man/sysctl.d.xml

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   2 <!--*-nxml-*-->
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   5   This file is part of systemd.
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   7   Copyright 2011 Lennart Poettering
   8
   9   systemd is free software; you can redistribute it and/or modify it
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  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><command>systemd</command> uses configuration
  58                 files from the above directories to configure
  59                 <citerefentry><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>
  60                 kernel parameters during boot.</para>
  61         </refsect1>
  62
  63         <refsect1>
  64                 <title>Configuration Format</title>
  65
  66                 <para>The configuration files contain a list of
  67                 variable assignments, separated by newlines. Empty
  68                 lines and lines whose first non-whitespace character
  69                 is # or ; are ignored.</para>
  70
  71                 <para>Note that both / and . are accepted as label
  72                 separators within sysctl variable
  73                 names. <literal>kernel.domainname=foo</literal> and
  74                 <literal>kernel/domainname=foo</literal> hence are
  75                 entirely equivalent.</para>
  76
  77                 <para>Each configuration file shall be named in the
  78                 style of <filename>&lt;program&gt;.conf</filename>.
  79                 Files in <filename>/run/</filename> override files
  80                 with the same name in <filename>/usr/lib/</filename>.
  81                 Files in <filename>/etc</filename> override files with
  82                 the same name in <filename>/run/</filename> and
  83                 <filename>/usr/lib/</filename>. Packages should
  84                 install their configuration files in
  85                 <filename>/usr/lib/</filename>. Files in
  86                 <filename>/etc/</filename> are reserved for the local
  87                 administrator, who may use this logic to override the
  88                 configuration installed by vendor packages. All
  89                 configuration files are sorted by their name in
  90                 alphabetical order, regardless in which of the
  91                 directories they reside, to guarantee that a specific
  92                 configuration file takes precedence over another file
  93                 with an alphabetically earlier name, if both files
  94                 contain the same variable setting.</para>
  95
  96                 <para>If the administrator wants to disable a
  97                 configuration file supplied by the vendor the
  98                 recommended way is to place a symlink to
  99                 <filename>/dev/null</filename> in
 100                 <filename>/etc/sysctl.d</filename> carrying with the
 101                 same name.</para>
 102         </refsect1>
 103
 104         <refsect1>
 105                 <title>Example</title>
 106                 <example>
 107                         <title>/etc/sysctl.d/domain-name.conf example:</title>
 108
 109                         <programlisting># Set kernel YP domain name
 110 kernel.domainname=example.com</programlisting>
 111                 </example>
 112         </refsect1>
 113
 114         <refsect1>
 115                 <title>See Also</title>
 116                 <para>
 117                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 118                         <citerefentry><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 119                         <citerefentry><refentrytitle>sysctl.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 120                 </para>
 121         </refsect1>
 122
 123 </refentry>