udevadm <root
UDEVADM(8)                                   udevadm                                   UDEVADM(8)

NAME
       udevadm - udev management tool

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

       udevadm info options

       udevadm trigger [options]

       udevadm settle [options]

       udevadm control command

       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
       --debug
           Print debug messages to standard error.

       --version
           Print version number.

       -h, --help
           Print help text.

   udevadm info [options] [devpath|file]
       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.

       -q, --query=TYPE
           Query the database for the specified type of device data. It needs the --path or
           --name to identify the specified device. 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. Note that this
           option usually is not very useful, since udev can guess the type of the argument, so
           udevadm --devpath=/class/block/sda is equivalent to udevadm /sys/class/block/sda.

       -n, --name=FILE
           The name of the device node or a symlink to query, e.g.  [/dev]/sda. Note that this
           option usually is not very useful, since udev can guess the type of the argument, so
           udevadm --name=sda is equivalent to udevadm /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.

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

       -d, --device-id-of-file=FILE
           Print major/minor numbers of the underlying device, where the file lives on.

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

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

       --version
           Print version.

       -h, --help
           Print help text.

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

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

       -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. The default value is change.

       -s, --subsystem-match=SUBSYSTEM
           Trigger events for devices which belong to a matching subsystem. This option can be
           specified multiple times and supports shell style pattern matching.

       -S, --subsystem-nomatch=SUBSYSTEM
           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.

       -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. This option can be specified multiple
           times.

       -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. This option can be specified multiple
           times.

       -p, --property-match=PROPERTY=VALUE
           Trigger events for devices with a matching property value. This option can be
           specified multiple times and supports shell style pattern matching.

       -g, --tag-match=PROPERTY
           Trigger events for devices with a matching tag. This option can be specified multiple
           times.

       -y, --sysname-match=PATH
           Trigger events for devices with a matching sys device path. This option can be
           specified multiple times and supports shell style pattern matching.

       --name-match=NAME
           Trigger events for devices with a matching device path. This option can be specified
           multiple times.

       -b, --parent-match=SYSPATH
           Trigger events for all children of a given device.

       -h, --help
           Print help text.

       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 help text.

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

       -x, --exit
           Signal and wait for systemd-udevd to exit.

       -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.

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

       -h, --help
           Print help text.

   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 events by subsystem[/devtype]. Only udev events with a matching subsystem value
           will pass.

       -t, --tag-match=string
           Filter events by property. Only udev events with a given tag attached will pass.

       -h, --help
           Print help text.

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

       -a, --action=string
           The action string.

       -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 help text.

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

       -h, --help
           Print help text.

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

systemd 229                                                                            UDEVADM(8)

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