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zsh_completion: Split out zsh _systemd-analyze
[elogind.git] / man / sysctl.d.xml
1 <?xml version="1.0"?>
2 <!--*-nxml-*-->
3 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4 <!--
5   This file is part of systemd.
6
7   Copyright 2011 Lennart Poettering
8
9   systemd is free software; you can redistribute it and/or modify it
10   under the terms of the GNU Lesser General Public License as published by
11   the Free Software Foundation; either version 2.1 of the License, or
12   (at your option) any later version.
13
14   systemd is distributed in the hope that it will be useful, but
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16   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17   Lesser General Public License for more details.
18
19   You should have received a copy of the GNU Lesser General Public License
20   along with systemd; If not, see <http://www.gnu.org/licenses/>.
21 -->
22 <refentry id="sysctl.d">
23
24         <refentryinfo>
25                 <title>sysctl.d</title>
26                 <productname>systemd</productname>
27
28                 <authorgroup>
29                         <author>
30                                 <contrib>Developer</contrib>
31                                 <firstname>Lennart</firstname>
32                                 <surname>Poettering</surname>
33                                 <email>lennart@poettering.net</email>
34                         </author>
35                 </authorgroup>
36         </refentryinfo>
37
38         <refmeta>
39                 <refentrytitle>sysctl.d</refentrytitle>
40                 <manvolnum>5</manvolnum>
41         </refmeta>
42
43         <refnamediv>
44                 <refname>sysctl.d</refname>
45                 <refpurpose>Configure kernel parameters at boot</refpurpose>
46         </refnamediv>
47
48         <refsynopsisdiv>
49                 <para><filename>/etc/sysctl.d/*.conf</filename></para>
50                 <para><filename>/run/sysctl.d/*.conf</filename></para>
51                 <para><filename>/usr/lib/sysctl.d/*.conf</filename></para>
52         </refsynopsisdiv>
53
54         <refsect1>
55                 <title>Description</title>
56
57                 <para>At boot,
58                 <citerefentry><refentrytitle>systemd-sysctl.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
59                 reads configuration files from the above directories
60                 to configure
61                 <citerefentry><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>
62                 kernel parameters.</para>
63         </refsect1>
64
65         <refsect1>
66                 <title>Configuration Format</title>
67
68                 <para>The configuration files contain a list of
69                 variable assignments, separated by newlines. Empty
70                 lines and lines whose first non-whitespace character
71                 is # or ; are ignored.</para>
72
73                 <para>Note that both / and . are accepted as label
74                 separators within sysctl variable
75                 names. <literal>kernel.domainname=foo</literal> and
76                 <literal>kernel/domainname=foo</literal> hence are
77                 entirely equivalent.</para>
78
79                 <para>Each configuration file shall be named in the
80                 style of <filename><replaceable>program</replaceable>.conf</filename>.
81                 Files in <filename>/etc/</filename> override files
82                 with the same name in <filename>/usr/lib/</filename>
83                 and <filename>/run/</filename>.  Files in
84                 <filename>/run/</filename> override files with the same
85                 name in <filename>/usr/lib/</filename>. Packages
86                 should install their configuration files in
87                 <filename>/usr/lib/</filename>. Files in
88                 <filename>/etc/</filename> are reserved for the local
89                 administrator, who may use this logic to override the
90                 configuration files installed by vendor packages. All
91                 configuration files are sorted by their filename in
92                 alphabetical order, regardless in which of the
93                 directories they reside, to guarantee that a specific
94                 configuration file takes precedence over another file
95                 with an alphabetically later name, if both files
96                 contain the same variable setting.</para>
97
98                 <para>If the administrator wants to disable a
99                 configuration file supplied by the vendor, the
100                 recommended way is to place a symlink to
101                 <filename>/dev/null</filename> in
102                 <filename>/etc/sysctl.d/</filename> bearing the
103                 same filename.</para>
104         </refsect1>
105
106         <refsect1>
107                 <title>Example</title>
108                 <example>
109                         <title>/etc/sysctl.d/domain-name.conf example:</title>
110
111                         <programlisting># Set kernel YP domain name
112 kernel.domainname=example.com</programlisting>
113                 </example>
114         </refsect1>
115
116         <refsect1>
117                 <title>See Also</title>
118                 <para>
119                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
120                         <citerefentry><refentrytitle>systemd-sysctl.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
121                         <citerefentry><refentrytitle>systemd-delta</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
122                         <citerefentry><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
123                         <citerefentry><refentrytitle>sysctl.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
124                 </para>
125         </refsect1>
126
127 </refentry>