UDEVADM(8)

  .SH "NAME" udevadm - udev management tool
  .SH "SYNOPSIS"
    .HP u
      udevadm
         [--debug]
         [--version]
         [--help]

    .HP u
      udevadm info [options] [devpath]

    .HP u
      udevadm trigger [options] [devpath]

    .HP u
      udevadm settle [options]

    .HP u
      udevadm control option

    .HP u
      udevadm monitor [options]

    .HP u
      udevadm test [options] devpath

    .HP u
      udevadm test-builtin [options] command devpath

  .SH "DESCRIPTION"
    .PP 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.

  .SH "OPTIONS"

      .PP -d, --debug

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

          .RE
          .PP -h, --help

              Print a short help text and exit.
          .RE

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

                .PP -q, --query=TYPE

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

                    .RE
                    .PP -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.

                        .RE
                        .PP -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.

                            .RE
                            .PP -r, --root

                                    Print absolute paths in name or symlink query.

                                .RE
                                .PP -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.

                                    .RE
                                    .PP -x, --export

                                            Print output as key/value pairs. Values are enclosed in single quotes.

                                        .RE
                                        .PP -P, --export-prefix=NAME

                                                Add a prefix to the key name of exported values.

                                            .RE
                                            .PP -d, --device-id-of-file=FILE

                                                    Print major/minor numbers of the underlying device, where the file lives on.

                                                .RE
                                                .PP -e, --export-db

                                                        Export the content of the udev database.

                                                    .RE
                                                    .PP -c, --cleanup-db

                                                            Cleanup the udev database.

                                                        .RE
                                                        .PP -h, --help

                                                          Print a short help text and exit.
                                                      .RE

                                                        .SS "udevadm trigger [options] [devpath|file|unit...]"
                                                          .PP Request device events from the kernel. Primarily used to replay events at system coldplug time.
                                                          .PP Takes one or more device specifications as arguments. See the description of info above.

                                                            .PP -v, --verbose

                                                                    Print the list of devices which will be triggered.

                                                                .RE
                                                                .PP -n, --dry-run

                                                                        Do not actually trigger the event.

                                                                    .RE
                                                                    .PP -t, --type=TYPE

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

                                                                        .RE
                                                                        .PP -c, --action=ACTION

                                                                                Type of event to be triggered. The default value is change.

                                                                            .RE
                                                                            .PP -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.

                                                                                .RE
                                                                                .PP -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.

                                                                                    .RE
                                                                                    .PP -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.

                                                                                        .RE
                                                                                        .PP -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.

                                                                                            .RE
                                                                                            .PP -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.

                                                                                                .RE
                                                                                                .PP -g, --tag-match=PROPERTY

                                                                                                        Trigger events for devices with a matching tag. This option can be specified multiple times.

                                                                                                    .RE
                                                                                                    .PP -y, --sysname-match=PATH

                                                                                                            Trigger events for devices for which the last component (i.e. the filename) of the /sys path matches the specified PATH. This option can be specified multiple times and also supports shell style pattern matching.

                                                                                                        .RE
                                                                                                        .PP --name-match=NAME

                                                                                                                Trigger events for devices with a matching device path. This option can be specified multiple times.

                                                                                                            .RE
                                                                                                            .PP -b, --parent-match=SYSPATH

                                                                                                                    Trigger events for all children of a given device.

                                                                                                                .RE
                                                                                                                .PP -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.

                                                                                                                    .RE
                                                                                                                    .PP -h, --help

                                                                                                                      Print a short help text and exit.
                                                                                                                  .RE

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

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

                                                                                                                        .PP -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.

                                                                                                                            .RE
                                                                                                                            .PP -E, --exit-if-exists=FILE

                                                                                                                                    Stop waiting if file exists.

                                                                                                                                .RE
                                                                                                                                .PP -h, --help

                                                                                                                                  Print a short help text and exit.
                                                                                                                              .RE

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

                                                                                                                                    .PP -e, --exit

                                                                                                                                        Signal and wait for systemd-udevd to exit.

                                                                                                                                    .RE
                                                                                                                                    .PP -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.

                                                                                                                                    .RE
                                                                                                                                    .PP -s, --stop-exec-queue

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

                                                                                                                                    .RE
                                                                                                                                    .PP -S, --start-exec-queue

                                                                                                                                        Signal systemd-udevd to enable the execution of events.

                                                                                                                                    .RE
                                                                                                                                    .PP -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.

                                                                                                                                    .RE
                                                                                                                                    .PP -p, --property=KEY=value

                                                                                                                                        Set a global property for all events.

                                                                                                                                    .RE
                                                                                                                                    .PP -m, --children-max=value

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

                                                                                                                                    .RE
                                                                                                                                    .PP -t, --timeout=seconds

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

                                                                                                                                    .RE
                                                                                                                                    .PP -h, --help

                                                                                                                                  Print a short help text and exit.
                                                                                                                              .RE

                                                                                                                                .SS "udevadm monitor [options]"
                                                                                                                                  .PP 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.

                                                                                                                                    .PP -k, --kernel

                                                                                                                                        Print the kernel uevents.

                                                                                                                                    .RE
                                                                                                                                    .PP -u, --udev

                                                                                                                                        Print the udev event after the rule processing.

                                                                                                                                    .RE
                                                                                                                                    .PP -p, --property

                                                                                                                                        Also print the properties of the event.

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

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

                                                                                                                                    .RE
                                                                                                                                    .PP -t, --tag-match=string

                                                                                                                                        Filter udev events by tag. Only udev events with a given tag attached will pass.

                                                                                                                                    .RE
                                                                                                                                    .PP -h, --help

                                                                                                                                  Print a short help text and exit.
                                                                                                                              .RE

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

                                                                                                                                    .PP -a, --action=string

                                                                                                                                        The action string.

                                                                                                                                    .RE
                                                                                                                                    .PP -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.

                                                                                                                                    .RE
                                                                                                                                    .PP -h, --help

                                                                                                                                  Print a short help text and exit.
                                                                                                                              .RE

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

                                                                                                                                    .PP -h, --help

                                                                                                                                  Print a short help text and exit.
                                                                                                                              .RE

                                                                                                                              .SH "SEE ALSO"

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