man/sysctl.d.xml

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   2 <!--*-nxml-*-->
   3 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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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>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>