udevadm

UDEVADM(8)                           udevadm                          UDEVADM(8)



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

       -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)



systemd 246                                                           UDEVADM(8)