man/systemd-udevd.service.xml

   1 <?xml version='1.0'?>
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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>--resolve-names=early|late|never</option></arg>
  48       <arg><option>--version</option></arg>
  49       <arg><option>--help</option></arg>
  50     </cmdsynopsis>
  51
  52   </refsynopsisdiv>
  53
  54   <refsect1><title>Description</title>
  55     <para><command>systemd-udevd</command> listens to kernel uevents.
  56       For every event, systemd-udevd executes matching instructions
  57       specified in udev rules. See <citerefentry>
  58       <refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum>
  59       </citerefentry>.</para>
  60     <para>The behavior of the running daemon can be changed with
  61     <command>udevadm control</command>.</para>
  62   </refsect1>
  63
  64   <refsect1><title>Options</title>
  65     <variablelist>
  66       <varlistentry>
  67         <term><option>--daemon</option></term>
  68         <listitem>
  69           <para>Detach and run in the background.</para>
  70         </listitem>
  71       </varlistentry>
  72
  73       <varlistentry>
  74         <term><option>--debug</option></term>
  75         <listitem>
  76           <para>Print debug messages to standard error.</para>
  77         </listitem>
  78       </varlistentry>
  79
  80       <varlistentry>
  81         <term><option>--children-max=</option></term>
  82         <listitem>
  83           <para>Limit the number of events executed in parallel.</para>
  84         </listitem>
  85       </varlistentry>
  86
  87       <varlistentry>
  88         <term><option>--exec-delay=</option></term>
  89         <listitem>
  90           <para>Delay the execution of <varname>RUN</varname>
  91           instructions by the given number of seconds. This option
  92           might be useful when debugging system crashes during
  93           coldplug caused by loading non-working kernel
  94           modules.</para>
  95         </listitem>
  96       </varlistentry>
  97
  98       <varlistentry>
  99         <term><option>--resolve-names=</option></term>
 100         <listitem>
 101           <para>Specify when systemd-udevd should resolve names of users and groups.
 102           When set to <option>early</option> (the default), names will be
 103           resolved when the rules are parsed.  When set to
 104           <option>late</option>, names will be resolved for every event.
 105           When set to <option>never</option>, names will never be resolved
 106           and all devices will be owned by root.</para>
 107         </listitem>
 108       </varlistentry>
 109
 110       <varlistentry>
 111         <term><option>--help</option></term>
 112
 113         <xi:include href="standard-options.xml" xpointer="help-text" />
 114       </varlistentry>
 115       <xi:include href="standard-options.xml" xpointer="version" />
 116     </variablelist>
 117   </refsect1>
 118
 119   <refsect1><title>Environment</title>
 120     <variablelist class='environment-variables'>
 121       <varlistentry>
 122         <term><varname>$UDEV_LOG=</varname></term>
 123         <listitem>
 124           <para>Set the logging priority.</para>
 125         </listitem>
 126       </varlistentry>
 127     </variablelist>
 128  </refsect1>
 129
 130   <refsect1><title>Kernel command line</title>
 131     <variablelist class='kernel-commandline-options'>
 132       <para>Parameters starting with "rd." will be read when
 133       <command>systemd-udevd</command> is used in an initrd.</para>
 134       <varlistentry>
 135         <term><varname>udev.log-priority=</varname></term>
 136         <term><varname>rd.udev.log-priority=</varname></term>
 137         <listitem>
 138           <para>Set the logging priority.</para>
 139         </listitem>
 140       </varlistentry>
 141       <varlistentry>
 142         <term><varname>udev.children-max=</varname></term>
 143         <term><varname>rd.udev.children-max=</varname></term>
 144         <listitem>
 145           <para>Limit the number of events executed in parallel.</para>
 146         </listitem>
 147       </varlistentry>
 148       <varlistentry>
 149         <term><varname>udev.exec-delay=</varname></term>
 150         <term><varname>rd.udev.exec-delay=</varname></term>
 151         <listitem>
 152           <para>Delay the execution of <varname>RUN</varname> instructions by the given
 153           number of seconds. This option might be useful when
 154           debugging system crashes during coldplug caused by loading
 155           non-working kernel modules.</para>
 156         </listitem>
 157       </varlistentry>
 158       <varlistentry>
 159         <term><varname>net.ifnames=</varname></term>
 160         <listitem>
 161           <para>Network interfaces are renamed to give them predictable names
 162           when possible. It is enabled by default; specifying 0 disables it.</para>
 163         </listitem>
 164       </varlistentry>
 165     </variablelist>
 166     <!-- when adding entries here, consider also adding them
 167          in kernel-command-line.xml -->
 168  </refsect1>
 169
 170  <refsect1><title>Configuration file</title>
 171    <para>udev expects its main configuration file at <filename>/etc/udev/udev.conf</filename>.
 172    It consists of a set of variables allowing the user to override default udev values. All
 173    empty lines or lines beginning with '#' are ignored. The following variables can be
 174    set:</para>
 175    <variablelist>
 176      <varlistentry>
 177        <term><varname>udev_log</varname></term>
 178        <listitem>
 179          <para>The logging priority. Valid values are the numerical syslog priorities
 180          or their textual representations: <option>err</option>, <option>info</option>
 181          and <option>debug</option>.</para>
 182        </listitem>
 183      </varlistentry>
 184    </variablelist>
 185  </refsect1>
 186
 187   <refsect1>
 188     <title>See Also</title>
 189     <para><citerefentry>
 190         <refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum>
 191       </citerefentry>, <citerefentry>
 192         <refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum>
 193     </citerefentry></para>
 194   </refsect1>
 195 </refentry>