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<refentry id="udevadm">
  <refentryinfo>
    <title>udevadm</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>udevadm</refentrytitle>
    <manvolnum>8</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>udevadm</refname><refpurpose>udev management tool</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>udevadm</command>
        <arg><option>--debug</option></arg>
        <arg><option>--version</option></arg>
        <arg><option>--help</option></arg>
    </cmdsynopsis>
    <cmdsynopsis>
      <command>udevadm info <replaceable>options</replaceable></command>
    </cmdsynopsis>
    <cmdsynopsis>
      <command>udevadm trigger <optional>options</optional></command>
    </cmdsynopsis>
    <cmdsynopsis>
      <command>udevadm settle <optional>options</optional></command>
    </cmdsynopsis>
    <cmdsynopsis>
      <command>udevadm control <replaceable>command</replaceable></command>
    </cmdsynopsis>
    <cmdsynopsis>
      <command>udevadm monitor <optional>options</optional></command>
    </cmdsynopsis>
    <cmdsynopsis>
      <command>udevadm test <optional>options</optional> <replaceable>devpath</replaceable></command>
    </cmdsynopsis>
    <cmdsynopsis>
      <command>udevadm test-builtin <optional>options</optional> <replaceable>command</replaceable> <replaceable>devpath</replaceable></command>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1><title>Description</title>
    <para><command>udevadm</command> expects a command and command
    specific options.  It controls the runtime behavior of
    <command>systemd-udevd</command>, requests kernel events, manages
    the event queue, and provides simple debugging mechanisms.</para>
  </refsect1>

  <refsect1><title>Options</title>
    <variablelist>
      <varlistentry>
        <term><option>--debug</option></term>
        <listitem>
          <para>Print debug messages to standard error.</para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><option>--version</option></term>
        <listitem>
          <para>Print version number.</para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-h</option></term>
        <term><option>--help</option></term>
        <listitem>
          <para>Print help text.</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <refsect2><title>udevadm info
      <arg choice="opt"><replaceable>options</replaceable></arg>
      <arg choice="opt"><replaceable>devpath</replaceable>|<replaceable>file</replaceable></arg>
    </title>

      <para>Queries the udev database for device information
      stored in the udev database. It can also query the properties
      of a device from its sysfs representation to help creating udev
      rules that match this device.</para>
      <variablelist>
        <varlistentry>
          <term><option>-q</option></term>
          <term><option>--query=<replaceable>TYPE</replaceable></option></term>
          <listitem>
            <para>Query the database for the specified type of device
            data. It needs the <option>--path</option> or
            <option>--name</option> to identify the specified device.
            Valid <replaceable>TYPE</replaceable>s are:
            <constant>name</constant>, <constant>symlink</constant>,
            <constant>path</constant>, <constant>property</constant>,
            <constant>all</constant>.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-p</option></term>
          <term><option>--path=<replaceable>DEVPATH</replaceable></option></term>
          <listitem>
            <para>The <filename>/sys</filename> path of the device to
            query, e.g.
            <filename><optional>/sys</optional>/class/block/sda</filename>.
            Note that this option usually is not very useful, since
            <command>udev</command> can guess the type of the
            argument, so <command>udevadm
            --devpath=/class/block/sda</command> is equivalent to
            <command>udevadm /sys/class/block/sda</command>.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-n</option></term>
          <term><option>--name=<replaceable>FILE</replaceable></option></term>
          <listitem>
            <para>The name of the device node or a symlink to query,
            e.g. <filename><optional>/dev</optional>/sda</filename>.
            Note that this option usually is not very useful, since
            <command>udev</command> can guess the type of the
            argument, so <command>udevadm --name=sda</command> is
            equivalent to <command>udevadm /dev/sda</command>.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-r</option></term>
          <term><option>--root</option></term>
          <listitem>
            <para>Print absolute paths in <command>name</command> or <command>symlink</command>
            query.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-a</option></term>
          <term><option>--attribute-walk</option></term>
          <listitem>
            <para>Print all sysfs properties of the specified device that can be used
            in udev rules to match the specified device. It prints all devices
            along the chain, up to the root of sysfs that can be used in udev rules.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-x</option></term>
          <term><option>--export</option></term>
          <listitem>
            <para>Print output as key/value pairs. Values are enclosed in single quotes.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-P</option></term>
          <term><option>--export-prefix=<replaceable>NAME</replaceable></option></term>
          <listitem>
            <para>Add a prefix to the key name of exported values.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-d</option></term>
          <term><option>--device-id-of-file=<replaceable>FILE</replaceable></option></term>
          <listitem>
            <para>Print major/minor numbers of the underlying device, where the file
            lives on.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-e</option></term>
          <term><option>--export-db</option></term>
          <listitem>
            <para>Export the content of the udev database.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-c</option></term>
          <term><option>--cleanup-db</option></term>
          <listitem>
            <para>Cleanup the udev database.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>--version</option></term>
          <listitem>
            <para>Print version.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-h</option></term>
          <term><option>--help</option></term>
          <listitem>
            <para>Print help text.</para>
          </listitem>
        </varlistentry>
      </variablelist>

      <para>In addition, an optional positional argument can be used
      to specify a device name or a sys path. It must start with
      <filename>/dev</filename> or <filename>/sys</filename>
      respectively.</para>
    </refsect2>

    <refsect2><title>udevadm trigger
      <arg choice="opt"><replaceable>options</replaceable></arg>
      <arg choice="opt" rep="repeat"><replaceable>devpath</replaceable>|<replaceable>file</replaceable></arg></title>
      <para>Request device events from the kernel. Primarily used to replay events at system coldplug time.</para>
      <variablelist>
        <varlistentry>
          <term><option>-v</option></term>
          <term><option>--verbose</option></term>
          <listitem>
            <para>Print the list of devices which will be triggered.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-n</option></term>
          <term><option>--dry-run</option></term>
          <listitem>
            <para>Do not actually trigger the event.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-t</option></term>
          <term><option>--type=<replaceable>TYPE</replaceable></option></term>
          <listitem>
            <para>Trigger a specific type of devices. Valid types are:
            <command>devices</command>, <command>subsystems</command>.
            The default value is <command>devices</command>.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-c</option></term>
          <term><option>--action=<replaceable>ACTION</replaceable></option></term>
          <listitem>
            <para>Type of event to be triggered. The default value is
            <command>change</command>.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-s</option></term>
          <term><option>--subsystem-match=<replaceable>SUBSYSTEM</replaceable></option></term>
          <listitem>
            <para>Trigger events for devices which belong to a
            matching subsystem. This option can be specified multiple
            times and supports shell style pattern matching.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-S</option></term>
          <term><option>--subsystem-nomatch=<replaceable>SUBSYSTEM</replaceable></option></term>
          <listitem>
            <para>Do not trigger events for devices which belong to a matching subsystem. This option
            can be specified multiple times and supports shell style pattern matching.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-a</option></term>
          <term><option>--attr-match=<replaceable>ATTRIBUTE</replaceable>=<replaceable>VALUE</replaceable></option></term>
          <listitem>
            <para>Trigger events for devices with a matching sysfs
            attribute. If a value is specified along with the
            attribute name, the content of the attribute is matched
            against the given value using shell style pattern
            matching. If no value is specified, the existence of the
            sysfs attribute is checked. This option can be specified
            multiple times.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-A</option></term>
          <term><option>--attr-nomatch=<replaceable>ATTRIBUTE</replaceable>=<replaceable>VALUE</replaceable></option></term>
          <listitem>
            <para>Do not trigger events for devices with a matching
            sysfs attribute. If a value is specified along with the
            attribute name, the content of the attribute is matched
            against the given value using shell style pattern
            matching. If no value is specified, the existence of the
            sysfs attribute is checked. This option can be specified
            multiple times.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-p</option></term>
          <term><option>--property-match=<replaceable>PROPERTY</replaceable>=<replaceable>VALUE</replaceable></option></term>
          <listitem>
            <para>Trigger events for devices with a matching property
            value. This option can be specified multiple times and
            supports shell style pattern matching.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-g</option></term>
          <term><option>--tag-match=<replaceable>PROPERTY</replaceable></option></term>
          <listitem>
            <para>Trigger events for devices with a matching tag. This
            option can be specified multiple times.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-y</option></term>
          <term><option>--sysname-match=<replaceable>PATH</replaceable></option></term>
          <listitem>
            <para>Trigger events for devices with a matching sys
            device path. This option can be specified multiple times
            and supports shell style pattern matching.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>--name-match=<replaceable>NAME</replaceable></option></term>
          <listitem>
            <para>Trigger events for devices with a matching
            device path. This option can be specified multiple
            times.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-b</option></term>
          <term><option>--parent-match=<replaceable>SYSPATH</replaceable></option></term>
          <listitem>
            <para>Trigger events for all children of a given
            device.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-h</option></term>
          <term><option>--help</option></term>
          <listitem>
            <para>Print help text.</para>
          </listitem>
        </varlistentry>
      </variablelist>

      <para>In addition, optional positional arguments can be used
      to specify device names or sys paths. They must start with
      <filename>/dev</filename> or <filename>/sys</filename>
      respectively.</para>
    </refsect2>

    <refsect2><title>udevadm settle
      <arg choice="opt"><replaceable>options</replaceable></arg>
    </title>
      <para>Watches the udev event queue, and exits if all current events are handled.</para>
      <variablelist>
        <varlistentry>
          <term><option>-t</option></term>
          <term><option>--timeout=<replaceable>SECONDS</replaceable></option></term>
          <listitem>
            <para>Maximum number of seconds to wait for the event
            queue to become empty. The default value is 120 seconds. A
            value of 0 will check if the queue is empty and always
            return immediately.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-E</option></term>
          <term><option>--exit-if-exists=<replaceable>FILE</replaceable></option></term>
          <listitem>
            <para>Stop waiting if file exists.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-h</option></term>
          <term><option>--help</option></term>
          <listitem>
            <para>Print help text.</para>
          </listitem>
        </varlistentry>
      </variablelist>
    </refsect2>

    <refsect2><title>udevadm control <replaceable>command</replaceable></title>
      <para>Modify the internal state of the running udev daemon.</para>
      <variablelist>
        <varlistentry>
          <term><option>-x</option></term>
          <term><option>--exit</option></term>
          <listitem>
            <para>Signal and wait for systemd-udevd to exit.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-l</option></term>
          <term><option>--log-priority=<replaceable>value</replaceable></option></term>
          <listitem>
            <para>Set the internal log level of
            <filename>systemd-udevd</filename>. Valid values are the
            numerical syslog priorities or their textual
            representations: <option>emerg</option>,
            <option>alert</option>, <option>crit</option>,
            <option>err</option>, <option>warning</option>,
            <option>notice</option>, <option>info</option>, and
            <option>debug</option>.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-s</option></term>
          <term><option>--stop-exec-queue</option></term>
          <listitem>
            <para>Signal systemd-udevd to stop executing new events. Incoming events
            will be queued.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-S</option></term>
          <term><option>--start-exec-queue</option></term>
          <listitem>
            <para>Signal systemd-udevd to enable the execution of events.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-R</option></term>
          <term><option>--reload</option></term>
          <listitem>
            <para>Signal systemd-udevd to reload the rules files and other databases like the kernel
            module index. Reloading rules and databases does not apply any changes to already
            existing devices; the new configuration will only be applied to new events.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-p</option></term>
          <term><option>--property=<replaceable>KEY</replaceable>=<replaceable>value</replaceable></option></term>
          <listitem>
            <para>Set a global property for all events.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-m</option></term>
          <term><option>--children-max=</option><replaceable>value</replaceable></term>
          <listitem>
            <para>Set the maximum number of events, systemd-udevd will handle at the
            same time.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>--timeout=</option><replaceable>seconds</replaceable></term>
          <listitem>
            <para>The maximum number of seconds to wait for a reply from systemd-udevd.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-h</option></term>
          <term><option>--help</option></term>
          <listitem>
            <para>Print help text.</para>
          </listitem>
        </varlistentry>
      </variablelist>
    </refsect2>

    <refsect2><title>udevadm monitor
      <arg choice="opt"><replaceable>options</replaceable></arg>
    </title>
      <para>Listens to the kernel uevents and events sent out by a udev rule
      and prints the devpath of the event to the console. It can be used to analyze the
      event timing, by comparing the timestamps of the kernel uevent and the udev event.
      </para>
      <variablelist>
        <varlistentry>
          <term><option>-k</option></term>
          <term><option>--kernel</option></term>
          <listitem>
            <para>Print the kernel uevents.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-u</option></term>
          <term><option>--udev</option></term>
          <listitem>
            <para>Print the udev event after the rule processing.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-p</option></term>
          <term><option>--property</option></term>
          <listitem>
            <para>Also print the properties of the event.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-s</option></term>
          <term><option>--subsystem-match=<replaceable>string[/string]</replaceable></option></term>
          <listitem>
            <para>Filter events by subsystem[/devtype]. Only udev events with a matching subsystem value will pass.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-t</option></term>
          <term><option>--tag-match=<replaceable>string</replaceable></option></term>
          <listitem>
            <para>Filter events by property. Only udev events with a given tag attached will pass.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-h</option></term>
          <term><option>--help</option></term>
          <listitem>
            <para>Print help text.</para>
          </listitem>
        </varlistentry>
      </variablelist>
    </refsect2>

    <refsect2><title>udevadm test
      <arg choice="opt"><replaceable>options</replaceable></arg>
      <arg><replaceable>devpath</replaceable></arg>
    </title>
      <para>Simulate a udev event run for the given device, and print debug output.</para>
      <variablelist>
        <varlistentry>
          <term><option>-a</option></term>
          <term><option>--action=<replaceable>string</replaceable></option></term>
          <listitem>
            <para>The action string.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-N</option></term>
          <term><option>--resolve-names=<constant>early</constant>|<constant>late</constant>|<constant>never</constant></option></term>
          <listitem>
            <para>Specify when udevadm should resolve names of users
            and groups.  When set to <constant>early</constant> (the
            default), names will be resolved when the rules are
            parsed. When set to <constant>late</constant>, names will
            be resolved for every event. When set to
            <constant>never</constant>, names will never be resolved
            and all devices will be owned by root.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-h</option></term>
          <term><option>--help</option></term>
          <listitem>
            <para>Print help text.</para>
          </listitem>
        </varlistentry>
      </variablelist>
    </refsect2>

    <refsect2><title>udevadm test-builtin
      <arg choice="opt"><replaceable>options</replaceable></arg>
      <arg><replaceable>command</replaceable></arg>
      <arg><replaceable>devpath</replaceable></arg>
    </title>
      <para>Run a built-in command <replaceable>COMMAND</replaceable>
      for device <replaceable>DEVPATH</replaceable>, and print debug
      output.</para>
      <variablelist>
        <varlistentry>
          <term><option>-h</option></term>
          <term><option>--help</option></term>
          <listitem>
            <para>Print help text.</para>
          </listitem>
        </varlistentry>
      </variablelist>
    </refsect2>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para><citerefentry>
        <refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum>
    </citerefentry>,
    <citerefentry>
        <refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum>
    </citerefentry></para>
  </refsect1>
</refentry>
