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514094f9 | 1 | <?xml version="1.0"?> |
d3fae78f | 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+ | |
96b2fb93 | 7 | Copyright © 2014 Josh Triplett |
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8 | --> |
9 | ||
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10 | <refsection> |
11 | <refsection id='confd'> | |
12 | <title>Configuration Directories and Precedence</title> | |
13 | ||
14 | <para>Configuration files are read from directories in | |
15 | <filename>/etc/</filename>, <filename>/run/</filename>, and | |
16 | <filename>/usr/lib/</filename>, in order of precedence. | |
17 | Each configuration file in these configuration directories shall be named in | |
18 | the style of <filename><replaceable>filename</replaceable>.conf</filename>. | |
19 | Files in <filename>/etc/</filename> override files with the same name in | |
20 | <filename>/run/</filename> and <filename>/usr/lib/</filename>. Files in | |
21 | <filename>/run/</filename> override files with the same name in | |
22 | <filename>/usr/lib/</filename>.</para> | |
23 | ||
24 | <para>Packages should install their configuration files in | |
25 | <filename>/usr/lib/</filename>. Files in <filename>/etc/</filename> are | |
26 | reserved for the local administrator, who may use this logic to override the | |
27 | configuration files installed by vendor packages. All configuration files | |
28 | are sorted by their filename in lexicographic order, regardless of which of | |
29 | the directories they reside in. If multiple files specify the same option, | |
30 | the entry in the file with the lexicographically latest name will take | |
31 | precedence. It is recommended to prefix all filenames with a two-digit number | |
32 | and a dash, to simplify the ordering of the files.</para> | |
33 | ||
34 | <para>If the administrator wants to disable a configuration file supplied by | |
35 | the vendor, the recommended way is to place a symlink to | |
36 | <filename>/dev/null</filename> in the configuration directory in | |
37 | <filename>/etc/</filename>, with the same filename as the vendor | |
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38 | configuration file. If the vendor configuration file is included in |
39 | the initrd image, the image has to be regenerated.</para> | |
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40 | </refsection> |
41 | ||
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42 | <refsection id='main-conf'> |
43 | <title>Configuration Directories and Precedence</title> | |
44 | ||
a8eaaee7 | 45 | <para>The default configuration is defined during compilation, so a |
e93549ef | 46 | configuration file is only needed when it is necessary to deviate |
b938cb90 | 47 | from those defaults. By default, the configuration file in |
12b42c76 | 48 | <filename>/etc/systemd/</filename> contains commented out entries |
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49 | showing the defaults as a guide to the administrator. This file |
50 | can be edited to create local overrides. | |
51 | </para> | |
52 | ||
53 | <para>When packages need to customize the configuration, they can | |
54 | install configuration snippets in | |
12b42c76 | 55 | <filename>/usr/lib/systemd/*.conf.d/</filename>. Files in |
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56 | <filename>/etc/</filename> are reserved for the local |
57 | administrator, who may use this logic to override the | |
58 | configuration files installed by vendor packages. The main | |
59 | configuration file is read before any of the configuration | |
60 | directories, and has the lowest precedence; entries in a file in | |
61 | any configuration directory override entries in the single | |
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62 | configuration file. Files in the <filename>*.conf.d/</filename> |
63 | configuration subdirectories are sorted by their filename in lexicographic | |
64 | order, regardless of which of the subdirectories they reside in. When | |
65 | multiple files specify the same option, for options which accept just a | |
66 | single value, the entry in the file with the lexicographically latest name | |
67 | takes precedence. For options which accept a list of values, entries are | |
68 | collected as they occur in files sorted lexicographically. It is recommended | |
69 | to prefix all filenames in those subdirectories with a two-digit number and | |
70 | a dash, to simplify the ordering of the files.</para> | |
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71 | |
72 | <para>To disable a configuration file supplied by the vendor, the | |
73 | recommended way is to place a symlink to | |
74 | <filename>/dev/null</filename> in the configuration directory in | |
75 | <filename>/etc/</filename>, with the same filename as the vendor | |
76 | configuration file.</para> | |
d3fae78f JT |
77 | </refsection> |
78 | </refsection> |