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514094f9 | 1 | <?xml version='1.0'?> |
3a54a157 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//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+ | |
96b2fb93 | 7 | Copyright © 2014 Jason St. John |
f48f7543 ZJS |
8 | --> |
9 | ||
63749b1a KS |
10 | <refentry id="udev"> |
11 | <refentryinfo> | |
7b86ada7 | 12 | <title>udev</title> |
d3a2386d | 13 | <productname>systemd</productname> |
63749b1a KS |
14 | </refentryinfo> |
15 | ||
16 | <refmeta> | |
17 | <refentrytitle>udev</refentrytitle> | |
18 | <manvolnum>7</manvolnum> | |
19 | </refmeta> | |
20 | ||
21 | <refnamediv> | |
22 | <refname>udev</refname> | |
eb75d0ed | 23 | <refpurpose>Dynamic device management</refpurpose> |
63749b1a KS |
24 | </refnamediv> |
25 | ||
26 | <refsect1><title>Description</title> | |
27 | <para>udev supplies the system software with device events, manages permissions | |
28 | of device nodes and may create additional symlinks in the <filename>/dev</filename> | |
29 | directory, or renames network interfaces. The kernel usually just assigns unpredictable | |
30 | device names based on the order of discovery. Meaningful symlinks or network device | |
31 | names provide a way to reliably identify devices based on their properties or | |
32 | current configuration.</para> | |
33 | ||
b79f817b | 34 | <para>The udev daemon, <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle> |
0e4fa2ab | 35 | <manvolnum>8</manvolnum></citerefentry>, receives device uevents directly from |
63749b1a KS |
36 | the kernel whenever a device is added or removed from the system, or it changes its |
37 | state. When udev receives a device event, it matches its configured set of rules | |
0e846301 MW |
38 | against various device attributes to identify the device. Rules that match may |
39 | provide additional device information to be stored in the udev database or | |
63749b1a KS |
40 | to be used to create meaningful symlink names.</para> |
41 | ||
0e846301 | 42 | <para>All device information udev processes is stored in the udev database and |
63749b1a | 43 | sent out to possible event subscribers. Access to all stored data and the event |
17fd0f60 | 44 | sources is provided by the library libudev.</para> |
63749b1a KS |
45 | </refsect1> |
46 | ||
eb75d0ed | 47 | <refsect1><title>Rules Files</title> |
116b91e8 ZJS |
48 | <para>The udev rules are read from the files located in the system rules directories |
49 | <filename>/usr/lib/udev/rules.d</filename> and <filename>/usr/local/lib/udev/rules.d</filename>, the | |
50 | volatile runtime directory <filename>/run/udev/rules.d</filename> and the local administration | |
51 | directory <filename>/etc/udev/rules.d</filename>. All rules files are collectively sorted and | |
52 | processed in lexical order, regardless of the directories in which they live. However, files with | |
53 | identical filenames replace each other. Files in <filename>/etc</filename> have the highest priority, | |
54 | files in <filename>/run</filename> take precedence over files with the same name under | |
55 | <filename>/usr</filename>. This can be used to override a system-supplied rules file with a local | |
56 | file if needed; a symlink in <filename>/etc</filename> with the same name as a rules file in | |
57 | <filename>/usr/lib</filename>, pointing to <filename>/dev/null</filename>, disables the rules file | |
58 | entirely. Rule files must have the extension <filename>.rules</filename>; other extensions are | |
59 | ignored.</para> | |
63749b1a | 60 | |
feedf8f3 | 61 | <para>Every line in the rules file contains at least one key-value pair. |
909f413d | 62 | Except for empty lines or lines beginning with <literal>#</literal>, which are ignored. |
bb31a4ac | 63 | There are two kinds of keys: match and assignment. |
6ec0ac43 TG |
64 | If all match keys match against their values, the rule gets applied and the |
65 | assignment keys get the specified values assigned.</para> | |
63749b1a KS |
66 | |
67 | <para>A matching rule may rename a network interface, add symlinks | |
68 | pointing to the device node, or run a specified program as part of | |
69 | the event handling.</para> | |
70 | ||
55f5037c MW |
71 | <para>A rule consists of a comma-separated list of one or more key-value pairs. |
72 | Each key has a distinct operation, depending on the used operator. Valid | |
63749b1a KS |
73 | operators are:</para> |
74 | <variablelist> | |
75 | <varlistentry> | |
6b76fa66 | 76 | <term><literal>==</literal></term> |
63749b1a KS |
77 | <listitem> |
78 | <para>Compare for equality.</para> | |
79 | </listitem> | |
80 | </varlistentry> | |
81 | ||
82 | <varlistentry> | |
6b76fa66 | 83 | <term><literal>!=</literal></term> |
63749b1a KS |
84 | <listitem> |
85 | <para>Compare for inequality.</para> | |
86 | </listitem> | |
87 | </varlistentry> | |
88 | ||
89 | <varlistentry> | |
6b76fa66 | 90 | <term><literal>=</literal></term> |
63749b1a | 91 | <listitem> |
0e846301 | 92 | <para>Assign a value to a key. Keys that represent a list are reset |
63749b1a KS |
93 | and only this single value is assigned.</para> |
94 | </listitem> | |
95 | </varlistentry> | |
96 | ||
97 | <varlistentry> | |
6b76fa66 | 98 | <term><literal>+=</literal></term> |
63749b1a KS |
99 | <listitem> |
100 | <para>Add the value to a key that holds a list of entries.</para> | |
101 | </listitem> | |
102 | </varlistentry> | |
103 | ||
8e3ba377 DH |
104 | <varlistentry> |
105 | <term><literal>-=</literal></term> | |
106 | <listitem> | |
107 | <para>Remove the value from a key that holds a list of entries.</para> | |
108 | </listitem> | |
109 | </varlistentry> | |
110 | ||
63749b1a | 111 | <varlistentry> |
6b76fa66 | 112 | <term><literal>:=</literal></term> |
63749b1a | 113 | <listitem> |
2bf11540 | 114 | <para>Assign a value to a key finally; disallow any later changes.</para> |
63749b1a KS |
115 | </listitem> |
116 | </varlistentry> | |
117 | </variablelist> | |
118 | ||
119 | <para>The following key names can be used to match against device properties. | |
120 | Some of the keys also match against properties of the parent devices in sysfs, | |
121 | not only the device that has generated the event. If multiple keys that match | |
122 | a parent device are specified in a single rule, all these keys must match at | |
123 | one and the same parent device.</para> | |
ccc9a4f9 | 124 | <variablelist class='udev-directives'> |
63749b1a | 125 | <varlistentry> |
909f413d | 126 | <term><varname>ACTION</varname></term> |
63749b1a KS |
127 | <listitem> |
128 | <para>Match the name of the event action.</para> | |
129 | </listitem> | |
130 | </varlistentry> | |
131 | ||
132 | <varlistentry> | |
909f413d | 133 | <term><varname>DEVPATH</varname></term> |
63749b1a KS |
134 | <listitem> |
135 | <para>Match the devpath of the event device.</para> | |
136 | </listitem> | |
137 | </varlistentry> | |
138 | ||
139 | <varlistentry> | |
909f413d | 140 | <term><varname>KERNEL</varname></term> |
63749b1a KS |
141 | <listitem> |
142 | <para>Match the name of the event device.</para> | |
143 | </listitem> | |
144 | </varlistentry> | |
145 | ||
146 | <varlistentry> | |
909f413d | 147 | <term><varname>NAME</varname></term> |
63749b1a | 148 | <listitem> |
220893b3 KS |
149 | <para>Match the name of a network interface. It can be used once the |
150 | NAME key has been set in one of the preceding rules.</para> | |
63749b1a KS |
151 | </listitem> |
152 | </varlistentry> | |
153 | ||
154 | <varlistentry> | |
909f413d | 155 | <term><varname>SYMLINK</varname></term> |
63749b1a KS |
156 | <listitem> |
157 | <para>Match the name of a symlink targeting the node. It can | |
158 | be used once a SYMLINK key has been set in one of the preceding | |
159 | rules. There may be multiple symlinks; only one needs to match. | |
160 | </para> | |
161 | </listitem> | |
162 | </varlistentry> | |
163 | ||
164 | <varlistentry> | |
909f413d | 165 | <term><varname>SUBSYSTEM</varname></term> |
63749b1a KS |
166 | <listitem> |
167 | <para>Match the subsystem of the event device.</para> | |
168 | </listitem> | |
169 | </varlistentry> | |
170 | <varlistentry> | |
909f413d | 171 | <term><varname>DRIVER</varname></term> |
63749b1a | 172 | <listitem> |
2e7f69eb | 173 | <para>Match the driver name of the event device. Only set this key for devices |
63749b1a KS |
174 | which are bound to a driver at the time the event is generated.</para> |
175 | </listitem> | |
176 | </varlistentry> | |
177 | <varlistentry> | |
909f413d | 178 | <term><varname>ATTR{<replaceable>filename</replaceable>}</varname></term> |
63749b1a KS |
179 | <listitem> |
180 | <para>Match sysfs attribute values of the event device. Trailing | |
65e039c2 MW |
181 | whitespace in the attribute values is ignored unless the specified match |
182 | value itself contains trailing whitespace. | |
63749b1a KS |
183 | </para> |
184 | </listitem> | |
b87613ec DKG |
185 | </varlistentry> |
186 | <varlistentry> | |
f4cf2e5b KS |
187 | <term><varname>SYSCTL{<replaceable>kernel parameter</replaceable>}</varname></term> |
188 | <listitem> | |
189 | <para>Match a kernel parameter value. | |
190 | </para> | |
191 | </listitem> | |
63749b1a KS |
192 | </varlistentry> |
193 | ||
194 | <varlistentry> | |
909f413d | 195 | <term><varname>KERNELS</varname></term> |
63749b1a KS |
196 | <listitem> |
197 | <para>Search the devpath upwards for a matching device name.</para> | |
198 | </listitem> | |
199 | </varlistentry> | |
200 | ||
201 | <varlistentry> | |
909f413d | 202 | <term><varname>SUBSYSTEMS</varname></term> |
63749b1a KS |
203 | <listitem> |
204 | <para>Search the devpath upwards for a matching device subsystem name.</para> | |
205 | </listitem> | |
206 | </varlistentry> | |
207 | ||
208 | <varlistentry> | |
909f413d | 209 | <term><varname>DRIVERS</varname></term> |
63749b1a KS |
210 | <listitem> |
211 | <para>Search the devpath upwards for a matching device driver name.</para> | |
212 | </listitem> | |
213 | </varlistentry> | |
214 | ||
215 | <varlistentry> | |
909f413d | 216 | <term><varname>ATTRS{<replaceable>filename</replaceable>}</varname></term> |
63749b1a KS |
217 | <listitem> |
218 | <para>Search the devpath upwards for a device with matching sysfs attribute values. | |
909f413d | 219 | If multiple <varname>ATTRS</varname> matches are specified, all of them |
65e039c2 MW |
220 | must match on the same device. Trailing whitespace in the attribute values is ignored |
221 | unless the specified match value itself contains trailing whitespace.</para> | |
63749b1a KS |
222 | </listitem> |
223 | </varlistentry> | |
224 | ||
7df0ed83 | 225 | <varlistentry> |
909f413d | 226 | <term><varname>TAGS</varname></term> |
7df0ed83 KS |
227 | <listitem> |
228 | <para>Search the devpath upwards for a device with matching tag.</para> | |
229 | </listitem> | |
230 | </varlistentry> | |
231 | ||
63749b1a | 232 | <varlistentry> |
909f413d | 233 | <term><varname>ENV{<replaceable>key</replaceable>}</varname></term> |
63749b1a KS |
234 | <listitem> |
235 | <para>Match against a device property value.</para> | |
236 | </listitem> | |
237 | </varlistentry> | |
238 | ||
4801d8af JS |
239 | <varlistentry> |
240 | <term><varname>CONST{<replaceable>key</replaceable>}</varname></term> | |
241 | <listitem> | |
242 | <para>Match against a system-wide constant. Supported keys are:</para> | |
243 | <variablelist> | |
244 | <varlistentry> | |
245 | <term><literal>arch</literal></term> | |
246 | <listitem> | |
247 | <para>System's architecture. See <option>ConditionArchitecture=</option> in | |
248 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
249 | for possible values.</para> | |
250 | </listitem> | |
251 | </varlistentry> | |
252 | <varlistentry> | |
253 | <term><literal>virt</literal></term> | |
254 | <listitem> | |
255 | <para>System's virtualization environment. See | |
256 | <citerefentry><refentrytitle>systemd-detect-virt</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
257 | for possible values.</para> | |
258 | </listitem> | |
259 | </varlistentry> | |
260 | </variablelist> | |
261 | <para>Unknown keys will never match.</para> | |
262 | </listitem> | |
263 | </varlistentry> | |
264 | ||
63749b1a | 265 | <varlistentry> |
909f413d | 266 | <term><varname>TAG</varname></term> |
63749b1a KS |
267 | <listitem> |
268 | <para>Match against a device tag.</para> | |
269 | </listitem> | |
270 | </varlistentry> | |
271 | ||
272 | <varlistentry> | |
909f413d | 273 | <term><varname>TEST{<replaceable>octal mode mask</replaceable>}</varname></term> |
63749b1a KS |
274 | <listitem> |
275 | <para>Test the existence of a file. An octal mode mask can be specified | |
276 | if needed.</para> | |
277 | </listitem> | |
278 | </varlistentry> | |
279 | ||
280 | <varlistentry> | |
909f413d | 281 | <term><varname>PROGRAM</varname></term> |
63749b1a | 282 | <listitem> |
12254cca ZJS |
283 | <para>Execute a program to determine whether there is a match; the key is true if the program |
284 | returns successfully. The device properties are made available to the executed program in the | |
285 | environment. The program's standard output is available in the <varname>RESULT</varname> | |
286 | key.</para> | |
287 | ||
288 | <para>This can only be used for very short-running foreground tasks. For details, see | |
289 | <varname>RUN</varname>.</para> | |
290 | ||
291 | <para>Note that multiple <varname>PROGRAM</varname> keys may be specified in one rule, and | |
292 | <literal>=</literal>, <literal>:=</literal>, and <literal>+=</literal> have the same effect as | |
293 | <literal>==</literal>.</para> | |
63749b1a KS |
294 | </listitem> |
295 | </varlistentry> | |
296 | ||
297 | <varlistentry> | |
909f413d | 298 | <term><varname>RESULT</varname></term> |
63749b1a | 299 | <listitem> |
bcddd5bf JSJ |
300 | <para>Match the returned string of the last <varname>PROGRAM</varname> call. |
301 | This key can be used in the same or in any later rule after a | |
302 | <varname>PROGRAM</varname> call.</para> | |
63749b1a KS |
303 | </listitem> |
304 | </varlistentry> | |
305 | </variablelist> | |
306 | ||
bf2e0ece AB |
307 | <para>Most of the fields support shell glob pattern matching and |
308 | alternate patterns. The following special characters are supported:</para> | |
63749b1a KS |
309 | <variablelist> |
310 | <varlistentry> | |
6b76fa66 | 311 | <term><literal>*</literal></term> |
63749b1a | 312 | <listitem> |
954e9c52 | 313 | <para>Matches zero or more characters.</para> |
63749b1a KS |
314 | </listitem> |
315 | </varlistentry> | |
316 | <varlistentry> | |
6b76fa66 | 317 | <term><literal>?</literal></term> |
63749b1a KS |
318 | <listitem> |
319 | <para>Matches any single character.</para> | |
320 | </listitem> | |
321 | </varlistentry> | |
322 | <varlistentry> | |
6b76fa66 | 323 | <term><literal>[]</literal></term> |
63749b1a KS |
324 | <listitem> |
325 | <para>Matches any single character specified within the brackets. For | |
909f413d ZJS |
326 | example, the pattern string <literal>tty[SR]</literal> |
327 | would match either <literal>ttyS</literal> or <literal>ttyR</literal>. | |
328 | Ranges are also supported via the <literal>-</literal> character. | |
bcddd5bf JSJ |
329 | For example, to match on the range of all digits, the pattern |
330 | <literal>[0-9]</literal> could be used. If the first character | |
331 | following the <literal>[</literal> is a <literal>!</literal>, | |
332 | any characters not enclosed are matched.</para> | |
63749b1a KS |
333 | </listitem> |
334 | </varlistentry> | |
bf2e0ece AB |
335 | <varlistentry> |
336 | <term><literal>|</literal></term> | |
337 | <listitem> | |
338 | <para>Separates alternative patterns. For example, the pattern string | |
339 | <literal>abc|x*</literal> would match either <literal>abc</literal> | |
340 | or <literal>x*</literal>.</para> | |
341 | </listitem> | |
342 | </varlistentry> | |
63749b1a KS |
343 | </variablelist> |
344 | ||
345 | <para>The following keys can get values assigned:</para> | |
ccc9a4f9 | 346 | <variablelist class='udev-directives'> |
63749b1a | 347 | <varlistentry> |
909f413d | 348 | <term><varname>NAME</varname></term> |
63749b1a | 349 | <listitem> |
1ff28eae TG |
350 | <para>The name to use for a network interface. See |
351 | <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
352 | for a higher-level mechanism for setting the interface name. | |
353 | The name of a device node cannot be changed by udev, only additional | |
354 | symlinks can be created.</para> | |
63749b1a KS |
355 | </listitem> |
356 | </varlistentry> | |
357 | ||
358 | <varlistentry> | |
909f413d | 359 | <term><varname>SYMLINK</varname></term> |
63749b1a | 360 | <listitem> |
933b5623 | 361 | <para>The name of a symlink targeting the node. Every matching rule adds |
b1239c3f KS |
362 | this value to the list of symlinks to be created.</para> |
363 | <para>The set of characters to name a symlink is limited. Allowed | |
909f413d ZJS |
364 | characters are <literal>0-9A-Za-z#+-.:=@_/</literal>, valid UTF-8 character |
365 | sequences, and <literal>\x00</literal> hex encoding. All other | |
366 | characters are replaced by a <literal>_</literal> character.</para> | |
b1239c3f KS |
367 | <para>Multiple symlinks may be specified by separating the names by the |
368 | space character. In case multiple devices claim the same name, the link | |
369 | always points to the device with the highest link_priority. If the current | |
370 | device goes away, the links are re-evaluated and the device with the | |
371 | next highest link_priority becomes the owner of the link. If no | |
372 | link_priority is specified, the order of the devices (and which one of | |
373 | them owns the link) is undefined.</para> | |
374 | <para>Symlink names must never conflict with the kernel's default device | |
375 | node names, as that would result in unpredictable behavior. | |
63749b1a KS |
376 | </para> |
377 | </listitem> | |
378 | </varlistentry> | |
379 | ||
380 | <varlistentry> | |
909f413d | 381 | <term><varname>OWNER</varname>, <varname>GROUP</varname>, <varname>MODE</varname></term> |
63749b1a | 382 | <listitem> |
91418155 | 383 | <para>The permissions for the device node. Every specified value overrides |
63749b1a KS |
384 | the compiled-in default value.</para> |
385 | </listitem> | |
386 | </varlistentry> | |
387 | ||
c26547d6 KS |
388 | <varlistentry> |
389 | <term><varname>SECLABEL{<replaceable>module</replaceable>}</varname></term> | |
390 | <listitem> | |
391 | <para>Applies the specified Linux Security Module label to the device node.</para> | |
392 | </listitem> | |
393 | </varlistentry> | |
394 | ||
63749b1a | 395 | <varlistentry> |
909f413d | 396 | <term><varname>ATTR{<replaceable>key</replaceable>}</varname></term> |
63749b1a KS |
397 | <listitem> |
398 | <para>The value that should be written to a sysfs attribute of the | |
399 | event device.</para> | |
400 | </listitem> | |
401 | </varlistentry> | |
402 | ||
f4cf2e5b KS |
403 | <varlistentry> |
404 | <term><varname>SYSCTL{<replaceable>kernel parameter</replaceable>}</varname></term> | |
405 | <listitem> | |
406 | <para>The value that should be written to kernel parameter.</para> | |
407 | </listitem> | |
408 | </varlistentry> | |
409 | ||
63749b1a | 410 | <varlistentry> |
909f413d | 411 | <term><varname>ENV{<replaceable>key</replaceable>}</varname></term> |
63749b1a | 412 | <listitem> |
909f413d | 413 | <para>Set a device property value. Property names with a leading <literal>.</literal> |
ed9c5fb7 | 414 | are neither stored in the database nor exported to events or |
bcddd5bf JSJ |
415 | external tools (run by, for example, the <varname>PROGRAM</varname> |
416 | match key).</para> | |
63749b1a KS |
417 | </listitem> |
418 | </varlistentry> | |
419 | ||
420 | <varlistentry> | |
909f413d | 421 | <term><varname>TAG</varname></term> |
63749b1a KS |
422 | <listitem> |
423 | <para>Attach a tag to a device. This is used to filter events for users | |
424 | of libudev's monitor functionality, or to enumerate a group of tagged | |
425 | devices. The implementation can only work efficiently if only a few | |
426 | tags are attached to a device. It is only meant to be used in | |
427 | contexts with specific device filter requirements, and not as a | |
428 | general-purpose flag. Excessive use might result in inefficient event | |
429 | handling.</para> | |
430 | </listitem> | |
431 | </varlistentry> | |
432 | ||
433 | <varlistentry> | |
909f413d | 434 | <term><varname>RUN{<replaceable>type</replaceable>}</varname></term> |
63749b1a | 435 | <listitem> |
12254cca ZJS |
436 | <para>Specify a program to be executed after processing of all the rules for the event. With |
437 | <literal>+=</literal>, this invocation is added to the list, and with <literal>=</literal> or | |
438 | <literal>:=</literal>, it replaces any previous contents of the list. Please note that both | |
439 | <literal>program</literal> and <literal>builtin</literal> types described below use a single | |
440 | list, so clearing the list with <literal>:=</literal> and <literal>=</literal> affects both | |
441 | types.</para> | |
442 | ||
443 | <para><replaceable>type</replaceable> may be:</para> | |
72c6cf8f TG |
444 | <variablelist> |
445 | <varlistentry> | |
446 | <term><literal>program</literal></term> | |
447 | <listitem> | |
448 | <para>Execute an external program specified as the assigned | |
bcddd5bf | 449 | value. If no absolute path is given, the program is expected |
12b42c76 | 450 | to live in <filename>/usr/lib/udev</filename>; otherwise, the |
bcddd5bf JSJ |
451 | absolute path must be specified.</para> |
452 | <para>This is the default if no <replaceable>type</replaceable> | |
453 | is specified.</para> | |
72c6cf8f TG |
454 | </listitem> |
455 | </varlistentry> | |
456 | <varlistentry> | |
457 | <term><literal>builtin</literal></term> | |
458 | <listitem> | |
bcddd5bf JSJ |
459 | <para>As <varname>program</varname>, but use one of the |
460 | built-in programs rather than an external one.</para> | |
72c6cf8f TG |
461 | </listitem> |
462 | </varlistentry> | |
463 | </variablelist> | |
12254cca ZJS |
464 | |
465 | <para>The program name and following arguments are separated by spaces. Single quotes can be | |
466 | used to specify arguments with spaces.</para> | |
467 | ||
468 | <para>This can only be used for very short-running foreground tasks. Running an event process for | |
469 | a long period of time may block all further events for this or a dependent device.</para> | |
470 | ||
471 | <para>Note that running programs that access the network or mount/unmount filesystems is not | |
472 | allowed inside of udev rules, due to the default sandbox that is enforced on | |
473 | <filename>systemd-udevd.service</filename>.</para> | |
474 | ||
475 | <para>Starting daemons or other long-running processes is not allowed; the forked processes, | |
476 | detached or not, will be unconditionally killed after the event handling has finished. In order | |
477 | to activate long-running processes from udev rules, provide a service unit and pull it in from a | |
478 | udev device using the <varname>SYSTEMD_WANTS</varname> device property. See | |
49dd0c16 LP |
479 | <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry> |
480 | for details.</para> | |
63749b1a KS |
481 | </listitem> |
482 | </varlistentry> | |
483 | ||
484 | <varlistentry> | |
909f413d | 485 | <term><varname>LABEL</varname></term> |
63749b1a | 486 | <listitem> |
bcddd5bf | 487 | <para>A named label to which a <varname>GOTO</varname> may jump.</para> |
63749b1a KS |
488 | </listitem> |
489 | </varlistentry> | |
490 | ||
491 | <varlistentry> | |
909f413d | 492 | <term><varname>GOTO</varname></term> |
63749b1a | 493 | <listitem> |
bcddd5bf | 494 | <para>Jumps to the next <varname>LABEL</varname> with a matching name.</para> |
63749b1a KS |
495 | </listitem> |
496 | </varlistentry> | |
497 | ||
498 | <varlistentry> | |
909f413d | 499 | <term><varname>IMPORT{<replaceable>type</replaceable>}</varname></term> |
63749b1a | 500 | <listitem> |
12254cca ZJS |
501 | <para>Import a set of variables as device properties, depending on |
502 | <replaceable>type</replaceable>:</para> | |
503 | ||
63749b1a KS |
504 | <variablelist> |
505 | <varlistentry> | |
6b76fa66 | 506 | <term><literal>program</literal></term> |
63749b1a | 507 | <listitem> |
9de4d0ce | 508 | <para>Execute an external program specified as the assigned |
b938cb90 | 509 | value and, if it returns successfully, |
63749b1a KS |
510 | import its output, which must be in environment key |
511 | format. Path specification, command/argument separation, | |
909f413d | 512 | and quoting work like in <varname>RUN</varname>.</para> |
63749b1a KS |
513 | </listitem> |
514 | </varlistentry> | |
515 | <varlistentry> | |
72c6cf8f TG |
516 | <term><literal>builtin</literal></term> |
517 | <listitem> | |
909f413d ZJS |
518 | <para>Similar to <literal>program</literal>, but use one of the |
519 | built-in programs rather than an external one.</para> | |
72c6cf8f TG |
520 | </listitem> |
521 | </varlistentry> | |
522 | <varlistentry> | |
6b76fa66 | 523 | <term><literal>file</literal></term> |
63749b1a | 524 | <listitem> |
b6a49cd6 MW |
525 | <para>Import a text file specified as the assigned value, the content |
526 | of which must be in environment key format.</para> | |
63749b1a KS |
527 | </listitem> |
528 | </varlistentry> | |
529 | <varlistentry> | |
6b76fa66 | 530 | <term><literal>db</literal></term> |
63749b1a KS |
531 | <listitem> |
532 | <para>Import a single property specified as the assigned value from the | |
533 | current device database. This works only if the database is already populated | |
534 | by an earlier event.</para> | |
535 | </listitem> | |
536 | </varlistentry> | |
c4f6dcc4 | 537 | <varlistentry> |
6b76fa66 | 538 | <term><literal>cmdline</literal></term> |
c4f6dcc4 | 539 | <listitem> |
ad9c70a8 | 540 | <para>Import a single property from the kernel command line. For simple flags |
909f413d | 541 | the value of the property is set to <literal>1</literal>.</para> |
c4f6dcc4 KS |
542 | </listitem> |
543 | </varlistentry> | |
63749b1a | 544 | <varlistentry> |
6b76fa66 | 545 | <term><literal>parent</literal></term> |
63749b1a KS |
546 | <listitem> |
547 | <para>Import the stored keys from the parent device by reading | |
548 | the database entry of the parent device. The value assigned to | |
549 | <option>IMPORT{parent}</option> is used as a filter of key names | |
eb75d0ed | 550 | to import (with the same shell glob pattern matching used for |
63749b1a KS |
551 | comparisons).</para> |
552 | </listitem> | |
553 | </varlistentry> | |
554 | </variablelist> | |
12254cca ZJS |
555 | |
556 | <para>This can only be used for very short-running foreground tasks. For details see | |
557 | <option>RUN</option>.</para> | |
558 | ||
559 | <para>Note that multiple <varname>IMPORT{}</varname> keys may be specified in one rule, and | |
560 | <literal>=</literal>, <literal>:=</literal>, and <literal>+=</literal> have the same effect as | |
561 | <literal>==</literal>. The key is true if the import is successful, unless <literal>!=</literal> | |
562 | is used as the operator which causes the key to be true if the import failed.</para> | |
63749b1a KS |
563 | </listitem> |
564 | </varlistentry> | |
565 | ||
63749b1a | 566 | <varlistentry> |
909f413d | 567 | <term><varname>OPTIONS</varname></term> |
63749b1a KS |
568 | <listitem> |
569 | <para>Rule and device options:</para> | |
ccc9a4f9 | 570 | <variablelist class='udev-directives'> |
63749b1a KS |
571 | <varlistentry> |
572 | <term><option>link_priority=<replaceable>value</replaceable></option></term> | |
573 | <listitem> | |
574 | <para>Specify the priority of the created symlinks. Devices with higher | |
575 | priorities overwrite existing symlinks of other devices. The default is 0.</para> | |
576 | </listitem> | |
577 | </varlistentry> | |
63749b1a KS |
578 | <varlistentry> |
579 | <term><option>string_escape=<replaceable>none|replace</replaceable></option></term> | |
580 | <listitem> | |
b938cb90 | 581 | <para>Usually, control and other possibly unsafe characters are replaced |
63749b1a KS |
582 | in strings used for device naming. The mode of replacement can be specified |
583 | with this option.</para> | |
584 | </listitem> | |
585 | </varlistentry> | |
9fa68615 KS |
586 | <varlistentry> |
587 | <term><option>static_node=</option></term> | |
588 | <listitem> | |
bcddd5bf JSJ |
589 | <para>Apply the permissions specified in this rule to the |
590 | static device node with the specified name. Also, for every | |
591 | tag specified in this rule, create a symlink | |
84b6ad70 TG |
592 | in the directory |
593 | <filename>/run/udev/static_node-tags/<replaceable>tag</replaceable></filename> | |
bcddd5bf JSJ |
594 | pointing at the static device node with the specified name. |
595 | Static device node creation is performed by systemd-tmpfiles | |
596 | before systemd-udevd is started. The static nodes might not | |
597 | have a corresponding kernel device; they are used to trigger | |
598 | automatic kernel module loading when they are accessed.</para> | |
9fa68615 KS |
599 | </listitem> |
600 | </varlistentry> | |
63749b1a KS |
601 | <varlistentry> |
602 | <term><option>watch</option></term> | |
603 | <listitem> | |
bcddd5bf JSJ |
604 | <para>Watch the device node with inotify; when the node is |
605 | closed after being opened for writing, a change uevent is | |
606 | synthesized.</para> | |
63749b1a KS |
607 | </listitem> |
608 | </varlistentry> | |
3b529da4 KS |
609 | <varlistentry> |
610 | <term><option>nowatch</option></term> | |
611 | <listitem> | |
612 | <para>Disable the watching of a device node with inotify.</para> | |
613 | </listitem> | |
614 | </varlistentry> | |
07d16cc0 MS |
615 | <varlistentry> |
616 | <term><option>db_persist</option></term> | |
617 | <listitem> | |
618 | <para>Set the flag (sticky bit) on the udev database entry | |
619 | of the event device. Device properties are then kept in the | |
620 | database even when | |
621 | <command>udevadm info --cleanup-db</command> is called. | |
622 | This option can be useful in certain cases | |
623 | (e.g. Device Mapper devices) for persisting device state | |
624 | on the transition from initramfs.</para> | |
625 | </listitem> | |
626 | </varlistentry> | |
63749b1a KS |
627 | </variablelist> |
628 | </listitem> | |
629 | </varlistentry> | |
630 | </variablelist> | |
631 | ||
bcddd5bf JSJ |
632 | <para>The <varname>NAME</varname>, <varname>SYMLINK</varname>, |
633 | <varname>PROGRAM</varname>, <varname>OWNER</varname>, | |
4f985bd8 MS |
634 | <varname>GROUP</varname>, <varname>MODE</varname>, <varname>SECLABEL</varname>, |
635 | and <varname>RUN</varname> fields support simple string substitutions. | |
bcddd5bf JSJ |
636 | The <varname>RUN</varname> substitutions are performed after all rules |
637 | have been processed, right before the program is executed, allowing for | |
638 | the use of device properties set by earlier matching rules. For all other | |
639 | fields, substitutions are performed while the individual rule is being | |
640 | processed. The available substitutions are:</para> | |
ccc9a4f9 | 641 | <variablelist class='udev-directives'> |
63749b1a KS |
642 | <varlistentry> |
643 | <term><option>$kernel</option>, <option>%k</option></term> | |
644 | <listitem> | |
645 | <para>The kernel name for this device.</para> | |
646 | </listitem> | |
647 | </varlistentry> | |
648 | ||
649 | <varlistentry> | |
650 | <term><option>$number</option>, <option>%n</option></term> | |
651 | <listitem> | |
12254cca ZJS |
652 | <para>The kernel number for this device. For example, <literal>sda3</literal> has kernel number |
653 | 3.</para> | |
63749b1a KS |
654 | </listitem> |
655 | </varlistentry> | |
656 | ||
657 | <varlistentry> | |
658 | <term><option>$devpath</option>, <option>%p</option></term> | |
659 | <listitem> | |
660 | <para>The devpath of the device.</para> | |
661 | </listitem> | |
662 | </varlistentry> | |
663 | ||
664 | <varlistentry> | |
665 | <term><option>$id</option>, <option>%b</option></term> | |
666 | <listitem> | |
bcddd5bf JSJ |
667 | <para>The name of the device matched while searching the devpath |
668 | upwards for <option>SUBSYSTEMS</option>, <option>KERNELS</option>, | |
669 | <option>DRIVERS</option>, and <option>ATTRS</option>. | |
63749b1a KS |
670 | </para> |
671 | </listitem> | |
672 | </varlistentry> | |
673 | ||
674 | <varlistentry> | |
675 | <term><option>$driver</option></term> | |
676 | <listitem> | |
bcddd5bf JSJ |
677 | <para>The driver name of the device matched while searching the |
678 | devpath upwards for <option>SUBSYSTEMS</option>, | |
679 | <option>KERNELS</option>, <option>DRIVERS</option>, and | |
680 | <option>ATTRS</option>. | |
63749b1a KS |
681 | </para> |
682 | </listitem> | |
683 | </varlistentry> | |
684 | ||
685 | <varlistentry> | |
686 | <term><option>$attr{<replaceable>file</replaceable>}</option>, <option>%s{<replaceable>file</replaceable>}</option></term> | |
687 | <listitem> | |
0e846301 | 688 | <para>The value of a sysfs attribute found at the device where |
bcddd5bf JSJ |
689 | all keys of the rule have matched. If the matching device does not |
690 | have such an attribute, and a previous <option>KERNELS</option>, | |
691 | <option>SUBSYSTEMS</option>, <option>DRIVERS</option>, or | |
692 | <option>ATTRS</option> test selected a parent device, then the | |
693 | attribute from that parent device is used. | |
694 | </para> | |
695 | <para>If the attribute is a symlink, the last element of the | |
696 | symlink target is returned as the value. | |
697 | </para> | |
63749b1a KS |
698 | </listitem> |
699 | </varlistentry> | |
700 | ||
701 | <varlistentry> | |
702 | <term><option>$env{<replaceable>key</replaceable>}</option>, <option>%E{<replaceable>key</replaceable>}</option></term> | |
703 | <listitem> | |
704 | <para>A device property value.</para> | |
705 | </listitem> | |
706 | </varlistentry> | |
707 | ||
708 | <varlistentry> | |
709 | <term><option>$major</option>, <option>%M</option></term> | |
710 | <listitem> | |
711 | <para>The kernel major number for the device.</para> | |
712 | </listitem> | |
713 | </varlistentry> | |
714 | ||
715 | <varlistentry> | |
716 | <term><option>$minor</option>, <option>%m</option></term> | |
717 | <listitem> | |
718 | <para>The kernel minor number for the device.</para> | |
719 | </listitem> | |
720 | </varlistentry> | |
721 | ||
722 | <varlistentry> | |
723 | <term><option>$result</option>, <option>%c</option></term> | |
724 | <listitem> | |
bcddd5bf JSJ |
725 | <para>The string returned by the external program requested with |
726 | <varname>PROGRAM</varname>. | |
21188522 | 727 | A single part of the string, separated by a space character, may be selected |
909f413d ZJS |
728 | by specifying the part number as an attribute: <literal>%c{N}</literal>. |
729 | If the number is followed by the <literal>+</literal> character, this part plus all remaining parts | |
730 | of the result string are substituted: <literal>%c{N+}</literal>.</para> | |
63749b1a KS |
731 | </listitem> |
732 | </varlistentry> | |
733 | ||
734 | <varlistentry> | |
735 | <term><option>$parent</option>, <option>%P</option></term> | |
736 | <listitem> | |
737 | <para>The node name of the parent device.</para> | |
738 | </listitem> | |
739 | </varlistentry> | |
740 | ||
741 | <varlistentry> | |
742 | <term><option>$name</option></term> | |
743 | <listitem> | |
220893b3 | 744 | <para>The current name of the device. If not changed by a rule, it is the |
63749b1a KS |
745 | name of the kernel device.</para> |
746 | </listitem> | |
747 | </varlistentry> | |
748 | ||
749 | <varlistentry> | |
750 | <term><option>$links</option></term> | |
751 | <listitem> | |
e8b5e4e5 | 752 | <para>A space-separated list of the current symlinks. The value is |
2d74bc75 | 753 | only set during a remove event or if an earlier rule assigned a value.</para> |
63749b1a KS |
754 | </listitem> |
755 | </varlistentry> | |
756 | ||
757 | <varlistentry> | |
758 | <term><option>$root</option>, <option>%r</option></term> | |
759 | <listitem> | |
760 | <para>The udev_root value.</para> | |
761 | </listitem> | |
762 | </varlistentry> | |
763 | ||
764 | <varlistentry> | |
765 | <term><option>$sys</option>, <option>%S</option></term> | |
766 | <listitem> | |
767 | <para>The sysfs mount point.</para> | |
768 | </listitem> | |
769 | </varlistentry> | |
770 | ||
771 | <varlistentry> | |
220893b3 | 772 | <term><option>$devnode</option>, <option>%N</option></term> |
63749b1a | 773 | <listitem> |
220893b3 | 774 | <para>The name of the device node.</para> |
63749b1a KS |
775 | </listitem> |
776 | </varlistentry> | |
777 | ||
778 | <varlistentry> | |
909f413d | 779 | <term><option>%%</option></term> |
63749b1a | 780 | <listitem> |
909f413d | 781 | <para>The <literal>%</literal> character itself.</para> |
63749b1a KS |
782 | </listitem> |
783 | </varlistentry> | |
784 | ||
785 | <varlistentry> | |
909f413d | 786 | <term><option>$$</option></term> |
63749b1a | 787 | <listitem> |
909f413d | 788 | <para>The <literal>$</literal> character itself.</para> |
63749b1a KS |
789 | </listitem> |
790 | </varlistentry> | |
791 | </variablelist> | |
63749b1a KS |
792 | </refsect1> |
793 | ||
63749b1a KS |
794 | <refsect1> |
795 | <title>See Also</title> | |
bcddd5bf JSJ |
796 | <para> |
797 | <citerefentry> | |
b79f817b | 798 | <refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum> |
ad29a9f1 | 799 | </citerefentry>, |
63749b1a KS |
800 | <citerefentry> |
801 | <refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum> | |
2b09983f | 802 | </citerefentry>, |
1ff28eae TG |
803 | <citerefentry> |
804 | <refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum> | |
805 | </citerefentry> | |
bcddd5bf | 806 | </para> |
63749b1a KS |
807 | </refsect1> |
808 | </refentry> |