1UDEVADM(8)                          udevadm                         UDEVADM(8)
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NAME

6       udevadm - udev management tool
7

SYNOPSIS

9       udevadm [--debug] [--version] [--help]
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11       udevadm info [options] [devpath]
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13       udevadm trigger [options] [devpath]
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15       udevadm settle [options]
16
17       udevadm control option
18
19       udevadm monitor [options]
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21       udevadm test [options] devpath
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23       udevadm test-builtin [options] command devpath
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DESCRIPTION

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

OPTIONS

31       -d, --debug
32           Print debug messages to standard error. This option is implied in
33           udevadm test and udevadm test-builtin commands.
34
35       -h, --help
36           Print a short help text and exit.
37
38   udevadm info [options] [devpath|file|unit...]
39       Query the udev database for device information.
40
41       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
47       -q, --query=TYPE
48           Query the database for the specified type of device data. Valid
49           TYPEs are: name, symlink, path, property, all.
50
51       -p, --path=DEVPATH
52           The /sys/ path of the device to query, e.g.
53           [/sys/]/class/block/sda. This option is an alternative to the
54           positional argument with a /sys/ prefix.  udevadm info
55           --path=/class/block/sda is equivalent to udevadm info
56           /sys/class/block/sda.
57
58       -n, --name=FILE
59           The name of the device node or a symlink to query, e.g.
60           [/dev/]/sda. This option is an alternative to the positional
61           argument with a /dev/ prefix.  udevadm info --name=sda is
62           equivalent to udevadm info /dev/sda.
63
64       -r, --root
65           Print absolute paths in name or symlink query.
66
67       -a, --attribute-walk
68           Print all sysfs properties of the specified device that can be used
69           in udev rules to match the specified device. It prints all devices
70           along the chain, up to the root of sysfs that can be used in udev
71           rules.
72
73       -x, --export
74           Print output as key/value pairs. Values are enclosed in single
75           quotes. This takes effects only when --query=property or
76           --device-id-of-file=FILE is specified.
77
78       -P, --export-prefix=NAME
79           Add a prefix to the key name of exported values. This implies
80           --export.
81
82       -d, --device-id-of-file=FILE
83           Print major/minor numbers of the underlying device, where the file
84           lives on. If this is specified, all positional arguments are
85           ignored.
86
87       -e, --export-db
88           Export the content of the udev database.
89
90       -c, --cleanup-db
91           Cleanup the udev database.
92
93       -w[SECONDS], --wait-for-initialization[=SECONDS]
94           Wait for device to be initialized. If argument SECONDS is not
95           specified, the default is to wait forever.
96
97       -h, --help
98           Print a short help text and exit.
99
100       The generated output shows the current device database entry in a terse
101       format. Each line shown is prefixed with one of the following
102       characters:
103
104       Table 1. udevadm info output prefixes
105       ┌───────┬─────────────────────────┐
106Prefix Meaning                 
107       ├───────┼─────────────────────────┤
108       │"P:"   │ Device path in /sys/    │
109       ├───────┼─────────────────────────┤
110       │"N:"   │ Kernel device node name │
111       ├───────┼─────────────────────────┤
112       │"L:"   │ Device node symlink     │
113       │       │ priority                │
114       ├───────┼─────────────────────────┤
115       │"S:"   │ Device node symlink     │
116       ├───────┼─────────────────────────┤
117       │"E:"   │ Device property         │
118       └───────┴─────────────────────────┘
119
120   udevadm trigger [options] [devpath|file|unit]
121       Request device events from the kernel. Primarily used to replay events
122       at system coldplug time.
123
124       Takes device specifications as positional arguments. See the
125       description of info above.
126
127       -v, --verbose
128           Print the list of devices which will be triggered.
129
130       -n, --dry-run
131           Do not actually trigger the event.
132
133       -q, --quiet
134           Suppress error logging in triggering events.
135
136       -t, --type=TYPE
137           Trigger a specific type of devices. Valid types are: devices,
138           subsystems. The default value is devices.
139
140       -c, --action=ACTION
141           Type of event to be triggered. Possible actions are "add",
142           "remove", "change", "move", "online", "offline", "bind", and
143           "unbind". Also, the special value "help" can be used to list the
144           possible actions. The default value is "change".
145
146       -s, --subsystem-match=SUBSYSTEM
147           Trigger events for devices which belong to a matching subsystem.
148           This option supports shell style pattern matching. When this option
149           is specified more than once, then each matching result is ORed,
150           that is, all the devices in each subsystem are triggered.
151
152       -S, --subsystem-nomatch=SUBSYSTEM
153           Do not trigger events for devices which belong to a matching
154           subsystem. This option supports shell style pattern matching. When
155           this option is specified more than once, then each matching result
156           is ANDed, that is, devices which do not match all specified
157           subsystems are triggered.
158
159       -a, --attr-match=ATTRIBUTE=VALUE
160           Trigger events for devices with a matching sysfs attribute. If a
161           value is specified along with the attribute name, the content of
162           the attribute is matched against the given value using shell style
163           pattern matching. If no value is specified, the existence of the
164           sysfs attribute is checked. When this option is specified multiple
165           times, then each matching result is ANDed, that is, only devices
166           which have all specified attributes are triggered.
167
168       -A, --attr-nomatch=ATTRIBUTE=VALUE
169           Do not trigger events for devices with a matching sysfs attribute.
170           If a value is specified along with the attribute name, the content
171           of the attribute is matched against the given value using shell
172           style pattern matching. If no value is specified, the existence of
173           the sysfs attribute is checked. When this option is specified
174           multiple times, then each matching result is ANDed, that is, only
175           devices which have none of the specified attributes are triggered.
176
177       -p, --property-match=PROPERTY=VALUE
178           Trigger events for devices with a matching property value. This
179           option supports shell style pattern matching. When this option is
180           specified more than once, then each matching result is ORed, that
181           is, devices which have one of the specified properties are
182           triggered.
183
184       -g, --tag-match=TAG
185           Trigger events for devices with a matching tag. When this option is
186           specified multiple times, then each matching result is ANDed, that
187           is, devices which have all specified tags are triggered.
188
189       -y, --sysname-match=NAME
190           Trigger events for devices for which the last component (i.e. the
191           filename) of the /sys/ path matches the specified PATH. This option
192           supports shell style pattern matching. When this option is
193           specified more than once, then each matching result is ORed, that
194           is, all devices which have any of the specified NAME are triggered.
195
196       --name-match=NAME
197           Trigger events for devices with a matching device path. When this
198           option is specified more than once, then each matching result is
199           ORed, that is, all specified devices are triggered.
200
201       -b, --parent-match=SYSPATH
202           Trigger events for all children of a given device. When this option
203           is specified more than once, then each matching result is ORed,
204           that is, all children of each specified device are triggered.
205
206       -w, --settle
207           Apart from triggering events, also waits for those events to
208           finish. Note that this is different from calling udevadm settle.
209           udevadm settle waits for all events to finish. This option only
210           waits for events triggered by the same command to finish.
211
212       --uuid
213           Trigger the synthetic device events, and associate a randomized
214           UUID with each. These UUIDs are printed to standard output, one
215           line for each event. These UUIDs are included in the uevent
216           environment block (in the "SYNTH_UUID=" property) and may be used
217           to track delivery of the generated events.
218
219       --wait-daemon[=SECONDS]
220           Before triggering uevents, wait for systemd-udevd daemon to be
221           initialized. Optionally takes timeout value. Default timeout is 5
222           seconds. This is equivalent to invoke invoking udevadm control
223           --ping before udevadm trigger.
224
225       -h, --help
226           Print a short help text and exit.
227
228       In addition, optional positional arguments can be used to specify
229       device names or sys paths. They must start with /dev/ or /sys/
230       respectively.
231
232   udevadm settle [options]
233       Watches the udev event queue, and exits if all current events are
234       handled.
235
236       -t, --timeout=SECONDS
237           Maximum number of seconds to wait for the event queue to become
238           empty. The default value is 120 seconds. A value of 0 will check if
239           the queue is empty and always return immediately. A non-zero value
240           will return an exit code of 0 if queue became empty before timeout
241           was reached, non-zero otherwise.
242
243       -E, --exit-if-exists=FILE
244           Stop waiting if file exists.
245
246       -h, --help
247           Print a short help text and exit.
248
249       See systemd-udev-settle.service(8) for more information.
250
251   udevadm control option
252       Modify the internal state of the running udev daemon.
253
254       -e, --exit
255           Signal and wait for systemd-udevd to exit. No option except for
256           --timeout can be specified after this option. Note that
257           systemd-udevd.service contains Restart=always and so as a result,
258           this option restarts systemd-udevd. If you want to stop
259           systemd-udevd.service, please use the following:
260
261               systemctl stop systemd-udevd-control.socket systemd-udevd-kernel.socket systemd-udevd.service
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263
264       -l, --log-level=value
265           Set the internal log level of systemd-udevd. Valid values are the
266           numerical syslog priorities or their textual representations:
267           emerg, alert, crit, err, warning, notice, info, and debug.
268
269       -s, --stop-exec-queue
270           Signal systemd-udevd to stop executing new events. Incoming events
271           will be queued.
272
273       -S, --start-exec-queue
274           Signal systemd-udevd to enable the execution of events.
275
276       -R, --reload
277           Signal systemd-udevd to reload the rules files and other databases
278           like the kernel module index. Reloading rules and databases does
279           not apply any changes to already existing devices; the new
280           configuration will only be applied to new events.
281
282       -p, --property=KEY=value
283           Set a global property for all events.
284
285       -m, --children-max=value
286           Set the maximum number of events, systemd-udevd will handle at the
287           same time.
288
289       --ping
290           Send a ping message to systemd-udevd and wait for the reply. This
291           may be useful to check that systemd-udevd daemon is running.
292
293       -t, --timeout=seconds
294           The maximum number of seconds to wait for a reply from
295           systemd-udevd.
296
297       -h, --help
298           Print a short help text and exit.
299
300   udevadm monitor [options]
301       Listens to the kernel uevents and events sent out by a udev rule and
302       prints the devpath of the event to the console. It can be used to
303       analyze the event timing, by comparing the timestamps of the kernel
304       uevent and the udev event.
305
306       -k, --kernel
307           Print the kernel uevents.
308
309       -u, --udev
310           Print the udev event after the rule processing.
311
312       -p, --property
313           Also print the properties of the event.
314
315       -s, --subsystem-match=string[/string]
316           Filter kernel uevents and udev events by subsystem[/devtype]. Only
317           events with a matching subsystem value will pass. When this option
318           is specified more than once, then each matching result is ORed,
319           that is, all devices in the specified subsystems are monitored.
320
321       -t, --tag-match=string
322           Filter udev events by tag. Only udev events with a given tag
323           attached will pass. When this option is specified more than once,
324           then each matching result is ORed, that is, devices which have one
325           of the specified tags are monitored.
326
327       -h, --help
328           Print a short help text and exit.
329
330   udevadm test [options] [devpath]
331       Simulate a udev event run for the given device, and print debug output.
332
333       -a, --action=ACTION
334           Type of event to be simulated. Possible actions are "add",
335           "remove", "change", "move", "online", "offline", "bind", and
336           "unbind". Also, the special value "help" can be used to list the
337           possible actions. The default value is "add".
338
339       -N, --resolve-names=early|late|never
340           Specify when udevadm should resolve names of users and groups. When
341           set to early (the default), names will be resolved when the rules
342           are parsed. When set to late, names will be resolved for every
343           event. When set to never, names will never be resolved and all
344           devices will be owned by root.
345
346       -h, --help
347           Print a short help text and exit.
348
349   udevadm test-builtin [options] [command] [devpath]
350       Run a built-in command COMMAND for device DEVPATH, and print debug
351       output.
352
353       -h, --help
354           Print a short help text and exit.
355

SEE ALSO

357       udev(7), systemd-udevd.service(8)
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361systemd 249                                                         UDEVADM(8)
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