1UDEVADM(8) udevadm UDEVADM(8)
2
6 udevadm - udev management tool
7
9 udevadm [--debug] [--version] [--help]
10 udevadm info [options] [devpath]
12 udevadm trigger [options] [devpath]
14 udevadm settle [options]
16 udevadm control option
18 udevadm monitor [options]
20 udevadm test [options] devpath
22 udevadm test-builtin [options] command devpath
24
26 udevadm expects a command and command specific options. It controls the
27 runtime behavior of systemd-udevd, requests kernel events, manages the
28 event queue, and provides simple debugging mechanisms.
29
31 -d, --debug
32 Print debug messages to standard error. This option is implied in
33 udevadm test and udevadm test-builtin commands.
34 -h, --help
36 Print a short help text and exit.
37 udevadm info [options] [devpath|file|unit...]
39 Query the udev database for device information.
40 Positional arguments should be used to specify one or more devices.
42 Each one may be a device name (in which case it must start with /dev/),
43 a sys path (in which case it must start with /sys/), or a systemd
44 device unit name (in which case it must end with ".device", see
45 systemd.device(5)).
46 -q, --query=TYPE
48 Query the database for the specified type of device data. Valid
49 TYPEs are: name, symlink, path, property, all.
50 --property=NAME
52 When showing device properties using the --query=property option,
53 limit display to properties specified in the argument. The argument
54 should be a comma-separated list of property names. If not
55 specified, all known properties are shown.
56 --value
58 When showing device properties using the --query=property option,
59 print only their values, and skip the property name and "=".
60 Cannot be used together with -x/--export or -P/--export-prefix.
62 -p, --path=DEVPATH
64 The /sys/ path of the device to query, e.g.
65 [/sys/]/class/block/sda. This option is an alternative to the
66 positional argument with a /sys/ prefix. udevadm info
67 --path=/class/block/sda is equivalent to udevadm info
68 /sys/class/block/sda.
69 -n, --name=FILE
71 The name of the device node or a symlink to query, e.g.
72 [/dev/]/sda. This option is an alternative to the positional
73 argument with a /dev/ prefix. udevadm info --name=sda is
74 equivalent to udevadm info /dev/sda.
75 -r, --root
77 Print absolute paths in name or symlink query.
78 -a, --attribute-walk
80 Print all sysfs properties of the specified device that can be used
81 in udev rules to match the specified device. It prints all devices
82 along the chain, up to the root of sysfs that can be used in udev
83 rules.
84 -x, --export
86 Print output as key/value pairs. Values are enclosed in single
87 quotes. This takes effects only when --query=property or
88 --device-id-of-file=FILE is specified.
89 -P, --export-prefix=NAME
91 Add a prefix to the key name of exported values. This implies
92 --export.
93 -d, --device-id-of-file=FILE
95 Print major/minor numbers of the underlying device, where the file
96 lives on. If this is specified, all positional arguments are
97 ignored.
98 -e, --export-db
100 Export the content of the udev database.
101 -c, --cleanup-db
103 Cleanup the udev database.
104 -w[SECONDS], --wait-for-initialization[=SECONDS]
106 Wait for device to be initialized. If argument SECONDS is not
107 specified, the default is to wait forever.
108 -h, --help
110 Print a short help text and exit.
111 The generated output shows the current device database entry in a terse
113 format. Each line shown is prefixed with one of the following
114 characters:
115 Table 1. udevadm info output prefixes
117 ┌───────┬─────────────────────────┐
118 │Prefix │ Meaning │
119 ├───────┼─────────────────────────┤
120 │"P:" │ Device path in /sys/ │
121 ├───────┼─────────────────────────┤
122 │"N:" │ Kernel device node name │
123 ├───────┼─────────────────────────┤
124 │"L:" │ Device node symlink │
125 │ │ priority │
126 ├───────┼─────────────────────────┤
127 │"S:" │ Device node symlink │
128 ├───────┼─────────────────────────┤
129 │"E:" │ Device property │
130 └───────┴─────────────────────────┘
131 udevadm trigger [options] [devpath|file|unit]
133 Request device events from the kernel. Primarily used to replay events
134 at system coldplug time.
135 Takes device specifications as positional arguments. See the
137 description of info above.
138 -v, --verbose
140 Print the list of devices which will be triggered.
141 -n, --dry-run
143 Do not actually trigger the event.
144 -q, --quiet
146 Suppress error logging in triggering events.
147 -t, --type=TYPE
149 Trigger a specific type of devices. Valid types are: devices,
150 subsystems. The default value is devices.
151 -c, --action=ACTION
153 Type of event to be triggered. Possible actions are "add",
154 "remove", "change", "move", "online", "offline", "bind", and
155 "unbind". Also, the special value "help" can be used to list the
156 possible actions. The default value is "change".
157 -s, --subsystem-match=SUBSYSTEM
159 Trigger events for devices which belong to a matching subsystem.
160 This option supports shell style pattern matching. When this option
161 is specified more than once, then each matching result is ORed,
162 that is, all the devices in each subsystem are triggered.
163 -S, --subsystem-nomatch=SUBSYSTEM
165 Do not trigger events for devices which belong to a matching
166 subsystem. This option supports shell style pattern matching. When
167 this option is specified more than once, then each matching result
168 is ANDed, that is, devices which do not match all specified
169 subsystems are triggered.
170 -a, --attr-match=ATTRIBUTE=VALUE
172 Trigger events for devices with a matching sysfs attribute. If a
173 value is specified along with the attribute name, the content of
174 the attribute is matched against the given value using shell style
175 pattern matching. If no value is specified, the existence of the
176 sysfs attribute is checked. When this option is specified multiple
177 times, then each matching result is ANDed, that is, only devices
178 which have all specified attributes are triggered.
179 -A, --attr-nomatch=ATTRIBUTE=VALUE
181 Do not trigger events for devices with a matching sysfs attribute.
182 If a value is specified along with the attribute name, the content
183 of the attribute is matched against the given value using shell
184 style pattern matching. If no value is specified, the existence of
185 the sysfs attribute is checked. When this option is specified
186 multiple times, then each matching result is ANDed, that is, only
187 devices which have none of the specified attributes are triggered.
188 -p, --property-match=PROPERTY=VALUE
190 Trigger events for devices with a matching property value. This
191 option supports shell style pattern matching. When this option is
192 specified more than once, then each matching result is ORed, that
193 is, devices which have one of the specified properties are
194 triggered.
195 -g, --tag-match=TAG
197 Trigger events for devices with a matching tag. When this option is
198 specified multiple times, then each matching result is ANDed, that
199 is, devices which have all specified tags are triggered.
200 -y, --sysname-match=NAME
202 Trigger events for devices for which the last component (i.e. the
203 filename) of the /sys/ path matches the specified PATH. This option
204 supports shell style pattern matching. When this option is
205 specified more than once, then each matching result is ORed, that
206 is, all devices which have any of the specified NAME are triggered.
207 --name-match=NAME
209 Trigger events for devices with a matching device path. When this
210 option is specified more than once, then each matching result is
211 ORed, that is, all specified devices are triggered.
212 -b, --parent-match=SYSPATH
214 Trigger events for all children of a given device. When this option
215 is specified more than once, then each matching result is ORed,
216 that is, all children of each specified device are triggered.
217 -w, --settle
219 Apart from triggering events, also waits for those events to
220 finish. Note that this is different from calling udevadm settle.
221 udevadm settle waits for all events to finish. This option only
222 waits for events triggered by the same command to finish.
223 --uuid
225 Trigger the synthetic device events, and associate a randomized
226 UUID with each. These UUIDs are printed to standard output, one
227 line for each event. These UUIDs are included in the uevent
228 environment block (in the "SYNTH_UUID=" property) and may be used
229 to track delivery of the generated events.
230 --wait-daemon[=SECONDS]
232 Before triggering uevents, wait for systemd-udevd daemon to be
233 initialized. Optionally takes timeout value. Default timeout is 5
234 seconds. This is equivalent to invoke invoking udevadm control
235 --ping before udevadm trigger.
236 -h, --help
238 Print a short help text and exit.
239 In addition, optional positional arguments can be used to specify
241 device names or sys paths. They must start with /dev/ or /sys/
242 respectively.
243 udevadm settle [options]
245 Watches the udev event queue, and exits if all current events are
246 handled.
247 -t, --timeout=SECONDS
249 Maximum number of seconds to wait for the event queue to become
250 empty. The default value is 120 seconds. A value of 0 will check if
251 the queue is empty and always return immediately. A non-zero value
252 will return an exit code of 0 if queue became empty before timeout
253 was reached, non-zero otherwise.
254 -E, --exit-if-exists=FILE
256 Stop waiting if file exists.
257 -h, --help
259 Print a short help text and exit.
260 See systemd-udev-settle.service(8) for more information.
262 udevadm control option
264 Modify the internal state of the running udev daemon.
265 -e, --exit
267 Signal and wait for systemd-udevd to exit. No option except for
268 --timeout can be specified after this option. Note that
269 systemd-udevd.service contains Restart=always and so as a result,
270 this option restarts systemd-udevd. If you want to stop
271 systemd-udevd.service, please use the following:
272 systemctl stop systemd-udevd-control.socket systemd-udevd-kernel.socket systemd-udevd.service
274 -l, --log-level=value
277 Set the internal log level of systemd-udevd. Valid values are the
278 numerical syslog priorities or their textual representations:
279 emerg, alert, crit, err, warning, notice, info, and debug.
280 -s, --stop-exec-queue
282 Signal systemd-udevd to stop executing new events. Incoming events
283 will be queued.
284 -S, --start-exec-queue
286 Signal systemd-udevd to enable the execution of events.
287 -R, --reload
289 Signal systemd-udevd to reload the rules files and other databases
290 like the kernel module index. Reloading rules and databases does
291 not apply any changes to already existing devices; the new
292 configuration will only be applied to new events.
293 -p, --property=KEY=value
295 Set a global property for all events.
296 -m, --children-max=value
298 Set the maximum number of events, systemd-udevd will handle at the
299 same time.
300 --ping
302 Send a ping message to systemd-udevd and wait for the reply. This
303 may be useful to check that systemd-udevd daemon is running.
304 -t, --timeout=seconds
306 The maximum number of seconds to wait for a reply from
307 systemd-udevd.
308 -h, --help
310 Print a short help text and exit.
311 udevadm monitor [options]
313 Listens to the kernel uevents and events sent out by a udev rule and
314 prints the devpath of the event to the console. It can be used to
315 analyze the event timing, by comparing the timestamps of the kernel
316 uevent and the udev event.
317 -k, --kernel
319 Print the kernel uevents.
320 -u, --udev
322 Print the udev event after the rule processing.
323 -p, --property
325 Also print the properties of the event.
326 -s, --subsystem-match=string[/string]
328 Filter kernel uevents and udev events by subsystem[/devtype]. Only
329 events with a matching subsystem value will pass. When this option
330 is specified more than once, then each matching result is ORed,
331 that is, all devices in the specified subsystems are monitored.
332 -t, --tag-match=string
334 Filter udev events by tag. Only udev events with a given tag
335 attached will pass. When this option is specified more than once,
336 then each matching result is ORed, that is, devices which have one
337 of the specified tags are monitored.
338 -h, --help
340 Print a short help text and exit.
341 udevadm test [options] [devpath]
343 Simulate a udev event run for the given device, and print debug output.
344 -a, --action=ACTION
346 Type of event to be simulated. Possible actions are "add",
347 "remove", "change", "move", "online", "offline", "bind", and
348 "unbind". Also, the special value "help" can be used to list the
349 possible actions. The default value is "add".
350 -N, --resolve-names=early|late|never
352 Specify when udevadm should resolve names of users and groups. When
353 set to early (the default), names will be resolved when the rules
354 are parsed. When set to late, names will be resolved for every
355 event. When set to never, names will never be resolved and all
356 devices will be owned by root.
357 -h, --help
359 Print a short help text and exit.
360 udevadm test-builtin [options] [command] [devpath]
362 Run a built-in command COMMAND for device DEVPATH, and print debug
363 output.
364 -a, --action=ACTION
366 Type of event to be simulated. Possible actions are "add",
367 "remove", "change", "move", "online", "offline", "bind", and
368 "unbind". Also, the special value "help" can be used to list the
369 possible actions. The default value is "add".
370 -h, --help
372 Print a short help text and exit.
373
375 udev(7), systemd-udevd.service(8)
376systemd 250 UDEVADM(8)