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>Wait for the event to finish up to the given
 103           number of seconds. After this time the event will
 104           be terminated. Default is 30.</para>
 105         </listitem>
 106       </varlistentry>
 107
 108       <varlistentry>
 109         <term><option>--resolve-names=</option></term>
 110         <listitem>
 111           <para>Specify when systemd-udevd should resolve names of users and groups.
 112           When set to <option>early</option> (the default), names will be
 113           resolved when the rules are parsed.  When set to
 114           <option>late</option>, names will be resolved for every event.
 115           When set to <option>never</option>, names will never be resolved
 116           and all devices will be owned by root.</para>
 117         </listitem>
 118       </varlistentry>
 119
 120       <varlistentry>
 121         <term><option>--help</option></term>
 122
 123         <xi:include href="standard-options.xml" xpointer="help-text" />
 124       </varlistentry>
 125       <xi:include href="standard-options.xml" xpointer="version" />
 126     </variablelist>
 127   </refsect1>
 128
 129   <refsect1><title>Environment</title>
 130     <variablelist class='environment-variables'>
 131       <varlistentry>
 132         <term><varname>$UDEV_LOG=</varname></term>
 133         <listitem>
 134           <para>Set the logging priority.</para>
 135         </listitem>
 136       </varlistentry>
 137     </variablelist>
 138  </refsect1>
 139
 140   <refsect1><title>Kernel command line</title>
 141     <variablelist class='kernel-commandline-options'>
 142       <para>Parameters starting with "rd." will be read when
 143       <command>systemd-udevd</command> is used in an initrd.</para>
 144       <varlistentry>
 145         <term><varname>udev.log-priority=</varname></term>
 146         <term><varname>rd.udev.log-priority=</varname></term>
 147         <listitem>
 148           <para>Set the logging priority.</para>
 149         </listitem>
 150       </varlistentry>
 151       <varlistentry>
 152         <term><varname>udev.children-max=</varname></term>
 153         <term><varname>rd.udev.children-max=</varname></term>
 154         <listitem>
 155           <para>Limit the number of events executed in parallel.</para>
 156         </listitem>
 157       </varlistentry>
 158       <varlistentry>
 159         <term><varname>udev.exec-delay=</varname></term>
 160         <term><varname>rd.udev.exec-delay=</varname></term>
 161         <listitem>
 162           <para>Delay the execution of <varname>RUN</varname> instructions by the given
 163           number of seconds. This option might be useful when
 164           debugging system crashes during coldplug caused by loading
 165           non-working kernel modules.</para>
 166         </listitem>
 167       </varlistentry>
 168       <varlistentry>
 169         <term><varname>udev.event-timeout=</varname></term>
 170         <term><varname>rd.udev.event-timeout=</varname></term>
 171         <listitem>
 172           <para>Wait for events to finish up to the given number
 173           of seconds. This option might be useful if events are
 174           terminated due to a timeout in large configurations.</para>
 175         </listitem>
 176       </varlistentry>
 177       <varlistentry>
 178         <term><varname>net.ifnames=</varname></term>
 179         <listitem>
 180           <para>Network interfaces are renamed to give them predictable names
 181           when possible. It is enabled by default; specifying 0 disables it.</para>
 182         </listitem>
 183       </varlistentry>
 184     </variablelist>
 185     <!-- when adding entries here, consider also adding them
 186          in kernel-command-line.xml -->
 187  </refsect1>
 188
 189  <refsect1><title>Configuration file</title>
 190    <para>udev expects its main configuration file at <filename>/etc/udev/udev.conf</filename>.
 191    It consists of a set of variables allowing the user to override default udev values. All
 192    empty lines or lines beginning with '#' are ignored. The following variables can be
 193    set:</para>
 194    <variablelist>
 195      <varlistentry>
 196        <term><varname>udev_log</varname></term>
 197        <listitem>
 198          <para>The logging priority. Valid values are the numerical syslog priorities
 199          or their textual representations: <option>err</option>, <option>info</option>
 200          and <option>debug</option>.</para>
 201        </listitem>
 202      </varlistentry>
 203    </variablelist>
 204  </refsect1>
 205
 206   <refsect1>
 207     <title>See Also</title>
 208     <para><citerefentry>
 209         <refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum>
 210       </citerefentry>, <citerefentry>
 211         <refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum>
 212     </citerefentry></para>
 213   </refsect1>
 214 </refentry>