NAME

       udevadm - udev management tool

SYNOPSIS

       udevadm [--debug] [--version] [--help]

       udevadm info [options] [devpath]

       udevadm trigger [options] [devpath]

       udevadm settle [options]

       udevadm control option

       udevadm monitor [options]

       udevadm test [options] devpath

       udevadm test-builtin [options] command devpath

DESCRIPTION

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

OPTIONS

       -d, --debug
           Print debug messages to standard error. This option is implied in udevadm test and
           udevadm test-builtin commands.

       -h, --help
           Print a short help text and exit.

   udevadm info [options] [devpath|file|unit...]
       Query the udev database for device information.

       Positional arguments should be used to specify one or more devices. Each one may be a
       device name (in which case it must start with /dev/), a sys path (in which case it must
       start with /sys/), or a systemd device unit name (in which case it must end with
       ".device", see systemd.device(5)).

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

       -p, --path=DEVPATH
           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.

       -n, --name=FILE
           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.

       -r, --root
           Print absolute paths in name or symlink query.

       -a, --attribute-walk
           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.

       -x, --export
           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.

       -P, --export-prefix=NAME
           Add a prefix to the key name of exported values. This implies --export.

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

       -e, --export-db
           Export the content of the udev database.

       -c, --cleanup-db
           Cleanup the udev database.

       -w[SECONDS], --wait-for-initialization[=SECONDS]
           Wait for device to be initialized. If argument SECONDS is not specified, the default
           is to wait forever.

       -h, --help
           Print a short help text and exit.

   udevadm trigger [options] [devpath|file|unit]
       Request device events from the kernel. Primarily used to replay events at system coldplug
       time.

       Takes device specifications as positional arguments. See the description of info above.

       -v, --verbose
           Print the list of devices which will be triggered.

       -n, --dry-run
           Do not actually trigger the event.

       -t, --type=TYPE
           Trigger a specific type of devices. Valid types are: devices, subsystems. The default
           value is devices.

       -c, --action=ACTION
           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".

       -s, --subsystem-match=SUBSYSTEM
           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.

       -S, --subsystem-nomatch=SUBSYSTEM
           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.

       -a, --attr-match=ATTRIBUTE=VALUE
           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.

       -A, --attr-nomatch=ATTRIBUTE=VALUE
           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.

       -p, --property-match=PROPERTY=VALUE
           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.

       -g, --tag-match=PROPERTY
           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.

       -y, --sysname-match=NAME
           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.

       --name-match=NAME
           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.

       -b, --parent-match=SYSPATH
           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.

       -w, --settle
           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.

       --wait-daemon[=SECONDS]
           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.

       -h, --help
           Print a short help text and exit.

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

   udevadm settle [options]
       Watches the udev event queue, and exits if all current events are handled.

       -t, --timeout=SECONDS
           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.

       -E, --exit-if-exists=FILE
           Stop waiting if file exists.

       -h, --help
           Print a short help text and exit.

       See systemd-udev-settle.service(8) for more information.

   udevadm control option
       Modify the internal state of the running udev daemon.

       -e, --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

       -l, --log-priority=value
           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.

       -s, --stop-exec-queue
           Signal systemd-udevd to stop executing new events. Incoming events will be queued.

       -S, --start-exec-queue
           Signal systemd-udevd to enable the execution of events.

       -R, --reload
           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.

       -p, --property=KEY=value
           Set a global property for all events.

       -m, --children-max=value
           Set the maximum number of events, systemd-udevd will handle at the same time.

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

       -t, --timeout=seconds
           The maximum number of seconds to wait for a reply from systemd-udevd.

       -h, --help
           Print a short help text and exit.

   udevadm monitor [options]
       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.

       -k, --kernel
           Print the kernel uevents.

       -u, --udev
           Print the udev event after the rule processing.

       -p, --property
           Also print the properties of the event.

       -s, --subsystem-match=string[/string]
           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.

       -t, --tag-match=string
           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.

       -h, --help
           Print a short help text and exit.

   udevadm test [options] [devpath]
       Simulate a udev event run for the given device, and print debug output.

       -a, --action=ACTION
           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".

       -N, --resolve-names=early|late|never
           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.

       -h, --help
           Print a short help text and exit.

   udevadm test-builtin [options] [command] [devpath]
       Run a built-in command COMMAND for device DEVPATH, and print debug output.

       -h, --help
           Print a short help text and exit.

SEE ALSO

       udev(7), systemd-udevd.service(8)