man/systemd-udevd.service.xml

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