<?xml version='1.0'?> <?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"?> <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> <refentry id="systemd-udevd.service"> <refentryinfo> <title>systemd-udevd.service</title> <productname>systemd</productname> <authorgroup> <author> <contrib>Developer</contrib> <firstname>Kay</firstname> <surname>Sievers</surname> <email>kay@vrfy.org</email> </author> </authorgroup> </refentryinfo> <refmeta> <refentrytitle>systemd-udevd.service</refentrytitle> <manvolnum>8</manvolnum> <refmiscinfo class="version"></refmiscinfo> </refmeta> <refnamediv> <refname>systemd-udevd.service</refname> <refname>systemd-udevd-control.socket</refname> <refname>systemd-udevd-kernel.socket</refname> <refname>systemd-udevd</refname> <refpurpose>Device event managing daemon</refpurpose> </refnamediv> <refsynopsisdiv> <para><filename>systemd-udevd.service</filename></para> <para><filename>systemd-udevd-control.socket</filename></para> <para><filename>systemd-udevd-kernel.socket</filename></para> <cmdsynopsis> <command>/usr/lib/systemd/systemd-udevd</command> <arg><option>--daemon</option></arg> <arg><option>--debug</option></arg> <arg><option>--children-max=</option></arg> <arg><option>--exec-delay=</option></arg> <arg><option>--resolve-names=early|late|never</option></arg> <arg><option>--version</option></arg> <arg><option>--help</option></arg> </cmdsynopsis> </refsynopsisdiv> <refsect1><title>Description</title> <para><command>systemd-udevd</command> listens to kernel uevents. For every event, systemd-udevd executes matching instructions specified in udev rules. See <citerefentry> <refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum> </citerefentry>.</para> <para>The behavior of the running daemon can be changed with <command>udevadm control</command>.</para> </refsect1> <refsect1><title>Options</title> <variablelist> <varlistentry> <term><option>--daemon</option></term> <listitem> <para>Detach and run in the background.</para> </listitem> </varlistentry> <varlistentry> <term><option>--debug</option></term> <listitem> <para>Print debug messages to standard error.</para> </listitem> </varlistentry> <varlistentry> <term><option>--children-max=</option></term> <listitem> <para>Limit the number of events executed in parallel.</para> </listitem> </varlistentry> <varlistentry> <term><option>--exec-delay=</option></term> <listitem> <para>Delay the execution of <varname>RUN</varname> instructions by the given number of seconds. This option might be useful when debugging system crashes during coldplug caused by loading non-working kernel modules.</para> </listitem> </varlistentry> <varlistentry> <term><option>--resolve-names=</option></term> <listitem> <para>Specify when systemd-udevd should resolve names of users and groups. When set to <option>early</option> (the default), names will be resolved when the rules are parsed. When set to <option>late</option>, names will be resolved for every event. When set to <option>never</option>, names will never be resolved and all devices will be owned by root.</para> </listitem> </varlistentry> <varlistentry> <term><option>--version</option></term> <listitem> <para>Print version number.</para> </listitem> </varlistentry> <varlistentry> <term><option>--help</option></term> <listitem> <para>Print help text.</para> </listitem> </varlistentry> </variablelist> </refsect1> <refsect1><title>Environment</title> <variablelist class='environment-variables'> <varlistentry> <term><varname>$UDEV_LOG=</varname></term> <listitem> <para>Set the logging priority.</para> </listitem> </varlistentry> </variablelist> </refsect1> <refsect1><title>Kernel command line</title> <variablelist class='kernel-commandline-options'> <para>Parameters starting with "rd." will be read when <command>systemd-udevd</command> is used in an initrd.</para> <varlistentry> <term><varname>udev.log-priority=</varname></term> <term><varname>rd.udev.log-priority=</varname></term> <listitem> <para>Set the logging priority.</para> </listitem> </varlistentry> <varlistentry> <term><varname>udev.children-max=</varname></term> <term><varname>rd.udev.children-max=</varname></term> <listitem> <para>Limit the number of events executed in parallel.</para> </listitem> </varlistentry> <varlistentry> <term><varname>udev.exec-delay=</varname></term> <term><varname>rd.udev.exec-delay=</varname></term> <listitem> <para>Delay the execution of <varname>RUN</varname> instructions by the given number of seconds. This option might be useful when debugging system crashes during coldplug caused by loading non-working kernel modules.</para> </listitem> </varlistentry> <varlistentry> <term><varname>net.ifnames=</varname></term> <listitem> <para>Network interfaces are renamed to give them predictable names when possible. It is enabled by default; specifying 0 disables it.</para> </listitem> </varlistentry> </variablelist> <!-- when adding entries here, consider also adding them in kernel-command-line.xml --> </refsect1> <refsect1><title>Configuration file</title> <para>udev expects its main configuration file at <filename>/etc/udev/udev.conf</filename>. It consists of a set of variables allowing the user to override default udev values. All empty lines or lines beginning with '#' are ignored. The following variables can be set:</para> <variablelist> <varlistentry> <term><varname>udev_log</varname></term> <listitem> <para>The logging priority. Valid values are the numerical syslog priorities or their textual representations: <option>err</option>, <option>info</option> and <option>debug</option>.</para> </listitem> </varlistentry> </variablelist> </refsect1> <refsect1> <title>See Also</title> <para><citerefentry> <refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum> </citerefentry>, <citerefentry> <refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum> </citerefentry></para> </refsect1> </refentry>