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 hwdb [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 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 /sys path of the device to query, e.g.  [/sys]/class/block/sda. Note that this option usually isn't 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.

       --name=file
	   The name of the device node or a symlink to query, e.g.  [/dev]/sda. Note that this option usually isn't very useful, since udev can
	   guess the type of the argument, so udevadm --name=sda is equivalent to udevadm /dev/sda.

       --root
	   Print absolute paths in name or symlink query.

       --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 systemd-udevd to exit.

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

       --stop-exec-queue
	   Signal systemd-udevd to stop executing new events. Incoming events will be queued.

       --start-exec-queue
	   Signal systemd-udevd to enable the execution of events.

       --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.

       --property=KEY=value
	   Set a global property for all events.

       --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.

       --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 hwdb [options]
       Maintain the hardware database index in /etc/udev/hwdb.bin.

       --update
	   Compile the hardware database information located in /usr/lib/udev/hwdb.d/, /etc/udev/hwdb.d/ and store it in /etc/udev/hwdb.bin. This
	   should be done after any update to the source files; it will not be called automatically. The running udev daemon will detect a new
	   database on its own and does not need to be notified about it.

       --test=string
	   Query the database with a modalias string, and print the retrieved properties.

       --root=string
	   Alternative root path in the file system for reading and writing files.

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

       --action=string
	   The action string.

       --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.

       --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.

SEE ALSO

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

systemd 208																UDEVADM(8)