systemd udevadm 8 udevadmudev management tool udevadm --debug --version --help udevadm info options devpath udevadm trigger options devpath udevadm settle options udevadm control option udevadm monitor options udevadm test options devpath udevadm test-builtin options command devpath 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. -d --debug Print debug messages to standard error. This option is implied in udevadm test and udevadm test-builtin commands. 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.device5). -q --query=TYPE Query the database for the specified type of device data. Valid TYPEs are: name, symlink, path, property, all. --property=NAME When showing device properties using the --query=property option, limit display to properties specified in the argument. The argument should be a comma-separated list of property names. If not specified, all known properties are shown. --value When showing device properties using the --query=property option, print only their values, and skip the property name and =. Cannot be used together with -x/--export or -P/--export-prefix. -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. udevadm info --path=/class/block/sda is equivalent to udevadm info /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. udevadm info --name=sda is equivalent to udevadm info /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. -wSECONDS --wait-for-initialization=SECONDS Wait for device to be initialized. If argument SECONDS is not specified, the default is to wait forever. The generated output shows the current device database entry in a terse format. Each line shown is prefixed with one of the following characters: Prefix Meaning P: Device path in /sys/ N: Kernel device node name L: Device node symlink priority S: Device node symlink E: Device property 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. -q --quiet Suppress error logging in triggering events. -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. Also, the special value help can be used to list the possible actions. 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=TAG 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 udevadm settle. udevadm settle waits for all events to finish. This option only waits for events triggered by the same command to finish. --uuid Trigger the synthetic device events, and associate a randomized UUID with each. These UUIDs are printed to standard output, one line for each event. These UUIDs are included in the uevent environment block (in the SYNTH_UUID= property) and may be used to track delivery of the generated events. --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 udevadm control --ping before udevadm trigger. In addition, optional positional arguments can be used to specify device names or sys paths. They must start with /dev/ or /sys/ respectively. 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. A non-zero value will return an exit code of 0 if queue became empty before timeout was reached, non-zero otherwise. -E --exit-if-exists=FILE Stop waiting if file exists. See systemd-udev-settle.service8 for more information. 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: systemctl stop systemd-udevd-control.socket systemd-udevd-kernel.socket systemd-udevd.service -l --log-level=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. 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. Simulate a udev event run for the given device, and print debug output. -a --action=ACTION Type of event to be simulated. Possible actions are add, remove, change, move, online, offline, bind, and unbind. Also, the special value help can be used to list the possible actions. The default value is add. -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. Run a built-in command COMMAND for device DEVPATH, and print debug output. -a --action=ACTION Type of event to be simulated. Possible actions are add, remove, change, move, online, offline, bind, and unbind. Also, the special value help can be used to list the possible actions. The default value is add. udev7 , systemd-udevd.service8