man/systemd-udevd.service.xml

   1 <?xml version='1.0'?>
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   3 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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   5
   6 <refentry id="systemd-udevd.service"
   7           xmlns:xi="http://www.w3.org/2001/XInclude">
   8
   9   <refentryinfo>
  10     <title>systemd-udevd.service</title>
  11     <productname>systemd</productname>
  12     <authorgroup>
  13       <author>
  14         <contrib>Developer</contrib>
  15         <firstname>Kay</firstname>
  16         <surname>Sievers</surname>
  17         <email>kay@vrfy.org</email>
  18       </author>
  19     </authorgroup>
  20   </refentryinfo>
  21
  22   <refmeta>
  23     <refentrytitle>systemd-udevd.service</refentrytitle>
  24     <manvolnum>8</manvolnum>
  25     <refmiscinfo class="version"></refmiscinfo>
  26   </refmeta>
  27
  28   <refnamediv>
  29     <refname>systemd-udevd.service</refname>
  30     <refname>systemd-udevd-control.socket</refname>
  31     <refname>systemd-udevd-kernel.socket</refname>
  32     <refname>systemd-udevd</refname>
  33     <refpurpose>Device event managing daemon</refpurpose>
  34   </refnamediv>
  35
  36   <refsynopsisdiv>
  37     <para><filename>systemd-udevd.service</filename></para>
  38     <para><filename>systemd-udevd-control.socket</filename></para>
  39     <para><filename>systemd-udevd-kernel.socket</filename></para>
  40
  41     <cmdsynopsis>
  42       <command>/usr/lib/systemd/systemd-udevd</command>
  43       <arg><option>--daemon</option></arg>
  44       <arg><option>--debug</option></arg>
  45       <arg><option>--children-max=</option></arg>
  46       <arg><option>--exec-delay=</option></arg>
  47       <arg><option>--event-timeout=</option></arg>
  48       <arg><option>--resolve-names=early|late|never</option></arg>
  49       <arg><option>--version</option></arg>
  50       <arg><option>--help</option></arg>
  51     </cmdsynopsis>
  52
  53   </refsynopsisdiv>
  54
  55   <refsect1><title>Description</title>
  56     <para><command>systemd-udevd</command> listens to kernel uevents.
  57       For every event, systemd-udevd executes matching instructions
  58       specified in udev rules. See <citerefentry>
  59       <refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum>
  60       </citerefentry>.</para>
  61     <para>The behavior of the running daemon can be changed with
  62     <command>udevadm control</command>.</para>
  63   </refsect1>
  64
  65   <refsect1><title>Options</title>
  66     <variablelist>
  67       <varlistentry>
  68         <term><option>--daemon</option></term>
  69         <listitem>
  70           <para>Detach and run in the background.</para>
  71         </listitem>
  72       </varlistentry>
  73
  74       <varlistentry>
  75         <term><option>--debug</option></term>
  76         <listitem>
  77           <para>Print debug messages to standard error.</para>
  78         </listitem>
  79       </varlistentry>
  80
  81       <varlistentry>
  82         <term><option>--children-max=</option></term>
  83         <listitem>
  84           <para>Limit the number of events executed in parallel.</para>
  85         </listitem>
  86       </varlistentry>
  87
  88       <varlistentry>
  89         <term><option>--exec-delay=</option></term>
  90         <listitem>
  91           <para>Delay the execution of <varname>RUN</varname>
  92           instructions by the given number of seconds. This option
  93           might be useful when debugging system crashes during
  94           coldplug caused by loading non-working kernel
  95           modules.</para>
  96         </listitem>
  97       </varlistentry>
  98
  99       <varlistentry>
 100         <term><option>--event-timeout=</option></term>
 101         <listitem>
 102           <para>Set the number of seconds to wait for events to finish. After
 103           this time the event will be terminated. The default is 30 seconds.</para>
 104         </listitem>
 105       </varlistentry>
 106
 107       <varlistentry>
 108         <term><option>--resolve-names=</option></term>
 109         <listitem>
 110           <para>Specify when systemd-udevd should resolve names of users and groups.
 111           When set to <option>early</option> (the default), names will be
 112           resolved when the rules are parsed.  When set to
 113           <option>late</option>, names will be resolved for every event.
 114           When set to <option>never</option>, names will never be resolved
 115           and all devices will be owned by root.</para>
 116         </listitem>
 117       </varlistentry>
 118
 119       <varlistentry>
 120         <term><option>--help</option></term>
 121
 122         <xi:include href="standard-options.xml" xpointer="help-text" />
 123       </varlistentry>
 124       <xi:include href="standard-options.xml" xpointer="version" />
 125     </variablelist>
 126   </refsect1>
 127
 128   <refsect1><title>Environment</title>
 129     <variablelist class='environment-variables'>
 130       <varlistentry>
 131         <term><varname>$UDEV_LOG=</varname></term>
 132         <listitem>
 133           <para>Set the logging priority.</para>
 134         </listitem>
 135       </varlistentry>
 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 logging priority.</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><title>Configuration file</title>
 189    <para>udev expects its main configuration file at <filename>/etc/udev/udev.conf</filename>.
 190    It consists of a set of variables allowing the user to override default udev values. All
 191    empty lines or lines beginning with '#' are ignored. The following variables can be
 192    set:</para>
 193    <variablelist>
 194      <varlistentry>
 195        <term><varname>udev_log</varname></term>
 196        <listitem>
 197          <para>The logging priority. Valid values are the numerical syslog priorities
 198          or their textual representations: <option>err</option>, <option>info</option>
 199          and <option>debug</option>.</para>
 200        </listitem>
 201      </varlistentry>
 202    </variablelist>
 203  </refsect1>
 204
 205   <refsect1>
 206     <title>See Also</title>
 207     <para><citerefentry>
 208         <refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum>
 209       </citerefentry>, <citerefentry>
 210         <refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum>
 211     </citerefentry></para>
 212   </refsect1>
 213 </refentry>