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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.
-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 options 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)
systemd 219 UDEVADM(8)
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Under GNU General Public License
2024-11-23 18:23 @127.0.0.1 CrawledBy Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)