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
-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.
-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]
-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 219 UDEVADM(8)
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