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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>

<refmiscinfo class="version"></refmiscinfo>

</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 hwdb <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 <optional><replaceable>OPTIONS</replaceable></optional> <optional><replaceable>DEVPATH</replaceable>|<replaceable>FILE</replaceable></optional></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>

</refsect2>

<refsect2><title>udevadm trigger <optional>options</optional></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>NAME</replaceable></option></term>

<listitem>

<para>Trigger events for devices with a matching sys

device name. This option can be specified multiple times

and supports shell style pattern matching.</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>

</refsect2>

<refsect2><title>udevadm settle <optional>options</optional></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 systemd-udevd. Valid values are the numerical

syslog priorities or their textual representations: <option>err</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 <optional>options</optional></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 hwdb <optional>options</optional></title>

<para>Maintain the hardware database index in <filename>/etc/udev/hwdb.bin</filename>.</para>

<variablelist>

<varlistentry>

<term><option>-u</option></term>

<term><option>--update</option></term>

<listitem>

<para>Compile the hardware database information located in /usr/lib/udev/hwdb.d/,

/etc/udev/hwdb.d/ and store it in <filename>/etc/udev/hwdb.bin</filename>. This should be done after

any update to the source files; it will not be called automatically. The running

udev daemon will detect a new database on its own and does not need to be

notified about it.</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>-t</option></term>

<term><option>--test=<replaceable>string</replaceable></option></term>

<listitem>

<para>Query the database with a modalias string, and print the

retrieved properties.</para>

</listitem>

</varlistentry>

<varlistentry>

<term><option>-r</option></term>

<term><option>--root=<replaceable>string</replaceable></option></term>

<listitem>

<para>Alternative root path in the file system for reading and writing files.</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 <optional>options</optional> <replaceable>devpath</replaceable></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 <optional>options</optional> <replaceable>COMMAND</replaceable> <replaceable>DEVPATH</replaceable></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>