Query the database for the specified type of device data. Valid TYPEs are: name, symlink, path, property, all.

When showing device properties using the --query=property option, limit display to properties specified in the argument. The argument should be a comma-separated list of property names. If not specified, all known properties are shown.

When showing device properties using the --query=property option, print only their values, and skip the property name and "=".

Cannot be used together with -x/--export or -P/--export-prefix.

The /sys/ path of the device to query, e.g. [/sys/]/class/block/sda. This option is an alternative to the positional argument with a /sys/ prefix. udevadm info --path=/class/block/sda is equivalent to udevadm info /sys/class/block/sda.

The name of the device node or a symlink to query, e.g. [/dev/]/sda. This option is an alternative to the positional argument with a /dev/ prefix. udevadm info --name=sda is equivalent to udevadm info /dev/sda.

Print absolute paths in name or symlink query.

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.

Display a sysfs tree. This recursively iterates through the sysfs hierarchy and displays it in a tree structure. If a path is specified only the subtree below and its parent directories are shown. This will show both device and subsystem items.

Print output as key/value pairs. Values are enclosed in single quotes. This takes effects only when --query=property or --device-id-of-file=FILE is specified.

Add a prefix to the key name of exported values. This implies --export.

Print major/minor numbers of the underlying device, where the file lives on. If this is specified, all positional arguments are ignored.

Export the content of the udev database.

Cleanup the udev database.

Wait for device to be initialized. If argument SECONDS is not specified, the default is to wait forever.

Print a short help text and exit.

Do not pipe output into a pager.

Print the list of devices which will be triggered.

Do not actually trigger the event.

Suppress error logging in triggering events.

Trigger a specific type of devices. Valid types are "all", "devices", and "subsystems". The default value is "devices".

Type of event to be triggered. Possible actions are "add", "remove", "change", "move", "online", "offline", "bind", and "unbind". Also, the special value "help" can be used to list the possible actions. The default value is "change".

Takes a comma separated list of subsystems. When triggering events for devices, the devices from the specified subsystems and their parents are triggered first. For example, if --prioritized-subsystem=block,net, then firstly all block devices and their parents are triggered, in the next all network devices and their parents are triggered, and lastly the other devices are triggered. This option can be specified multiple times, and in that case the lists of the subsystems will be merged. That is, --prioritized-subsystem=block --prioritized-subsystem=net is equivalent to --prioritized-subsystem=block,net.

Trigger events for devices which belong to a matching subsystem. This option supports shell style pattern matching. When this option is specified more than once, then each matching result is ORed, that is, all the devices in each subsystem are triggered.

Do not trigger events for devices which belong to a matching subsystem. This option supports shell style pattern matching. When this option is specified more than once, then each matching result is ANDed, that is, devices which do not match all specified subsystems are triggered.

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. When this option is specified multiple times, then each matching result is ANDed, that is, only devices which have all specified attributes are triggered.

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. When this option is specified multiple times, then each matching result is ANDed, that is, only devices which have none of the specified attributes are triggered.

Trigger events for devices with a matching property value. This option supports shell style pattern matching. When this option is specified more than once, then each matching result is ORed, that is, devices which have one of the specified properties are triggered.

Trigger events for devices with a matching tag. When this option is specified multiple times, then each matching result is ANDed, that is, devices which have all specified tags are triggered.

Trigger events for devices for which the last component (i.e. the filename) of the /sys/ path matches the specified PATH. This option supports shell style pattern matching. When this option is specified more than once, then each matching result is ORed, that is, all devices which have any of the specified NAME are triggered.

Trigger events for devices with a matching device path. When this option is specified more than once, then each matching result is ORed, that is, all specified devices are triggered.

Trigger events for all children of a given device. When this option is specified more than once, then each matching result is ORed, that is, all children of each specified device are triggered.

When --initialized-match is specified, trigger events for devices that are already initialized by systemd-udevd, and skip devices that are not initialized yet.

When --initialized-nomatch is specified, trigger events for devices that are not initialized by systemd-udevd yet, and skip devices that are already initialized.

Typically, it is essential that applications which intend to use such a match, make sure a suitable udev rule is installed that sets at least one property on devices that shall be matched. See also Initialized Devices section below for more details.

WARNING: --initialized-nomatch can potentially save a significant amount of time compared to re-triggering all devices in the system and e.g. can be used to optimize boot time. However, this is not safe to be used in a boot sequence in general. Especially, when udev rules for a device depend on its parent devices (e.g. "ATTRS" or "IMPORT{parent}" keys, see udev(7) for more details), the final state of the device becomes easily unstable with this option.

Apart from triggering events, also waits for those events to finish. Note that this is different from calling udevadm settle. udevadm settle waits for all events to finish. This option only waits for events triggered by the same command to finish.

Trigger the synthetic device events, and associate a randomized UUID with each. These UUIDs are printed to standard output, one line for each event. These UUIDs are included in the uevent environment block (in the "SYNTH_UUID=" property) and may be used to track delivery of the generated events.

Before triggering uevents, wait for systemd-udevd daemon to be initialized. Optionally takes timeout value. Default timeout is 5 seconds. This is equivalent to invoke invoking udevadm control --ping before udevadm trigger.

Print a short help text and exit.

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. A non-zero value will return an exit code of 0 if queue became empty before timeout was reached, non-zero otherwise.

Stop waiting if file exists.

Print a short help text and exit.

Signal and wait for systemd-udevd to exit. No option except for --timeout can be specified after this option. Note that systemd-udevd.service contains Restart=always and so as a result, this option restarts systemd-udevd. If you want to stop systemd-udevd.service, please use the following:

systemctl stop systemd-udevd-control.socket systemd-udevd-kernel.socket systemd-udevd.service

Set the internal log level of systemd-udevd. Valid values are the numerical syslog priorities or their textual representations: emerg, alert, crit, err, warning, notice, info, and debug.

Signal systemd-udevd to stop executing new events. Incoming events will be queued.

Signal systemd-udevd to enable the execution of events.

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.

Set a global property for all events.

Set the maximum number of events, systemd-udevd will handle at the same time.

Send a ping message to systemd-udevd and wait for the reply. This may be useful to check that systemd-udevd daemon is running.

The maximum number of seconds to wait for a reply from systemd-udevd.

Print a short help text and exit.

Print the kernel uevents.

Print the udev event after the rule processing.

Also print the properties of the event.

Filter kernel uevents and udev events by subsystem[/devtype]. Only events with a matching subsystem value will pass. When this option is specified more than once, then each matching result is ORed, that is, all devices in the specified subsystems are monitored.

Filter udev events by tag. Only udev events with a given tag attached will pass. When this option is specified more than once, then each matching result is ORed, that is, devices which have one of the specified tags are monitored.

Print a short help text and exit.

Type of event to be simulated. Possible actions are "add", "remove", "change", "move", "online", "offline", "bind", and "unbind". Also, the special value "help" can be used to list the possible actions. The default value is "add".

Specify when udevadm should resolve names of users and groups. When set to early (the default), names will be resolved when the rules are parsed. When set to late, names will be resolved for every event. When set to never, names will never be resolved and all devices will be owned by root.

Print a short help text and exit.

Type of event to be simulated. Possible actions are "add", "remove", "change", "move", "online", "offline", "bind", and "unbind". Also, the special value "help" can be used to list the possible actions. The default value is "add".

Print a short help text and exit.

Maximum number of seconds to wait for the specified devices or device symlinks being created, initialized, or removed. The default value is "infinity".

Check if systemd-udevd initialized devices. Defaults to true. When false, the command only checks if the specified devices exist. Set false to this setting if there is no udev rules for the specified devices, as the devices will never be considered as initialized in that case. See Initialized Devices section below for more details.

When specified, the command wait for devices being removed instead of created or initialized. If this is specified, --initialized= will be ignored.

When specified, also watches the udev event queue, and wait for all queued events being processed by systemd-udevd.

Print a short help text and exit.

Takes a path to a device node of the device to lock. This switch may be used multiple times (and in combination with --backing=) in order to lock multiple devices. If a partition block device node is specified the containing "whole" block device is automatically determined and used for the lock, as per the specification. If multiple devices are specified, they are deduplicated, sorted by the major/minor of their device nodes and then locked in order.

This switch must be used at least once, to specify at least one device to lock. (Alternatively, use --backing=, see below.)

If a path to a device node is specified, identical to --device=. However, this switch alternatively accepts a path to a regular file or directory, in which case the block device of the file system the file/directory resides on is automatically determined and used as if it was specified with --device=.

Specifies how long to wait at most until all locks can be taken. Takes a value in seconds, or in the usual supported time units, see systemd.time(7). If specified as zero the lock is attempted and if not successful the invocation will immediately fail. If passed as "infinity" (the default) the invocation will wait indefinitely until the lock can be acquired. If the lock cannot be taken in the specified time the specified command will not be executed and the invocation will fail.

Instead of locking the specified devices and executing a command, just print the device paths that would be locked, and execute no command. This command is useful to determine the "whole" block device in case a partition block device is specified. The devices will be sorted by their device node major number as primary ordering key and the minor number as secondary ordering key (i.e. they are shown in the order they'd be locked). Note that the number of lines printed here can be less than the the number of --device= and --backing= switches specified in case these resolve to the same "whole" devices.

Print a short help text and exit.