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   </refmeta>
  26
  27   <refnamediv>
  28     <refname>systemd-udevd.service</refname>
  29     <refname>systemd-udevd-control.socket</refname>
  30     <refname>systemd-udevd-kernel.socket</refname>
  31     <refname>systemd-udevd</refname>
  32     <refpurpose>Device event managing daemon</refpurpose>
  33   </refnamediv>
  34
  35   <refsynopsisdiv>
  36     <para><filename>systemd-udevd.service</filename></para>
  37     <para><filename>systemd-udevd-control.socket</filename></para>
  38     <para><filename>systemd-udevd-kernel.socket</filename></para>
  39
  40     <cmdsynopsis>
  41       <command>/usr/lib/systemd/systemd-udevd</command>
  42       <arg><option>--daemon</option></arg>
  43       <arg><option>--debug</option></arg>
  44       <arg><option>--children-max=</option></arg>
  45       <arg><option>--exec-delay=</option></arg>
  46       <arg><option>--event-timeout=</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
  61     <para>The behavior of the daemon can be configured using
  62     <citerefentry><refentrytitle>udev.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  63     its command-line options, environment variables, and on the kernel
  64     command-line, or changed dynamically with <command>udevadm
  65     control</command>.
  66     </para>
  67   </refsect1>
  68
  69   <refsect1><title>Options</title>
  70     <variablelist>
  71       <varlistentry>
  72         <term><option>--daemon</option></term>
  73         <listitem>
  74           <para>Detach and run in the background.</para>
  75         </listitem>
  76       </varlistentry>
  77
  78       <varlistentry>
  79         <term><option>--debug</option></term>
  80         <listitem>
  81           <para>Print debug messages to standard error.</para>
  82         </listitem>
  83       </varlistentry>
  84
  85       <varlistentry>
  86         <term><option>--children-max=</option></term>
  87         <listitem>
  88           <para>Limit the number of events executed in parallel.</para>
  89         </listitem>
  90       </varlistentry>
  91
  92       <varlistentry>
  93         <term><option>--exec-delay=</option></term>
  94         <listitem>
  95           <para>Delay the execution of <varname>RUN</varname>
  96           instructions by the given number of seconds. This option
  97           might be useful when debugging system crashes during
  98           coldplug caused by loading non-working kernel
  99           modules.</para>
 100         </listitem>
 101       </varlistentry>
 102
 103       <varlistentry>
 104         <term><option>--event-timeout=</option></term>
 105         <listitem>
 106           <para>Set the number of seconds to wait for events to finish. After
 107           this time the event will be terminated. The default is 30 seconds.</para>
 108         </listitem>
 109       </varlistentry>
 110
 111       <varlistentry>
 112         <term><option>--resolve-names=</option></term>
 113         <listitem>
 114           <para>Specify when systemd-udevd should resolve names of users and groups.
 115           When set to <option>early</option> (the default), names will be
 116           resolved when the rules are parsed.  When set to
 117           <option>late</option>, names will be resolved for every event.
 118           When set to <option>never</option>, names will never be resolved
 119           and all devices will be owned by root.</para>
 120         </listitem>
 121       </varlistentry>
 122
 123       <varlistentry>
 124         <term><option>--help</option></term>
 125
 126         <xi:include href="standard-options.xml" xpointer="help-text" />
 127       </varlistentry>
 128       <xi:include href="standard-options.xml" xpointer="version" />
 129     </variablelist>
 130   </refsect1>
 131
 132   <refsect1><title>Environment</title>
 133     <variablelist class='environment-variables'>
 134       <varlistentry>
 135         <term><varname>$UDEV_LOG=</varname></term>
 136         <listitem>
 137           <para>Set the log level.</para>
 138         </listitem>
 139       </varlistentry>
 140     </variablelist>
 141  </refsect1>
 142
 143   <refsect1><title>Kernel command line</title>
 144     <variablelist class='kernel-commandline-options'>
 145       <para>Parameters starting with "rd." will be read when
 146       <command>systemd-udevd</command> is used in an initrd.</para>
 147       <varlistentry>
 148         <term><varname>udev.log-priority=</varname></term>
 149         <term><varname>rd.udev.log-priority=</varname></term>
 150         <listitem>
 151           <para>Set the log level.</para>
 152         </listitem>
 153       </varlistentry>
 154       <varlistentry>
 155         <term><varname>udev.children-max=</varname></term>
 156         <term><varname>rd.udev.children-max=</varname></term>
 157         <listitem>
 158           <para>Limit the number of events executed in parallel.</para>
 159         </listitem>
 160       </varlistentry>
 161       <varlistentry>
 162         <term><varname>udev.exec-delay=</varname></term>
 163         <term><varname>rd.udev.exec-delay=</varname></term>
 164         <listitem>
 165           <para>Delay the execution of <varname>RUN</varname> instructions by the given
 166           number of seconds. This option might be useful when
 167           debugging system crashes during coldplug caused by loading
 168           non-working kernel modules.</para>
 169         </listitem>
 170       </varlistentry>
 171       <varlistentry>
 172         <term><varname>udev.event-timeout=</varname></term>
 173         <term><varname>rd.udev.event-timeout=</varname></term>
 174         <listitem>
 175           <para>Wait for events to finish up to the given number
 176           of seconds. This option might be useful if events are
 177           terminated due to kernel drivers taking too long to initialize.</para>
 178         </listitem>
 179       </varlistentry>
 180       <varlistentry>
 181         <term><varname>net.ifnames=</varname></term>
 182         <listitem>
 183           <para>Network interfaces are renamed to give them predictable names
 184           when possible. It is enabled by default; specifying 0 disables it.</para>
 185         </listitem>
 186       </varlistentry>
 187     </variablelist>
 188     <!-- when adding entries here, consider also adding them
 189          in kernel-command-line.xml -->
 190  </refsect1>
 191
 192   <refsect1>
 193     <title>See Also</title>
 194     <para>
 195       <citerefentry><refentrytitle>udev.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 196       <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 197       <citerefentry><refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 198     </para>
 199   </refsect1>
 200 </refentry>