Linux Commands Examples

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udevadm

udev management tool


see also : udevd

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


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examples

3
source
            
/sbin/udevadm info $*
2
source
            
service autofs restart
udevadm control --reload_rules
udevadm trigger
1
source
            
touch /etc/auto.usb
service autofs restart
udevadm control --reload_rules
udevadm trigger
1
source
            
service udev reload
udevadm trigger
1
source
            
/sbin/udevadm trigger
/sbin/udevadm settle
exit 0
0
source
            
if [ "$1" = "configure" ]; then
udevadm trigger
fi
exit 0

description

udevadm expects a command and command specific options. It controls the runtime behavior of udev, requests kernel events, manages the event queue, and provides simple debugging mechanisms.

options

--debug

Print debug messages to stderr.

--version

Print version number.

--help

Print help text.

udevadm info options
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.

--query=type

Query the database for specified type of device data. It needs the --path or --name to identify the specified device. Valid queries are: name, symlink, path, property, all.

--path=devpath

The devpath of the device to query.

--name=file

The name of the device node or a symlink to query

--root

The udev root directory: /dev. If used in conjunction with a name or symlink query, the query returns the absolute path including the root directory.

--run

The udev runtime directory: /run/udev.

--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.

--export

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

--export-prefix=name

Add a prefix to the key name of exported values.

--device-id-of-file=file

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

--export-db

Export the content of the udev database.

--cleanup-db

Cleanup the udev database.

--version

Print version.

--help

Print help text.

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

--verbose

Print the list of devices which will be triggered.

--dry-run

Do not actually trigger the event.

--type=type

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

--action=action

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

--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.

--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.

--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.

--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.

--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.

--tag-match=property

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

--sysname-match=name

Trigger events for devices with a matching sys device name. This option can be specified multiple times and supports shell style pattern matching.

--parent-match=syspath

Trigger events for all children of a given device.

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

--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.

--seq-start=seqnum

Wait only for events after the given sequence number.

--seq-end=seqnum

Wait only for events before the given sequence number.

--exit-if-exists=file

Stop waiting if file exists.

--quiet

Do not print any output, like the remaining queue entries when reaching the timeout.

--help

Print help text.

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

--exit

Signal and wait for udevd to exit.

--log-priority=value

Set the internal log level of udevd. Valid values are the numerical syslog priorities or their textual representations: err, info and debug.

--stop-exec-queue

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

--start-exec-queue

Signal udevd to enable the execution of events.

--reload-rules

Signal udevd to reload the rules files. The udev daemon detects changes automatically, this option is usually not needed. Reloading rules does not apply any changes to already existing devices.

--property=KEY=value

Set a global property for all events.

--children-max=value

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

--timeout=seconds

The maximum number seonds to wait for a reply from udevd.

--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.

--kernel

Print the kernel uevents.

--udev

Print the udev event after the rule processing.

--property

Also print the properties of the event.

--subsystem-match=string[/string]

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

--tag-match=string

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

--help

Print help text.

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

--action=string

The action string.

--subsystem=string

The subsystem string.

--help

Print help text.

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

--help

Print help text.

udevadm settle

[options]
see also

udev udevd


author

Written by Kay Sievers kay.sievers[:at:]vrfy[:dot:]org.

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