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
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  17   Lesser General Public License for more details.
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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>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                 lexicographic order, regardless in which of the
  93                 directories they reside. If multiple files specify the
  94                 same variable name, the entry in the file with the
  95                 lexicographically latest name will be applied. It is
  96                 recommended to prefix all filenames with a two-digit
  97                 number and a dash, to simplify the ordering of the
  98                 files.</para>
  99
 100                 <para>If the administrator wants to disable a
 101                 configuration file supplied by the vendor, the
 102                 recommended way is to place a symlink to
 103                 <filename>/dev/null</filename> in
 104                 <filename>/etc/sysctl.d/</filename> bearing the
 105                 same filename.</para>
 106         </refsect1>
 107
 108         <refsect1>
 109                 <title>Example</title>
 110                 <example>
 111                         <title>/etc/sysctl.d/domain-name.conf example:</title>
 112
 113                         <programlisting># Set kernel YP domain name
 114 kernel.domainname=example.com</programlisting>
 115                 </example>
 116         </refsect1>
 117
 118         <refsect1>
 119                 <title>See Also</title>
 120                 <para>
 121                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 122                         <citerefentry><refentrytitle>systemd-sysctl.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 123                         <citerefentry><refentrytitle>systemd-delta</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 124                         <citerefentry><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 125                         <citerefentry><refentrytitle>sysctl.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 126                 </para>
 127         </refsect1>
 128
 129 </refentry>