration. It will be used for any services that are started subsequently.</para> | |
73 | ||
74 | <para>Environment file generators are executed similarly to unit file generators described | |
75 | in | |
76 | <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
77 | with the following differences:</para> | |
78 | ||
79 | <itemizedlist> | |
80 | <listitem> | |
81 | <para>Generators are executed sequentially in the alphanumerical order of the final | |
82 | component of their name. The output of each generator output is immediately parsed and used | |
83 | to update the environment for generators that run after that. Thus, later generators can use | |
84 | and/or modify the output of earlier generators.</para> | |
85 | </listitem> | |
86 | ||
87 | <listitem> | |
88 | <para>Generators are run by every manager instance, their output can be different for each | |
89 | user.</para> | |
90 | </listitem> | |
91 | </itemizedlist> | |
92 | ||
93 | <para>It is recommended to use numerical prefixes for generator names to simplify ordering.</para> | |
94 | </refsect1> | |
95 | ||
96 | <refsect1> | |
97 | <title>Examples</title> | |
98 | ||
99 | <example> | |
100 | <title>A simple generator that extends an environment variable if a directory exists in the file system</title> | |
101 | ||
102 | <programlisting># 50-xdg-data-dirs.sh | |
103 | ||
104 | <xi:include href="50-xdg-data-dirs.sh" parse="text" /></programlisting> | |
105 | </example> | |
106 | ||
107 | <example> | |
108 | <title>A more complicated generator which reads existing configuration and mutates one variable</title> | |
109 | ||
110 | <programlisting># 90-rearrange-path.py | |
111 | ||
112 | <xi:include href="90-rearrange-path.py" parse="text" /></programlisting> | |
113 | </example> | |
114 | ||
115 | <example> | |
116 | <title>Debugging a generator</title> | |
117 | ||
118 | <programlisting>SYSTEMD_LOG_LEVEL=debug VAR_A=something VAR_B="something else" \ | |
8b3d4ff0 | 119 | &SYSTEM_ENV_GENERATOR_DIR;/path-to-generator |
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120 | </programlisting> |
121 | </example> | |
122 | </refsect1> | |
123 | ||
124 | <refsect1> | |
125 | <title>See also</title> | |
126 | ||
127 | <para> | |
128 | <citerefentry><refentrytitle>systemd-environment-d-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, | |
129 | <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
130 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
131 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
132 | </para> | |
133 | </refsect1> | |
134 | </refentry> |