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3802a3d3 | 1 | <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*--> |
63749b1a | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
7b86ada7 | 4 | |
f48f7543 ZJS |
5 | <!-- |
6 | SPDX-License-Identifier: LGPL-2.1+ | |
7 | ||
f48f7543 ZJS |
8 | Copyright 2012 Kay Sievers |
9 | Copyright 2014 Jason St. John | |
f48f7543 ZJS |
10 | --> |
11 | ||
63749b1a KS |
12 | <refentry id="udev"> |
13 | <refentryinfo> | |
7b86ada7 | 14 | <title>udev</title> |
d3a2386d KS |
15 | <productname>systemd</productname> |
16 | <authorgroup> | |
17 | <author> | |
18 | <contrib>Developer</contrib> | |
19 | <firstname>Greg</firstname> | |
20 | <surname>Kroah-Hartmann</surname> | |
21 | <email>greg@kroah.com</email> | |
22 | </author> | |
23 | <author> | |
24 | <contrib>Developer</contrib> | |
25 | <firstname>Kay</firstname> | |
26 | <surname>Sievers</surname> | |
27 | <email>kay@vrfy.org</email> | |
28 | </author> | |
29 | </authorgroup> | |
63749b1a KS |
30 | </refentryinfo> |
31 | ||
32 | <refmeta> | |
33 | <refentrytitle>udev</refentrytitle> | |
34 | <manvolnum>7</manvolnum> | |
35 | </refmeta> | |
36 | ||
37 | <refnamediv> | |
38 | <refname>udev</refname> | |
eb75d0ed | 39 | <refpurpose>Dynamic device management</refpurpose> |
63749b1a KS |
40 | </refnamediv> |
41 | ||
42 | <refsect1><title>Description</title> | |
43 | <para>udev supplies the system software with device events, manages permissions | |
44 | of device nodes and may create additional symlinks in the <filename>/dev</filename> | |
45 | directory, or renames network interfaces. The kernel usually just assigns unpredictable | |
46 | device names based on the order of discovery. Meaningful symlinks or network device | |
47 | names provide a way to reliably identify devices based on their properties or | |
48 | current configuration.</para> | |
49 | ||
b79f817b | 50 | <para>The udev daemon, <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle> |
0e4fa2ab | 51 | <manvolnum>8</manvolnum></citerefentry>, receives device uevents directly from |
63749b1a KS |
52 | the kernel whenever a device is added or removed from the system, or it changes its |
53 | state. When udev receives a device event, it matches its configured set of rules | |
0e846301 MW |
54 | against various device attributes to identify the device. Rules that match may |
55 | provide additional device information to be stored in the udev database or | |
63749b1a KS |
56 | to be used to create meaningful symlink names.</para> |
57 | ||
0e846301 | 58 | <para>All device information udev processes is stored in the udev database and |
63749b1a | 59 | sent out to possible event subscribers. Access to all stored data and the event |
17fd0f60 | 60 | sources is provided by the library libudev.</para> |
63749b1a KS |
61 | </refsect1> |
62 | ||
eb75d0ed | 63 | <refsect1><title>Rules Files</title> |
63749b1a | 64 | <para>The udev rules are read from the files located in the |
12b42c76 | 65 | system rules directory <filename>/usr/lib/udev/rules.d</filename>, |
91418155 KS |
66 | the volatile runtime directory <filename>/run/udev/rules.d</filename> |
67 | and the local administration directory <filename>/etc/udev/rules.d</filename>. | |
1021e6df KS |
68 | All rules files are collectively sorted and processed in lexical order, |
69 | regardless of the directories in which they live. However, files with | |
e9dd9f95 | 70 | identical filenames replace each other. Files in <filename>/etc</filename> |
91418155 | 71 | have the highest priority, files in <filename>/run</filename> take precedence |
12b42c76 | 72 | over files with the same name in <filename>/usr/lib</filename>. This can be |
91418155 KS |
73 | used to override a system-supplied rules file with a local file if needed; |
74 | a symlink in <filename>/etc</filename> with the same name as a rules file in | |
12b42c76 | 75 | <filename>/usr/lib</filename>, pointing to <filename>/dev/null</filename>, |
eb75d0ed KS |
76 | disables the rules file entirely. Rule files must have the extension |
77 | <filename>.rules</filename>; other extensions are ignored.</para> | |
63749b1a | 78 | |
feedf8f3 | 79 | <para>Every line in the rules file contains at least one key-value pair. |
909f413d | 80 | Except for empty lines or lines beginning with <literal>#</literal>, which are ignored. |
bb31a4ac | 81 | There are two kinds of keys: match and assignment. |
6ec0ac43 TG |
82 | If all match keys match against their values, the rule gets applied and the |
83 | assignment keys get the specified values assigned.</para> | |
63749b1a KS |
84 | |
85 | <para>A matching rule may rename a network interface, add symlinks | |
86 | pointing to the device node, or run a specified program as part of | |
87 | the event handling.</para> | |
88 | ||
55f5037c MW |
89 | <para>A rule consists of a comma-separated list of one or more key-value pairs. |
90 | Each key has a distinct operation, depending on the used operator. Valid | |
63749b1a KS |
91 | operators are:</para> |
92 | <variablelist> | |
93 | <varlistentry> | |
6b76fa66 | 94 | <term><literal>==</literal></term> |
63749b1a KS |
95 | <listitem> |
96 | <para>Compare for equality.</para> | |
97 | </listitem> | |
98 | </varlistentry> | |
99 | ||
100 | <varlistentry> | |
6b76fa66 | 101 | <term><literal>!=</literal></term> |
63749b1a KS |
102 | <listitem> |
103 | <para>Compare for inequality.</para> | |
104 | </listitem> | |
105 | </varlistentry> | |
106 | ||
107 | <varlistentry> | |
6b76fa66 | 108 | <term><literal>=</literal></term> |
63749b1a | 109 | <listitem> |
0e846301 | 110 | <para>Assign a value to a key. Keys that represent a list are reset |
63749b1a KS |
111 | and only this single value is assigned.</para> |
112 | </listitem> | |
113 | </varlistentry> | |
114 | ||
115 | <varlistentry> | |
6b76fa66 | 116 | <term><literal>+=</literal></term> |
63749b1a KS |
117 | <listitem> |
118 | <para>Add the value to a key that holds a list of entries.</para> | |
119 | </listitem> | |
120 | </varlistentry> | |
121 | ||
8e3ba377 DH |
122 | <varlistentry> |
123 | <term><literal>-=</literal></term> | |
124 | <listitem> | |
125 | <para>Remove the value from a key that holds a list of entries.</para> | |
126 | </listitem> | |
127 | </varlistentry> | |
128 | ||
63749b1a | 129 | <varlistentry> |
6b76fa66 | 130 | <term><literal>:=</literal></term> |
63749b1a | 131 | <listitem> |
2bf11540 | 132 | <para>Assign a value to a key finally; disallow any later changes.</para> |
63749b1a KS |
133 | </listitem> |
134 | </varlistentry> | |
135 | </variablelist> | |
136 | ||
137 | <para>The following key names can be used to match against device properties. | |
138 | Some of the keys also match against properties of the parent devices in sysfs, | |
139 | not only the device that has generated the event. If multiple keys that match | |
140 | a parent device are specified in a single rule, all these keys must match at | |
141 | one and the same parent device.</para> | |
ccc9a4f9 | 142 | <variablelist class='udev-directives'> |
63749b1a | 143 | <varlistentry> |
909f413d | 144 | <term><varname>ACTION</varname></term> |
63749b1a KS |
145 | <listitem> |
146 | <para>Match the name of the event action.</para> | |
147 | </listitem> | |
148 | </varlistentry> | |
149 | ||
150 | <varlistentry> | |
909f413d | 151 | <term><varname>DEVPATH</varname></term> |
63749b1a KS |
152 | <listitem> |
153 | <para>Match the devpath of the event device.</para> | |
154 | </listitem> | |
155 | </varlistentry> | |
156 | ||
157 | <varlistentry> | |
909f413d | 158 | <term><varname>KERNEL</varname></term> |
63749b1a KS |
159 | <listitem> |
160 | <para>Match the name of the event device.</para> | |
161 | </listitem> | |
162 | </varlistentry> | |
163 | ||
164 | <varlistentry> | |
909f413d | 165 | <term><varname>NAME</varname></term> |
63749b1a | 166 | <listitem> |
220893b3 KS |
167 | <para>Match the name of a network interface. It can be used once the |
168 | NAME key has been set in one of the preceding rules.</para> | |
63749b1a KS |
169 | </listitem> |
170 | </varlistentry> | |
171 | ||
172 | <varlistentry> | |
909f413d | 173 | <term><varname>SYMLINK</varname></term> |
63749b1a KS |
174 | <listitem> |
175 | <para>Match the name of a symlink targeting the node. It can | |
176 | be used once a SYMLINK key has been set in one of the preceding | |
177 | rules. There may be multiple symlinks; only one needs to match. | |
178 | </para> | |
179 | </listitem> | |
180 | </varlistentry> | |
181 | ||
182 | <varlistentry> | |
909f413d | 183 | <term><varname>SUBSYSTEM</varname></term> |
63749b1a KS |
184 | <listitem> |
185 | <para>Match the subsystem of the event device.</para> | |
186 | </listitem> | |
187 | </varlistentry> | |
188 | <varlistentry> | |
909f413d | 189 | <term><varname>DRIVER</varname></term> |
63749b1a | 190 | <listitem> |
2e7f69eb | 191 | <para>Match the driver name of the event device. Only set this key for devices |
63749b1a KS |
192 | which are bound to a driver at the time the event is generated.</para> |
193 | </listitem> | |
194 | </varlistentry> | |
195 | <varlistentry> | |
909f413d | 196 | <term><varname>ATTR{<replaceable>filename</replaceable>}</varname></term> |
63749b1a KS |
197 | <listitem> |
198 | <para>Match sysfs attribute values of the event device. Trailing | |
65e039c2 MW |
199 | whitespace in the attribute values is ignored unless the specified match |
200 | value itself contains trailing whitespace. | |
63749b1a KS |
201 | </para> |
202 | </listitem> | |
f4cf2e5b KS |
203 | <term><varname>SYSCTL{<replaceable>kernel parameter</replaceable>}</varname></term> |
204 | <listitem> | |
205 | <para>Match a kernel parameter value. | |
206 | </para> | |
207 | </listitem> | |
63749b1a KS |
208 | </varlistentry> |
209 | ||
210 | <varlistentry> | |
909f413d | 211 | <term><varname>KERNELS</varname></term> |
63749b1a KS |
212 | <listitem> |
213 | <para>Search the devpath upwards for a matching device name.</para> | |
214 | </listitem> | |
215 | </varlistentry> | |
216 | ||
217 | <varlistentry> | |
909f413d | 218 | <term><varname>SUBSYSTEMS</varname></term> |
63749b1a KS |
219 | <listitem> |
220 | <para>Search the devpath upwards for a matching device subsystem name.</para> | |
221 | </listitem> | |
222 | </varlistentry> | |
223 | ||
224 | <varlistentry> | |
909f413d | 225 | <term><varname>DRIVERS</varname></term> |
63749b1a KS |
226 | <listitem> |
227 | <para>Search the devpath upwards for a matching device driver name.</para> | |
228 | </listitem> | |
229 | </varlistentry> | |
230 | ||
231 | <varlistentry> | |
909f413d | 232 | <term><varname>ATTRS{<replaceable>filename</replaceable>}</varname></term> |
63749b1a KS |
233 | <listitem> |
234 | <para>Search the devpath upwards for a device with matching sysfs attribute values. | |
909f413d | 235 | If multiple <varname>ATTRS</varname> matches are specified, all of them |
65e039c2 MW |
236 | must match on the same device. Trailing whitespace in the attribute values is ignored |
237 | unless the specified match value itself contains trailing whitespace.</para> | |
63749b1a KS |
238 | </listitem> |
239 | </varlistentry> | |
240 | ||
7df0ed83 | 241 | <varlistentry> |
909f413d | 242 | <term><varname>TAGS</varname></term> |
7df0ed83 KS |
243 | <listitem> |
244 | <para>Search the devpath upwards for a device with matching tag.</para> | |
245 | </listitem> | |
246 | </varlistentry> | |
247 | ||
63749b1a | 248 | <varlistentry> |
909f413d | 249 | <term><varname>ENV{<replaceable>key</replaceable>}</varname></term> |
63749b1a KS |
250 | <listitem> |
251 | <para>Match against a device property value.</para> | |
252 | </listitem> | |
253 | </varlistentry> | |
254 | ||
255 | <varlistentry> | |
909f413d | 256 | <term><varname>TAG</varname></term> |
63749b1a KS |
257 | <listitem> |
258 | <para>Match against a device tag.</para> | |
259 | </listitem> | |
260 | </varlistentry> | |
261 | ||
262 | <varlistentry> | |
909f413d | 263 | <term><varname>TEST{<replaceable>octal mode mask</replaceable>}</varname></term> |
63749b1a KS |
264 | <listitem> |
265 | <para>Test the existence of a file. An octal mode mask can be specified | |
266 | if needed.</para> | |
267 | </listitem> | |
268 | </varlistentry> | |
269 | ||
270 | <varlistentry> | |
909f413d | 271 | <term><varname>PROGRAM</varname></term> |
63749b1a | 272 | <listitem> |
2e9820e3 MW |
273 | <para>Execute a program to determine whether there |
274 | is a match; the key is true if the program returns | |
63749b1a | 275 | successfully. The device properties are made available to the |
f131770b | 276 | executed program in the environment. The program's standard output |
bcddd5bf JSJ |
277 | is available in the <varname>RESULT</varname> key.</para> |
278 | <para>This can only be used for very short-running foreground tasks. For details, | |
909f413d | 279 | see <varname>RUN</varname>.</para> |
63749b1a KS |
280 | </listitem> |
281 | </varlistentry> | |
282 | ||
283 | <varlistentry> | |
909f413d | 284 | <term><varname>RESULT</varname></term> |
63749b1a | 285 | <listitem> |
bcddd5bf JSJ |
286 | <para>Match the returned string of the last <varname>PROGRAM</varname> call. |
287 | This key can be used in the same or in any later rule after a | |
288 | <varname>PROGRAM</varname> call.</para> | |
63749b1a KS |
289 | </listitem> |
290 | </varlistentry> | |
291 | </variablelist> | |
292 | ||
bf2e0ece AB |
293 | <para>Most of the fields support shell glob pattern matching and |
294 | alternate patterns. The following special characters are supported:</para> | |
63749b1a KS |
295 | <variablelist> |
296 | <varlistentry> | |
6b76fa66 | 297 | <term><literal>*</literal></term> |
63749b1a | 298 | <listitem> |
954e9c52 | 299 | <para>Matches zero or more characters.</para> |
63749b1a KS |
300 | </listitem> |
301 | </varlistentry> | |
302 | <varlistentry> | |
6b76fa66 | 303 | <term><literal>?</literal></term> |
63749b1a KS |
304 | <listitem> |
305 | <para>Matches any single character.</para> | |
306 | </listitem> | |
307 | </varlistentry> | |
308 | <varlistentry> | |
6b76fa66 | 309 | <term><literal>[]</literal></term> |
63749b1a KS |
310 | <listitem> |
311 | <para>Matches any single character specified within the brackets. For | |
909f413d ZJS |
312 | example, the pattern string <literal>tty[SR]</literal> |
313 | would match either <literal>ttyS</literal> or <literal>ttyR</literal>. | |
314 | Ranges are also supported via the <literal>-</literal> character. | |
bcddd5bf JSJ |
315 | For example, to match on the range of all digits, the pattern |
316 | <literal>[0-9]</literal> could be used. If the first character | |
317 | following the <literal>[</literal> is a <literal>!</literal>, | |
318 | any characters not enclosed are matched.</para> | |
63749b1a KS |
319 | </listitem> |
320 | </varlistentry> | |
bf2e0ece AB |
321 | <varlistentry> |
322 | <term><literal>|</literal></term> | |
323 | <listitem> | |
324 | <para>Separates alternative patterns. For example, the pattern string | |
325 | <literal>abc|x*</literal> would match either <literal>abc</literal> | |
326 | or <literal>x*</literal>.</para> | |
327 | </listitem> | |
328 | </varlistentry> | |
63749b1a KS |
329 | </variablelist> |
330 | ||
331 | <para>The following keys can get values assigned:</para> | |
ccc9a4f9 | 332 | <variablelist class='udev-directives'> |
63749b1a | 333 | <varlistentry> |
909f413d | 334 | <term><varname>NAME</varname></term> |
63749b1a | 335 | <listitem> |
1ff28eae TG |
336 | <para>The name to use for a network interface. See |
337 | <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
338 | for a higher-level mechanism for setting the interface name. | |
339 | The name of a device node cannot be changed by udev, only additional | |
340 | symlinks can be created.</para> | |
63749b1a KS |
341 | </listitem> |
342 | </varlistentry> | |
343 | ||
344 | <varlistentry> | |
909f413d | 345 | <term><varname>SYMLINK</varname></term> |
63749b1a | 346 | <listitem> |
933b5623 | 347 | <para>The name of a symlink targeting the node. Every matching rule adds |
b1239c3f KS |
348 | this value to the list of symlinks to be created.</para> |
349 | <para>The set of characters to name a symlink is limited. Allowed | |
909f413d ZJS |
350 | characters are <literal>0-9A-Za-z#+-.:=@_/</literal>, valid UTF-8 character |
351 | sequences, and <literal>\x00</literal> hex encoding. All other | |
352 | characters are replaced by a <literal>_</literal> character.</para> | |
b1239c3f KS |
353 | <para>Multiple symlinks may be specified by separating the names by the |
354 | space character. In case multiple devices claim the same name, the link | |
355 | always points to the device with the highest link_priority. If the current | |
356 | device goes away, the links are re-evaluated and the device with the | |
357 | next highest link_priority becomes the owner of the link. If no | |
358 | link_priority is specified, the order of the devices (and which one of | |
359 | them owns the link) is undefined.</para> | |
360 | <para>Symlink names must never conflict with the kernel's default device | |
361 | node names, as that would result in unpredictable behavior. | |
63749b1a KS |
362 | </para> |
363 | </listitem> | |
364 | </varlistentry> | |
365 | ||
366 | <varlistentry> | |
909f413d | 367 | <term><varname>OWNER</varname>, <varname>GROUP</varname>, <varname>MODE</varname></term> |
63749b1a | 368 | <listitem> |
91418155 | 369 | <para>The permissions for the device node. Every specified value overrides |
63749b1a KS |
370 | the compiled-in default value.</para> |
371 | </listitem> | |
372 | </varlistentry> | |
373 | ||
c26547d6 KS |
374 | <varlistentry> |
375 | <term><varname>SECLABEL{<replaceable>module</replaceable>}</varname></term> | |
376 | <listitem> | |
377 | <para>Applies the specified Linux Security Module label to the device node.</para> | |
378 | </listitem> | |
379 | </varlistentry> | |
380 | ||
63749b1a | 381 | <varlistentry> |
909f413d | 382 | <term><varname>ATTR{<replaceable>key</replaceable>}</varname></term> |
63749b1a KS |
383 | <listitem> |
384 | <para>The value that should be written to a sysfs attribute of the | |
385 | event device.</para> | |
386 | </listitem> | |
387 | </varlistentry> | |
388 | ||
f4cf2e5b KS |
389 | <varlistentry> |
390 | <term><varname>SYSCTL{<replaceable>kernel parameter</replaceable>}</varname></term> | |
391 | <listitem> | |
392 | <para>The value that should be written to kernel parameter.</para> | |
393 | </listitem> | |
394 | </varlistentry> | |
395 | ||
63749b1a | 396 | <varlistentry> |
909f413d | 397 | <term><varname>ENV{<replaceable>key</replaceable>}</varname></term> |
63749b1a | 398 | <listitem> |
909f413d | 399 | <para>Set a device property value. Property names with a leading <literal>.</literal> |
ed9c5fb7 | 400 | are neither stored in the database nor exported to events or |
bcddd5bf JSJ |
401 | external tools (run by, for example, the <varname>PROGRAM</varname> |
402 | match key).</para> | |
63749b1a KS |
403 | </listitem> |
404 | </varlistentry> | |
405 | ||
406 | <varlistentry> | |
909f413d | 407 | <term><varname>TAG</varname></term> |
63749b1a KS |
408 | <listitem> |
409 | <para>Attach a tag to a device. This is used to filter events for users | |
410 | of libudev's monitor functionality, or to enumerate a group of tagged | |
411 | devices. The implementation can only work efficiently if only a few | |
412 | tags are attached to a device. It is only meant to be used in | |
413 | contexts with specific device filter requirements, and not as a | |
414 | general-purpose flag. Excessive use might result in inefficient event | |
415 | handling.</para> | |
416 | </listitem> | |
417 | </varlistentry> | |
418 | ||
419 | <varlistentry> | |
909f413d | 420 | <term><varname>RUN{<replaceable>type</replaceable>}</varname></term> |
63749b1a | 421 | <listitem> |
bcddd5bf JSJ |
422 | <para>Add a program to the list of programs to be executed after |
423 | processing all the rules for a specific event, depending on | |
424 | <literal>type</literal>:</para> | |
72c6cf8f TG |
425 | <variablelist> |
426 | <varlistentry> | |
427 | <term><literal>program</literal></term> | |
428 | <listitem> | |
429 | <para>Execute an external program specified as the assigned | |
bcddd5bf | 430 | value. If no absolute path is given, the program is expected |
12b42c76 | 431 | to live in <filename>/usr/lib/udev</filename>; otherwise, the |
bcddd5bf JSJ |
432 | absolute path must be specified.</para> |
433 | <para>This is the default if no <replaceable>type</replaceable> | |
434 | is specified.</para> | |
72c6cf8f TG |
435 | </listitem> |
436 | </varlistentry> | |
437 | <varlistentry> | |
438 | <term><literal>builtin</literal></term> | |
439 | <listitem> | |
bcddd5bf JSJ |
440 | <para>As <varname>program</varname>, but use one of the |
441 | built-in programs rather than an external one.</para> | |
72c6cf8f TG |
442 | </listitem> |
443 | </varlistentry> | |
444 | </variablelist> | |
445 | <para>The program name and following arguments are separated by spaces. | |
446 | Single quotes can be used to specify arguments with spaces.</para> | |
b45f770f | 447 | <para>This can only be used for very short-running foreground tasks. Running an |
2b76eb68 | 448 | event process for a long period of time may block all further events for |
b45f770f | 449 | this or a dependent device.</para> |
bcddd5bf | 450 | <para>Starting daemons or other long-running processes is not appropriate |
b45f770f KS |
451 | for udev; the forked processes, detached or not, will be unconditionally |
452 | killed after the event handling has finished.</para> | |
877dce40 MS |
453 | <para>Note that running programs that access the network or mount/unmount |
454 | filesystems is not allowed inside of udev rules, due to the default sandbox | |
455 | that is enforced on <filename>systemd-udevd.service</filename>.</para> | |
63749b1a KS |
456 | </listitem> |
457 | </varlistentry> | |
458 | ||
459 | <varlistentry> | |
909f413d | 460 | <term><varname>LABEL</varname></term> |
63749b1a | 461 | <listitem> |
bcddd5bf | 462 | <para>A named label to which a <varname>GOTO</varname> may jump.</para> |
63749b1a KS |
463 | </listitem> |
464 | </varlistentry> | |
465 | ||
466 | <varlistentry> | |
909f413d | 467 | <term><varname>GOTO</varname></term> |
63749b1a | 468 | <listitem> |
bcddd5bf | 469 | <para>Jumps to the next <varname>LABEL</varname> with a matching name.</para> |
63749b1a KS |
470 | </listitem> |
471 | </varlistentry> | |
472 | ||
473 | <varlistentry> | |
909f413d | 474 | <term><varname>IMPORT{<replaceable>type</replaceable>}</varname></term> |
63749b1a KS |
475 | <listitem> |
476 | <para>Import a set of variables as device properties, | |
6b76fa66 | 477 | depending on <literal>type</literal>:</para> |
63749b1a KS |
478 | <variablelist> |
479 | <varlistentry> | |
6b76fa66 | 480 | <term><literal>program</literal></term> |
63749b1a | 481 | <listitem> |
9de4d0ce | 482 | <para>Execute an external program specified as the assigned |
b938cb90 | 483 | value and, if it returns successfully, |
63749b1a KS |
484 | import its output, which must be in environment key |
485 | format. Path specification, command/argument separation, | |
909f413d | 486 | and quoting work like in <varname>RUN</varname>.</para> |
63749b1a KS |
487 | </listitem> |
488 | </varlistentry> | |
489 | <varlistentry> | |
72c6cf8f TG |
490 | <term><literal>builtin</literal></term> |
491 | <listitem> | |
909f413d ZJS |
492 | <para>Similar to <literal>program</literal>, but use one of the |
493 | built-in programs rather than an external one.</para> | |
72c6cf8f TG |
494 | </listitem> |
495 | </varlistentry> | |
496 | <varlistentry> | |
6b76fa66 | 497 | <term><literal>file</literal></term> |
63749b1a | 498 | <listitem> |
b6a49cd6 MW |
499 | <para>Import a text file specified as the assigned value, the content |
500 | of which must be in environment key format.</para> | |
63749b1a KS |
501 | </listitem> |
502 | </varlistentry> | |
503 | <varlistentry> | |
6b76fa66 | 504 | <term><literal>db</literal></term> |
63749b1a KS |
505 | <listitem> |
506 | <para>Import a single property specified as the assigned value from the | |
507 | current device database. This works only if the database is already populated | |
508 | by an earlier event.</para> | |
509 | </listitem> | |
510 | </varlistentry> | |
c4f6dcc4 | 511 | <varlistentry> |
6b76fa66 | 512 | <term><literal>cmdline</literal></term> |
c4f6dcc4 | 513 | <listitem> |
ad9c70a8 | 514 | <para>Import a single property from the kernel command line. For simple flags |
909f413d | 515 | the value of the property is set to <literal>1</literal>.</para> |
c4f6dcc4 KS |
516 | </listitem> |
517 | </varlistentry> | |
63749b1a | 518 | <varlistentry> |
6b76fa66 | 519 | <term><literal>parent</literal></term> |
63749b1a KS |
520 | <listitem> |
521 | <para>Import the stored keys from the parent device by reading | |
522 | the database entry of the parent device. The value assigned to | |
523 | <option>IMPORT{parent}</option> is used as a filter of key names | |
eb75d0ed | 524 | to import (with the same shell glob pattern matching used for |
63749b1a KS |
525 | comparisons).</para> |
526 | </listitem> | |
527 | </varlistentry> | |
528 | </variablelist> | |
b45f770f KS |
529 | <para>This can only be used for very short-running foreground tasks. For details |
530 | see <option>RUN</option>.</para> | |
63749b1a KS |
531 | </listitem> |
532 | </varlistentry> | |
533 | ||
63749b1a | 534 | <varlistentry> |
909f413d | 535 | <term><varname>OPTIONS</varname></term> |
63749b1a KS |
536 | <listitem> |
537 | <para>Rule and device options:</para> | |
ccc9a4f9 | 538 | <variablelist class='udev-directives'> |
63749b1a KS |
539 | <varlistentry> |
540 | <term><option>link_priority=<replaceable>value</replaceable></option></term> | |
541 | <listitem> | |
542 | <para>Specify the priority of the created symlinks. Devices with higher | |
543 | priorities overwrite existing symlinks of other devices. The default is 0.</para> | |
544 | </listitem> | |
545 | </varlistentry> | |
63749b1a KS |
546 | <varlistentry> |
547 | <term><option>string_escape=<replaceable>none|replace</replaceable></option></term> | |
548 | <listitem> | |
b938cb90 | 549 | <para>Usually, control and other possibly unsafe characters are replaced |
63749b1a KS |
550 | in strings used for device naming. The mode of replacement can be specified |
551 | with this option.</para> | |
552 | </listitem> | |
553 | </varlistentry> | |
9fa68615 KS |
554 | <varlistentry> |
555 | <term><option>static_node=</option></term> | |
556 | <listitem> | |
bcddd5bf JSJ |
557 | <para>Apply the permissions specified in this rule to the |
558 | static device node with the specified name. Also, for every | |
559 | tag specified in this rule, create a symlink | |
84b6ad70 TG |
560 | in the directory |
561 | <filename>/run/udev/static_node-tags/<replaceable>tag</replaceable></filename> | |
bcddd5bf JSJ |
562 | pointing at the static device node with the specified name. |
563 | Static device node creation is performed by systemd-tmpfiles | |
564 | before systemd-udevd is started. The static nodes might not | |
565 | have a corresponding kernel device; they are used to trigger | |
566 | automatic kernel module loading when they are accessed.</para> | |
9fa68615 KS |
567 | </listitem> |
568 | </varlistentry> | |
63749b1a KS |
569 | <varlistentry> |
570 | <term><option>watch</option></term> | |
571 | <listitem> | |
bcddd5bf JSJ |
572 | <para>Watch the device node with inotify; when the node is |
573 | closed after being opened for writing, a change uevent is | |
574 | synthesized.</para> | |
63749b1a KS |
575 | </listitem> |
576 | </varlistentry> | |
3b529da4 KS |
577 | <varlistentry> |
578 | <term><option>nowatch</option></term> | |
579 | <listitem> | |
580 | <para>Disable the watching of a device node with inotify.</para> | |
581 | </listitem> | |
582 | </varlistentry> | |
63749b1a KS |
583 | </variablelist> |
584 | </listitem> | |
585 | </varlistentry> | |
586 | </variablelist> | |
587 | ||
bcddd5bf JSJ |
588 | <para>The <varname>NAME</varname>, <varname>SYMLINK</varname>, |
589 | <varname>PROGRAM</varname>, <varname>OWNER</varname>, | |
4f985bd8 MS |
590 | <varname>GROUP</varname>, <varname>MODE</varname>, <varname>SECLABEL</varname>, |
591 | and <varname>RUN</varname> fields support simple string substitutions. | |
bcddd5bf JSJ |
592 | The <varname>RUN</varname> substitutions are performed after all rules |
593 | have been processed, right before the program is executed, allowing for | |
594 | the use of device properties set by earlier matching rules. For all other | |
595 | fields, substitutions are performed while the individual rule is being | |
596 | processed. The available substitutions are:</para> | |
ccc9a4f9 | 597 | <variablelist class='udev-directives'> |
63749b1a KS |
598 | <varlistentry> |
599 | <term><option>$kernel</option>, <option>%k</option></term> | |
600 | <listitem> | |
601 | <para>The kernel name for this device.</para> | |
602 | </listitem> | |
603 | </varlistentry> | |
604 | ||
605 | <varlistentry> | |
606 | <term><option>$number</option>, <option>%n</option></term> | |
607 | <listitem> | |
909f413d | 608 | <para>The kernel number for this device. For example, |
bcddd5bf JSJ |
609 | <literal>sda3</literal> has kernel number <literal>3</literal>. |
610 | </para> | |
63749b1a KS |
611 | </listitem> |
612 | </varlistentry> | |
613 | ||
614 | <varlistentry> | |
615 | <term><option>$devpath</option>, <option>%p</option></term> | |
616 | <listitem> | |
617 | <para>The devpath of the device.</para> | |
618 | </listitem> | |
619 | </varlistentry> | |
620 | ||
621 | <varlistentry> | |
622 | <term><option>$id</option>, <option>%b</option></term> | |
623 | <listitem> | |
bcddd5bf JSJ |
624 | <para>The name of the device matched while searching the devpath |
625 | upwards for <option>SUBSYSTEMS</option>, <option>KERNELS</option>, | |
626 | <option>DRIVERS</option>, and <option>ATTRS</option>. | |
63749b1a KS |
627 | </para> |
628 | </listitem> | |
629 | </varlistentry> | |
630 | ||
631 | <varlistentry> | |
632 | <term><option>$driver</option></term> | |
633 | <listitem> | |
bcddd5bf JSJ |
634 | <para>The driver name of the device matched while searching the |
635 | devpath upwards for <option>SUBSYSTEMS</option>, | |
636 | <option>KERNELS</option>, <option>DRIVERS</option>, and | |
637 | <option>ATTRS</option>. | |
63749b1a KS |
638 | </para> |
639 | </listitem> | |
640 | </varlistentry> | |
641 | ||
642 | <varlistentry> | |
643 | <term><option>$attr{<replaceable>file</replaceable>}</option>, <option>%s{<replaceable>file</replaceable>}</option></term> | |
644 | <listitem> | |
0e846301 | 645 | <para>The value of a sysfs attribute found at the device where |
bcddd5bf JSJ |
646 | all keys of the rule have matched. If the matching device does not |
647 | have such an attribute, and a previous <option>KERNELS</option>, | |
648 | <option>SUBSYSTEMS</option>, <option>DRIVERS</option>, or | |
649 | <option>ATTRS</option> test selected a parent device, then the | |
650 | attribute from that parent device is used. | |
651 | </para> | |
652 | <para>If the attribute is a symlink, the last element of the | |
653 | symlink target is returned as the value. | |
654 | </para> | |
63749b1a KS |
655 | </listitem> |
656 | </varlistentry> | |
657 | ||
658 | <varlistentry> | |
659 | <term><option>$env{<replaceable>key</replaceable>}</option>, <option>%E{<replaceable>key</replaceable>}</option></term> | |
660 | <listitem> | |
661 | <para>A device property value.</para> | |
662 | </listitem> | |
663 | </varlistentry> | |
664 | ||
665 | <varlistentry> | |
666 | <term><option>$major</option>, <option>%M</option></term> | |
667 | <listitem> | |
668 | <para>The kernel major number for the device.</para> | |
669 | </listitem> | |
670 | </varlistentry> | |
671 | ||
672 | <varlistentry> | |
673 | <term><option>$minor</option>, <option>%m</option></term> | |
674 | <listitem> | |
675 | <para>The kernel minor number for the device.</para> | |
676 | </listitem> | |
677 | </varlistentry> | |
678 | ||
679 | <varlistentry> | |
680 | <term><option>$result</option>, <option>%c</option></term> | |
681 | <listitem> | |
bcddd5bf JSJ |
682 | <para>The string returned by the external program requested with |
683 | <varname>PROGRAM</varname>. | |
21188522 | 684 | A single part of the string, separated by a space character, may be selected |
909f413d ZJS |
685 | by specifying the part number as an attribute: <literal>%c{N}</literal>. |
686 | If the number is followed by the <literal>+</literal> character, this part plus all remaining parts | |
687 | of the result string are substituted: <literal>%c{N+}</literal>.</para> | |
63749b1a KS |
688 | </listitem> |
689 | </varlistentry> | |
690 | ||
691 | <varlistentry> | |
692 | <term><option>$parent</option>, <option>%P</option></term> | |
693 | <listitem> | |
694 | <para>The node name of the parent device.</para> | |
695 | </listitem> | |
696 | </varlistentry> | |
697 | ||
698 | <varlistentry> | |
699 | <term><option>$name</option></term> | |
700 | <listitem> | |
220893b3 | 701 | <para>The current name of the device. If not changed by a rule, it is the |
63749b1a KS |
702 | name of the kernel device.</para> |
703 | </listitem> | |
704 | </varlistentry> | |
705 | ||
706 | <varlistentry> | |
707 | <term><option>$links</option></term> | |
708 | <listitem> | |
e8b5e4e5 | 709 | <para>A space-separated list of the current symlinks. The value is |
2d74bc75 | 710 | only set during a remove event or if an earlier rule assigned a value.</para> |
63749b1a KS |
711 | </listitem> |
712 | </varlistentry> | |
713 | ||
714 | <varlistentry> | |
715 | <term><option>$root</option>, <option>%r</option></term> | |
716 | <listitem> | |
717 | <para>The udev_root value.</para> | |
718 | </listitem> | |
719 | </varlistentry> | |
720 | ||
721 | <varlistentry> | |
722 | <term><option>$sys</option>, <option>%S</option></term> | |
723 | <listitem> | |
724 | <para>The sysfs mount point.</para> | |
725 | </listitem> | |
726 | </varlistentry> | |
727 | ||
728 | <varlistentry> | |
220893b3 | 729 | <term><option>$devnode</option>, <option>%N</option></term> |
63749b1a | 730 | <listitem> |
220893b3 | 731 | <para>The name of the device node.</para> |
63749b1a KS |
732 | </listitem> |
733 | </varlistentry> | |
734 | ||
735 | <varlistentry> | |
909f413d | 736 | <term><option>%%</option></term> |
63749b1a | 737 | <listitem> |
909f413d | 738 | <para>The <literal>%</literal> character itself.</para> |
63749b1a KS |
739 | </listitem> |
740 | </varlistentry> | |
741 | ||
742 | <varlistentry> | |
909f413d | 743 | <term><option>$$</option></term> |
63749b1a | 744 | <listitem> |
909f413d | 745 | <para>The <literal>$</literal> character itself.</para> |
63749b1a KS |
746 | </listitem> |
747 | </varlistentry> | |
748 | </variablelist> | |
63749b1a KS |
749 | </refsect1> |
750 | ||
63749b1a KS |
751 | <refsect1> |
752 | <title>See Also</title> | |
bcddd5bf JSJ |
753 | <para> |
754 | <citerefentry> | |
b79f817b | 755 | <refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum> |
ad29a9f1 | 756 | </citerefentry>, |
63749b1a KS |
757 | <citerefentry> |
758 | <refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum> | |
2b09983f | 759 | </citerefentry>, |
1ff28eae TG |
760 | <citerefentry> |
761 | <refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum> | |
762 | </citerefentry> | |
bcddd5bf | 763 | </para> |
63749b1a KS |
764 | </refsect1> |
765 | </refentry> |