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.
-e, --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)
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