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1 | <?xml version="1.0"?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*--> |
2 | <!DOCTYPE refsection PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" | |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"> |
d3fae78f | 4 | |
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5 | <!-- |
6 | SPDX-License-Identifier: LGPL-2.1+ | |
7 | ||
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8 | Copyright 2015 Zbigniew Jędrzejewski-Szmek |
9 | Copyright 2014 Josh Triplett | |
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10 | --> |
11 | ||
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12 | <refsection> |
13 | <refsection id='confd'> | |
14 | <title>Configuration Directories and Precedence</title> | |
15 | ||
16 | <para>Configuration files are read from directories in | |
17 | <filename>/etc/</filename>, <filename>/run/</filename>, and | |
18 | <filename>/usr/lib/</filename>, in order of precedence. | |
19 | Each configuration file in these configuration directories shall be named in | |
20 | the style of <filename><replaceable>filename</replaceable>.conf</filename>. | |
21 | Files in <filename>/etc/</filename> override files with the same name in | |
22 | <filename>/run/</filename> and <filename>/usr/lib/</filename>. Files in | |
23 | <filename>/run/</filename> override files with the same name in | |
24 | <filename>/usr/lib/</filename>.</para> | |
25 | ||
26 | <para>Packages should install their configuration files in | |
27 | <filename>/usr/lib/</filename>. Files in <filename>/etc/</filename> are | |
28 | reserved for the local administrator, who may use this logic to override the | |
29 | configuration files installed by vendor packages. All configuration files | |
30 | are sorted by their filename in lexicographic order, regardless of which of | |
31 | the directories they reside in. If multiple files specify the same option, | |
32 | the entry in the file with the lexicographically latest name will take | |
33 | precedence. It is recommended to prefix all filenames with a two-digit number | |
34 | and a dash, to simplify the ordering of the files.</para> | |
35 | ||
36 | <para>If the administrator wants to disable a configuration file supplied by | |
37 | the vendor, the recommended way is to place a symlink to | |
38 | <filename>/dev/null</filename> in the configuration directory in | |
39 | <filename>/etc/</filename>, with the same filename as the vendor | |
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40 | configuration file. If the vendor configuration file is included in |
41 | the initrd image, the image has to be regenerated.</para> | |
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42 | </refsection> |
43 | ||
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44 | <refsection id='main-conf'> |
45 | <title>Configuration Directories and Precedence</title> | |
46 | ||
a8eaaee7 | 47 | <para>The default configuration is defined during compilation, so a |
e93549ef | 48 | configuration file is only needed when it is necessary to deviate |
b938cb90 | 49 | from those defaults. By default, the configuration file in |
12b42c76 | 50 | <filename>/etc/systemd/</filename> contains commented out entries |
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51 | showing the defaults as a guide to the administrator. This file |
52 | can be edited to create local overrides. | |
53 | </para> | |
54 | ||
55 | <para>When packages need to customize the configuration, they can | |
56 | install configuration snippets in | |
12b42c76 | 57 | <filename>/usr/lib/systemd/*.conf.d/</filename>. Files in |
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58 | <filename>/etc/</filename> are reserved for the local |
59 | administrator, who may use this logic to override the | |
60 | configuration files installed by vendor packages. The main | |
61 | configuration file is read before any of the configuration | |
62 | directories, and has the lowest precedence; entries in a file in | |
63 | any configuration directory override entries in the single | |
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64 | configuration file. Files in the <filename>*.conf.d/</filename> |
65 | configuration subdirectories are sorted by their filename in lexicographic | |
66 | order, regardless of which of the subdirectories they reside in. When | |
67 | multiple files specify the same option, for options which accept just a | |
68 | single value, the entry in the file with the lexicographically latest name | |
69 | takes precedence. For options which accept a list of values, entries are | |
70 | collected as they occur in files sorted lexicographically. It is recommended | |
71 | to prefix all filenames in those subdirectories with a two-digit number and | |
72 | a dash, to simplify the ordering of the files.</para> | |
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73 | |
74 | <para>To disable a configuration file supplied by the vendor, the | |
75 | recommended way is to place a symlink to | |
76 | <filename>/dev/null</filename> in the configuration directory in | |
77 | <filename>/etc/</filename>, with the same filename as the vendor | |
78 | configuration file.</para> | |
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79 | </refsection> |
80 | </refsection> |