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79 lines
4.0 KiB
XML
79 lines
4.0 KiB
XML
<?xml version="1.0"?>
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<!DOCTYPE refsection PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
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<!--
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SPDX-License-Identifier: LGPL-2.1+
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Copyright © 2014 Josh Triplett
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-->
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<refsection>
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<refsection id='confd'>
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<title>Configuration Directories and Precedence</title>
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<para>Configuration files are read from directories in
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<filename>/etc/</filename>, <filename>/run/</filename>, and
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<filename>/usr/lib/</filename>, in order of precedence.
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Each configuration file in these configuration directories shall be named in
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the style of <filename><replaceable>filename</replaceable>.conf</filename>.
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Files in <filename>/etc/</filename> override files with the same name in
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<filename>/run/</filename> and <filename>/usr/lib/</filename>. Files in
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<filename>/run/</filename> override files with the same name in
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<filename>/usr/lib/</filename>.</para>
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<para>Packages should install their configuration files in
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<filename>/usr/lib/</filename>. Files in <filename>/etc/</filename> are
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reserved for the local administrator, who may use this logic to override the
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configuration files installed by vendor packages. All configuration files
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are sorted by their filename in lexicographic order, regardless of which of
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the directories they reside in. If multiple files specify the same option,
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the entry in the file with the lexicographically latest name will take
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precedence. It is recommended to prefix all filenames with a two-digit number
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and a dash, to simplify the ordering of the files.</para>
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<para>If the administrator wants to disable a configuration file supplied by
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the vendor, the recommended way is to place a symlink to
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<filename>/dev/null</filename> in the configuration directory in
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<filename>/etc/</filename>, with the same filename as the vendor
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configuration file. If the vendor configuration file is included in
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the initrd image, the image has to be regenerated.</para>
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</refsection>
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<refsection id='main-conf'>
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<title>Configuration Directories and Precedence</title>
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<para>The default configuration is defined during compilation, so a
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configuration file is only needed when it is necessary to deviate
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from those defaults. By default, the configuration file in
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<filename>/etc/systemd/</filename> contains commented out entries
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showing the defaults as a guide to the administrator. This file
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can be edited to create local overrides.
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</para>
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<para>When packages need to customize the configuration, they can
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install configuration snippets in
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<filename>/usr/lib/systemd/*.conf.d/</filename>. Files in
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<filename>/etc/</filename> are reserved for the local
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administrator, who may use this logic to override the
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configuration files installed by vendor packages. The main
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configuration file is read before any of the configuration
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directories, and has the lowest precedence; entries in a file in
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any configuration directory override entries in the single
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configuration file. Files in the <filename>*.conf.d/</filename>
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configuration subdirectories are sorted by their filename in lexicographic
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order, regardless of which of the subdirectories they reside in. When
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multiple files specify the same option, for options which accept just a
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single value, the entry in the file with the lexicographically latest name
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takes precedence. For options which accept a list of values, entries are
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collected as they occur in files sorted lexicographically. It is recommended
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to prefix all filenames in those subdirectories with a two-digit number and
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a dash, to simplify the ordering of the files.</para>
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<para>To disable a configuration file supplied by the vendor, the
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recommended way is to place a symlink to
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<filename>/dev/null</filename> in the configuration directory in
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<filename>/etc/</filename>, with the same filename as the vendor
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configuration file.</para>
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</refsection>
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</refsection>
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