udevadm

udev management tool

SYNOPSIS

' udevadm 'u udevadm [ --debug ][ --version ][ --help ] ' udevadminfo [options] [devpath] 'u udevadminfo [options] [devpath] ' udevadmtrigger [options] [devpath] 'u udevadmtrigger [options] [devpath] ' udevadmsettle [options] 'u udevadmsettle [options] ' udevadmcontrol option 'u udevadmcontrol option ' udevadmmonitor [options] 'u udevadmmonitor [options] ' udevadmtest [options] devpath 'u udevadmtest [options] devpath ' udevadmtest -builtin [options] command devpath 'u udevadmtest -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

-d , --debug Print debug messages to standard error . This option is implied in udevadmtest and udevadmtest -builtin commands .

-h , --help Print a short help text and exit .

"udevadm info [ options ][ devpath | file | unit ...]"



Query the udev database for device information .

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)).

-q , --query= TYPE Query the database for the specified type of device data . Valid TYPE sare: name , symlink , path , property , all .

-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 . udevadminfo --path=/class/block/sda is equivalent to udevadminfo /sys/class/block/sda .

-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 . udevadminfo --name=sda is equivalent to udevadminfo /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 . This takes effects only when --query=property or --device -id -of -file= FILE is specified .

-P , --export -prefix= NAME Add a prefix to the key name of exported values . This implies --export .

-d , --device -id -of -file= FILE Print major/minor numbers of the underlying device, where the file lives on . If this is specified, all positional arguments are ignored .

-e , --export -db Export the content of the udev database .

-c , --cleanup -db Cleanup the udev database .

-h , --help Print a short help text and exit .

"udevadm trigger [ options ][ devpath | file | unit ]"



Request device events from the kernel . Primarily used to replay events at system coldplug time .

Takes device specifications as positional arguments . See the description of info above .

-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 . Possible actions are "add", "remove", "change", "move", "online", "offline", "bind", and unbind. The default value is change.

-s , --subsystem -match= SUBSYSTEM Trigger events for devices which belong to a matching subsystem . This option supports shell style pattern matching . When this option is specified more than once, then each matching result is ORed, that is, all the devices in each subsystem are triggered .

-S , --subsystem -nomatch= SUBSYSTEM Do not trigger events for devices which belong to a matching subsystem . This option supports shell style pattern matching . When this option is specified more than once, then each matching result is ANDed, that is, devices which do not match all specified subsystems are triggered .

-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 . When this option is specified multiple times, then each matching result is ANDed, that is, only devices which have all specified attributes are triggered .

-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 . When this option is specified multiple times, then each matching result is ANDed, that is, only devices which have none of the specified attributes are triggered .

-p , --property -match= PROPERTY = VALUE Trigger events for devices with a matching property value . This option supports shell style pattern matching . When this option is specified more than once, then each matching result is ORed, that is, devices which have one of the specified properties are triggered .

-g , --tag -match= PROPERTY Trigger events for devices with a matching tag . When this option is specified multiple times, then each matching result is ANDed, that is, devices which have all specified tags are triggered .

-y , --sysname -match= NAME Trigger events for devices for which the last component (i .e . the filename) of the /sys path matches the specified PATH . This option supports shell style pattern matching . When this option is specified more than once, then each matching result is ORed, that is, all devices which have any of the specified NAME are triggered .

--name -match= NAME Trigger events for devices with a matching device path . When this option is specified more than once, then each matching result is ORed, that is, all specified devices are triggered .

-b , --parent -match= SYSPATH Trigger events for all children of a given device . When this option is specified more than once, then each matching result is ORed, that is, all children of each specified device are triggered .

-w , --settle Apart from triggering events, also waits for those events to finish . Note that this is different from calling udevadmsettle . udevadmsettle waits for all events to finish . This option only waits for events triggered by the same command to finish .

--wait -daemon[= SECONDS ] Before triggering uevents, wait for systemd -udevd daemon to be initialized . Optionally takes timeout value . Default timeout is 5 seconds . This is equivalent to invoke invoking udevadmcontrol --ping before udevadmtrigger .

-h , --help Print a short help text and exit .

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 a short help text and exit .

"udevadm control option "



Modify the internal state of the running udev daemon .

-e , --exit Signal and wait for systemd -udevd to exit . No option except for --timeout can be specified after this option . Note that systemd -udevd .service contains Restart=always and so as a result, this option restarts systemd -udevd . If you want to stop systemd -udevd .service, please use the following:
.RS 4
systemctl stop systemd -udevd -control .socket systemd -udevd -kernel .socket systemd -udevd .service .RE


-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 .

--ping Send a ping message to systemd -udevd and wait for the reply . This may be useful to check that systemd -udevd daemon is running .

-t , --timeout= seconds The maximum number of seconds to wait for a reply from systemd -udevd .

-h , --help Print a short help text and exit .

"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 kernel uevents and udev events by subsystem[/devtype] . Only events with a matching subsystem value will pass . When this option is specified more than once, then each matching result is ORed, that is, all devices in the specified subsystems are monitored .

-t , --tag -match= string Filter udev events by tag . Only udev events with a given tag attached will pass . When this option is specified more than once, then each matching result is ORed, that is, devices which have one of the specified tags are monitored .

-h , --help Print a short help text and exit .

"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 a short help text and exit .

"udevadm test -builtin [ options ][ command ][ devpath ]"



Run a built -in command COMMAND for device DEVPATH ,and print debug output .

-h , --help Print a short help text and exit .

SEE ALSO

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

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