man/systemd-udevd.service.xml

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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   4
   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7
   8   Copyright © 2010-2013 Kay Sievers
   9 -->
  10
  11 <refentry id="systemd-udevd.service"
  12           xmlns:xi="http://www.w3.org/2001/XInclude">
  13
  14   <refentryinfo>
  15     <title>systemd-udevd.service</title>
  16     <productname>systemd</productname>
  17     <authorgroup>
  18       <author>
  19         <contrib>Developer</contrib>
  20         <firstname>Kay</firstname>
  21         <surname>Sievers</surname>
  22         <email>kay@vrfy.org</email>
  23       </author>
  24     </authorgroup>
  25   </refentryinfo>
  26
  27   <refmeta>
  28     <refentrytitle>systemd-udevd.service</refentrytitle>
  29     <manvolnum>8</manvolnum>
  30   </refmeta>
  31
  32   <refnamediv>
  33     <refname>systemd-udevd.service</refname>
  34     <refname>systemd-udevd-control.socket</refname>
  35     <refname>systemd-udevd-kernel.socket</refname>
  36     <refname>systemd-udevd</refname>
  37     <refpurpose>Device event managing daemon</refpurpose>
  38   </refnamediv>
  39
  40   <refsynopsisdiv>
  41     <para><filename>systemd-udevd.service</filename></para>
  42     <para><filename>systemd-udevd-control.socket</filename></para>
  43     <para><filename>systemd-udevd-kernel.socket</filename></para>
  44
  45     <cmdsynopsis>
  46       <command>/usr/lib/systemd/systemd-udevd</command>
  47       <arg><option>--daemon</option></arg>
  48       <arg><option>--debug</option></arg>
  49       <arg><option>--children-max=</option></arg>
  50       <arg><option>--exec-delay=</option></arg>
  51       <arg><option>--event-timeout=</option></arg>
  52       <arg><option>--resolve-names=early|late|never</option></arg>
  53       <arg><option>--version</option></arg>
  54       <arg><option>--help</option></arg>
  55     </cmdsynopsis>
  56
  57   </refsynopsisdiv>
  58
  59   <refsect1><title>Description</title>
  60     <para><command>systemd-udevd</command> listens to kernel uevents.
  61     For every event, systemd-udevd executes matching instructions
  62     specified in udev rules. See <citerefentry>
  63     <refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum>
  64     </citerefentry>.</para>
  65
  66     <para>The behavior of the daemon can be configured using
  67     <citerefentry><refentrytitle>udev.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  68     its command line options, environment variables, and on the kernel
  69     command line, or changed dynamically with <command>udevadm
  70     control</command>.
  71     </para>
  72   </refsect1>
  73
  74   <refsect1><title>Options</title>
  75     <variablelist>
  76       <varlistentry>
  77         <term><option>-d</option></term>
  78         <term><option>--daemon</option></term>
  79         <listitem>
  80           <para>Detach and run in the background.</para>
  81         </listitem>
  82       </varlistentry>
  83
  84       <varlistentry>
  85         <term><option>-D</option></term>
  86         <term><option>--debug</option></term>
  87         <listitem>
  88           <para>Print debug messages to standard error.</para>
  89         </listitem>
  90       </varlistentry>
  91
  92       <varlistentry>
  93         <term><option>-c=</option></term>
  94         <term><option>--children-max=</option></term>
  95         <listitem>
  96           <para>Limit the number of events executed in parallel.</para>
  97         </listitem>
  98       </varlistentry>
  99
 100       <varlistentry>
 101         <term><option>-e=</option></term>
 102         <term><option>--exec-delay=</option></term>
 103         <listitem>
 104           <para>Delay the execution of <varname>RUN</varname>
 105           instructions by the given number of seconds. This option
 106           might be useful when debugging system crashes during
 107           coldplug caused by loading non-working kernel
 108           modules.</para>
 109         </listitem>
 110       </varlistentry>
 111
 112       <varlistentry>
 113         <term><option>-t=</option></term>
 114         <term><option>--event-timeout=</option></term>
 115         <listitem>
 116           <para>Set the number of seconds to wait for events to finish. After
 117           this time, the event will be terminated. The default is 180 seconds.</para>
 118         </listitem>
 119       </varlistentry>
 120
 121       <varlistentry>
 122         <term><option>-N=</option></term>
 123         <term><option>--resolve-names=</option></term>
 124         <listitem>
 125           <para>Specify when systemd-udevd should resolve names of users and groups.
 126           When set to <option>early</option> (the default), names will be
 127           resolved when the rules are parsed.  When set to
 128           <option>late</option>, names will be resolved for every event.
 129           When set to <option>never</option>, names will never be resolved
 130           and all devices will be owned by root.</para>
 131         </listitem>
 132       </varlistentry>
 133
 134       <xi:include href="standard-options.xml" xpointer="help" />
 135       <xi:include href="standard-options.xml" xpointer="version" />
 136     </variablelist>
 137   </refsect1>
 138
 139   <refsect1><title>Kernel command line</title>
 140     <variablelist class='kernel-commandline-options'>
 141       <para>Parameters starting with "rd." will be read when
 142       <command>systemd-udevd</command> is used in an initrd.</para>
 143       <varlistentry>
 144         <term><varname>udev.log_priority=</varname></term>
 145         <term><varname>rd.udev.log_priority=</varname></term>
 146         <listitem>
 147           <para>Set the log level.</para>
 148         </listitem>
 149       </varlistentry>
 150       <varlistentry>
 151         <term><varname>udev.children_max=</varname></term>
 152         <term><varname>rd.udev.children_max=</varname></term>
 153         <listitem>
 154           <para>Limit the number of events executed in parallel.</para>
 155         </listitem>
 156       </varlistentry>
 157       <varlistentry>
 158         <term><varname>udev.exec_delay=</varname></term>
 159         <term><varname>rd.udev.exec_delay=</varname></term>
 160         <listitem>
 161           <para>Delay the execution of <varname>RUN</varname> instructions by the given
 162           number of seconds. This option might be useful when
 163           debugging system crashes during coldplug caused by loading
 164           non-working kernel modules.</para>
 165         </listitem>
 166       </varlistentry>
 167       <varlistentry>
 168         <term><varname>udev.event_timeout=</varname></term>
 169         <term><varname>rd.udev.event_timeout=</varname></term>
 170         <listitem>
 171           <para>Wait for events to finish up to the given number
 172           of seconds. This option might be useful if events are
 173           terminated due to kernel drivers taking too long to initialize.</para>
 174         </listitem>
 175       </varlistentry>
 176       <varlistentry>
 177         <term><varname>net.ifnames=</varname></term>
 178         <listitem>
 179           <para>Network interfaces are renamed to give them predictable names
 180           when possible. It is enabled by default; specifying 0 disables it.</para>
 181         </listitem>
 182       </varlistentry>
 183     </variablelist>
 184     <!-- when adding entries here, consider also adding them
 185          in kernel-command-line.xml -->
 186  </refsect1>
 187
 188   <refsect1>
 189     <title>See Also</title>
 190     <para>
 191       <citerefentry><refentrytitle>udev.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 192       <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 193       <citerefentry><refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 194     </para>
 195   </refsect1>
 196 </refentry>