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1 | <?xml version='1.0'?> |
2 | <!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | |
3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
4 | ||
5 | <article> | |
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6 | <section> |
7 | <title>udev</title> | |
8 | <refentry> | |
9 | <refentryinfo> | |
10 | <title>udev</title> | |
11 | <date>August 2005</date> | |
12 | <productname>udev</productname> | |
13 | </refentryinfo> | |
14 | ||
15 | <refmeta> | |
16 | <refentrytitle>udev</refentrytitle> | |
2c769419 | 17 | <manvolnum>7</manvolnum> |
660508cd | 18 | <refmiscinfo class="version"></refmiscinfo> |
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19 | </refmeta> |
20 | ||
21 | <refnamediv> | |
22 | <refname>udev</refname> | |
23 | <refpurpose>dynamic device management</refpurpose> | |
24 | </refnamediv> | |
25 | ||
26 | <refsect1><title>DESCRIPTION</title> | |
27 | <para>udev provides a dynamic device directory containing only the files for | |
28 | actually present devices. It creates or removes device node files in the | |
29 | <filename>/dev</filename> directory, or it renames network interfaces.</para> | |
30 | ||
31 | <para>Usually udev runs as <citerefentry><refentrytitle>udevd</refentrytitle> | |
32 | <manvolnum>8</manvolnum></citerefentry> and receives uevents directly from the | |
7f723806 | 33 | kernel if a device is added or removed from the system.</para> |
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34 | |
35 | <para>If udev receives a device event, it matches its configured rules | |
36 | against the available device attributes provided in sysfs to identify the device. | |
7f723806 | 37 | Rules that match may provide additional device information or specify a device |
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38 | node name and multiple symlink names and instruct udev to run additional programs |
39 | as part of the device event handling.</para> | |
40 | </refsect1> | |
41 | ||
42 | <refsect1><title>CONFIGURATION</title> | |
43 | <para>All udev configuration files are placed in <filename>/etc/udev/*</filename>. | |
309d6fd3 | 44 | Every file consists of a set of lines of text. All empty lines or lines beginning |
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45 | with '#' will be ignored.</para> |
46 | ||
47 | <refsect2><title>Configuration file</title> | |
48 | <para>udev expects its main configuration file at <filename>/etc/udev/udev.conf</filename>. | |
49 | It consists of a set of variables allowing the user to override default udev values. | |
50 | The following variables can be set:</para> | |
51 | <variablelist> | |
52 | <varlistentry> | |
53 | <term><option>udev_root</option></term> | |
54 | <listitem> | |
55 | <para>Specifies where to place the device nodes in the filesystem. | |
56 | The default value is <filename>/dev</filename>.</para> | |
57 | </listitem> | |
58 | </varlistentry> | |
59 | ||
7b86ada7 KS |
60 | <varlistentry> |
61 | <term><option>udev_rules</option></term> | |
62 | <listitem> | |
63 | <para>The name of the udev rules file or directory to look for files | |
64 | with the suffix <filename>.rules</filename>. Multiple rule files are | |
65 | read in lexical order. The default value is | |
66 | <filename>/etc/udev/rules.d</filename>.</para> | |
67 | </listitem> | |
68 | </varlistentry> | |
69 | ||
70 | <varlistentry> | |
71 | <term><option>udev_log</option></term> | |
72 | <listitem> | |
73 | <para>The logging priority. Valid values are the numerical syslog priorities | |
74 | or their textual representations: <option>err</option>, <option>info</option> | |
75 | and <option>debug</option>.</para> | |
76 | </listitem> | |
77 | </varlistentry> | |
78 | </variablelist> | |
79 | </refsect2> | |
80 | ||
81 | <refsect2><title>Rules files</title> | |
82 | <para>The udev rules are read from the files located in the | |
83 | <filename>/etc/udev/rules.d</filename> directory or at the location specified | |
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84 | value in the configuration file. Every line in the rules file contains at least |
85 | one key value pair. There are two kind of keys, match and assignment keys. | |
7b86ada7 | 86 | If all match keys are matching against its value, the rule gets applied and the |
e7c39acb KS |
87 | assign keys get the specified value assigned.</para> |
88 | ||
89 | <para>A matching rule may specify the name of the device node, add a symlink | |
90 | pointing to the node, or run a specified program as part of the event handling. | |
91 | If no matching rule is found, the default device node name is used.</para> | |
7b86ada7 | 92 | |
7f723806 | 93 | <para>A rule may consist of a list of one or more key value pairs separated by |
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94 | a comma. Each key has a distinct operation, depending on the used operator. Valid |
95 | operators are:</para> | |
96 | <variablelist> | |
97 | <varlistentry> | |
98 | <term><option>==</option></term> | |
99 | <listitem> | |
100 | <para>Compare for equality.</para> | |
101 | </listitem> | |
102 | </varlistentry> | |
103 | ||
104 | <varlistentry> | |
105 | <term><option>!=</option></term> | |
106 | <listitem> | |
107 | <para>Compare for non-equality.</para> | |
108 | </listitem> | |
109 | </varlistentry> | |
110 | ||
111 | <varlistentry> | |
112 | <term><option>=</option></term> | |
113 | <listitem> | |
226b9692 | 114 | <para>Assign a value to a key. Keys that represent a list, are reset |
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115 | and only this single value is assigned.</para> |
116 | </listitem> | |
117 | </varlistentry> | |
118 | ||
119 | <varlistentry> | |
120 | <term><option>+=</option></term> | |
121 | <listitem> | |
122 | <para>Add the value to a key that holds a list of entries.</para> | |
123 | </listitem> | |
124 | </varlistentry> | |
125 | ||
126 | <varlistentry> | |
127 | <term><option>:=</option></term> | |
128 | <listitem> | |
129 | <para>Assign a value to a key finally; disallow any later changes, | |
130 | which may be used to prevent changes by any later rules.</para> | |
131 | </listitem> | |
132 | </varlistentry> | |
133 | </variablelist> | |
134 | ||
e7c39acb KS |
135 | <para>The following key names can be used to match against device properties. |
136 | Some of the keys also match against properties of the parent devices in sysfs, | |
137 | not only the device that has generated the event. If multiple keys that match | |
138 | a parent device are specified in a single rule, all these keys must match at | |
139 | one and the same parent device.</para> | |
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140 | <variablelist> |
141 | <varlistentry> | |
142 | <term><option>ACTION</option></term> | |
143 | <listitem> | |
03b24b71 | 144 | <para>Match the name of the event action.</para> |
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145 | </listitem> |
146 | </varlistentry> | |
147 | ||
148 | <varlistentry> | |
95776dc6 | 149 | <term><option>DEVPATH</option></term> |
7b86ada7 | 150 | <listitem> |
95776dc6 | 151 | <para>Match the devpath of the event device.</para> |
7b86ada7 KS |
152 | </listitem> |
153 | </varlistentry> | |
154 | ||
155 | <varlistentry> | |
95776dc6 | 156 | <term><option>KERNEL</option></term> |
7b86ada7 | 157 | <listitem> |
95776dc6 | 158 | <para>Match the name of the event device.</para> |
7b86ada7 KS |
159 | </listitem> |
160 | </varlistentry> | |
161 | ||
162 | <varlistentry> | |
163 | <term><option>SUBSYSTEM</option></term> | |
164 | <listitem> | |
95776dc6 KS |
165 | <para>Match the subsystem of the event device.</para> |
166 | </listitem> | |
167 | </varlistentry> | |
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168 | <varlistentry> |
169 | <term><option>DRIVER</option></term> | |
170 | <listitem> | |
e7c39acb KS |
171 | <para>Match the driver name of the event device. Only set for devices |
172 | which are bound to a driver at the time the event is generated.</para> | |
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173 | </listitem> |
174 | </varlistentry> | |
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175 | <varlistentry> |
176 | <term><option>ATTR{<replaceable>filename</replaceable>}</option></term> | |
177 | <listitem> | |
178 | <para>Match sysfs attribute values of the event device. Up to five | |
179 | <option>ATTR</option> keys can be specified per rule. Trailing | |
180 | whitespace in the attribute values is ignored, if the specified match | |
02adc0cb KS |
181 | value does not contain trailing whitespace itself. Depending on the type |
182 | of operator, this key is also used to set the value of a sysfs attribute. | |
183 | </para> | |
7b86ada7 KS |
184 | </listitem> |
185 | </varlistentry> | |
186 | ||
187 | <varlistentry> | |
95776dc6 | 188 | <term><option>KERNELS</option></term> |
7b86ada7 | 189 | <listitem> |
95776dc6 | 190 | <para>Search the devpath upwards for a matching device name.</para> |
7b86ada7 KS |
191 | </listitem> |
192 | </varlistentry> | |
193 | ||
194 | <varlistentry> | |
95776dc6 | 195 | <term><option>SUBSYSTEMS</option></term> |
7b86ada7 | 196 | <listitem> |
95776dc6 | 197 | <para>Search the devpath upwards for a matching device subsystem name.</para> |
7b86ada7 KS |
198 | </listitem> |
199 | </varlistentry> | |
200 | ||
201 | <varlistentry> | |
95776dc6 | 202 | <term><option>DRIVERS</option></term> |
7b86ada7 | 203 | <listitem> |
95776dc6 | 204 | <para>Search the devpath upwards for a matching device driver name.</para> |
7b86ada7 KS |
205 | </listitem> |
206 | </varlistentry> | |
207 | ||
208 | <varlistentry> | |
95776dc6 | 209 | <term><option>ATTRS{<replaceable>filename</replaceable>}</option></term> |
7b86ada7 | 210 | <listitem> |
03b24b71 | 211 | <para>Search the devpath upwards for a device with matching sysfs attribute values. |
e7c39acb | 212 | Up to five <option>ATTRS</option> keys can be specified per rule, but all of them |
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213 | must match on the same device. Trailing whitespace in the attribute values is ignored, |
214 | if the specified match value does not contain trailing whitespace itself.</para> | |
7b86ada7 KS |
215 | </listitem> |
216 | </varlistentry> | |
217 | ||
218 | <varlistentry> | |
03b24b71 | 219 | <term><option>ENV{<replaceable>key</replaceable>}</option></term> |
7b86ada7 | 220 | <listitem> |
03b24b71 | 221 | <para>Match against the value of an environment variable. Up to five <option>ENV</option> |
02adc0cb KS |
222 | keys can be specified per rule. Depending on the type of operator, this key is also used |
223 | to export a variable to the environment.</para> | |
7b86ada7 KS |
224 | </listitem> |
225 | </varlistentry> | |
226 | ||
953249a3 KS |
227 | <varlistentry> |
228 | <term><option>TEST{<replaceable>octal mode mask</replaceable>}</option></term> | |
229 | <listitem> | |
230 | <para>Test the existence of a file. An octal mode mask can be specified | |
231 | if needed.</para> | |
232 | </listitem> | |
233 | </varlistentry> | |
234 | ||
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235 | <varlistentry> |
236 | <term><option>PROGRAM</option></term> | |
237 | <listitem> | |
238 | <para>Execute external program. The key is true, if the program returns | |
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239 | with exit code zero. The whole event environment is available to the |
240 | executed program. The program's output printed to stdout, is available in | |
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241 | the RESULT key.</para> |
242 | </listitem> | |
243 | </varlistentry> | |
244 | ||
245 | <varlistentry> | |
246 | <term><option>RESULT</option></term> | |
247 | <listitem> | |
248 | <para>Match the returned string of the last PROGRAM call. This key can | |
249 | be used in the same or in any later rule after a PROGRAM call.</para> | |
250 | </listitem> | |
251 | </varlistentry> | |
252 | </variablelist> | |
253 | ||
254 | <para>Most of the fields support a shell style pattern matching. The following | |
255 | pattern characters are supported:</para> | |
256 | <variablelist> | |
257 | <varlistentry> | |
258 | <term><option>*</option></term> | |
259 | <listitem> | |
260 | <para>Matches zero, or any number of characters.</para> | |
261 | </listitem> | |
262 | </varlistentry> | |
263 | <varlistentry> | |
264 | <term><option>?</option></term> | |
265 | <listitem> | |
266 | <para>Matches any single character.</para> | |
267 | </listitem> | |
268 | </varlistentry> | |
269 | <varlistentry> | |
270 | <term><option>[]</option></term> | |
271 | <listitem> | |
33a570f3 | 272 | <para>Matches any single character specified within the brackets. For |
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273 | example, the pattern string 'tty[SR]' would match either 'ttyS' or 'ttyR'. |
274 | Ranges are also supported within this match with the '-' character. | |
275 | For example, to match on the range of all digits, the pattern [0-9] would | |
276 | be used. If the first character following the '[' is a '!', any characters | |
277 | not enclosed are matched.</para> | |
278 | </listitem> | |
279 | </varlistentry> | |
280 | </variablelist> | |
281 | ||
282 | <para>The following keys can get values assigned:</para> | |
283 | <variablelist> | |
284 | <varlistentry> | |
285 | <term><option>NAME</option></term> | |
286 | <listitem> | |
fabd8709 KS |
287 | <para>The name of the node to be created, or the name the network interface |
288 | should be renamed to. Only one rule can set the node name, all later rules with | |
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289 | a NAME key will be ignored.</para> |
290 | </listitem> | |
291 | </varlistentry> | |
292 | ||
293 | <varlistentry> | |
294 | <term><option>SYMLINK</option></term> | |
295 | <listitem> | |
296 | <para>The name of a symlink targeting the node. Every matching rule can add | |
297 | this value to the list of symlinks to be created along with the device node. | |
298 | Multiple symlinks may be specified by separating the names by the space | |
299 | character.</para> | |
300 | </listitem> | |
301 | </varlistentry> | |
302 | ||
303 | <varlistentry> | |
304 | <term><option>OWNER, GROUP, MODE</option></term> | |
305 | <listitem> | |
fabd8709 | 306 | <para>The permissions for the device node. Every specified value overwrites |
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307 | the compiled-in default value.</para> |
308 | </listitem> | |
309 | </varlistentry> | |
310 | ||
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311 | <varlistentry> |
312 | <term><option>ATTR{<replaceable>key</replaceable>}</option></term> | |
313 | <listitem> | |
314 | <para>The value that should be written to a sysfs attribute of the | |
315 | event device. Depending on the type of operator, this key is also | |
316 | used to match against the value of a sysfs attribute.</para> | |
317 | </listitem> | |
318 | </varlistentry> | |
319 | ||
7b86ada7 KS |
320 | <varlistentry> |
321 | <term><option>ENV{<replaceable>key</replaceable>}</option></term> | |
322 | <listitem> | |
02adc0cb KS |
323 | <para>Export a variable to the environment. Depending on the type of operator, |
324 | this key is also to match against an environment variable.</para> | |
7b86ada7 KS |
325 | </listitem> |
326 | </varlistentry> | |
327 | ||
328 | <varlistentry> | |
329 | <term><option>RUN</option></term> | |
330 | <listitem> | |
331 | <para>Add a program to the list of programs to be executed for a specific | |
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332 | device. This can only be used for very short running tasks. Running an |
333 | event process for a long period of time may block all further events for | |
334 | this or a dependent device. Long running tasks need to be immediately | |
335 | detached from the event process itself.</para> | |
7b86ada7 KS |
336 | </listitem> |
337 | </varlistentry> | |
338 | ||
339 | <varlistentry> | |
340 | <term><option>LABEL</option></term> | |
341 | <listitem> | |
342 | <para>Named label where a GOTO can jump to.</para> | |
343 | </listitem> | |
344 | </varlistentry> | |
345 | ||
346 | <varlistentry> | |
347 | <term><option>GOTO</option></term> | |
348 | <listitem> | |
a2a7f7d7 | 349 | <para>Jumps to the next LABEL with a matching name</para> |
7b86ada7 KS |
350 | </listitem> |
351 | </varlistentry> | |
352 | ||
353 | <varlistentry> | |
354 | <term><option>IMPORT{<replaceable>type</replaceable>}</option></term> | |
355 | <listitem> | |
53fc01d5 BK |
356 | <para>Import a set of variables into the event environment, |
357 | depending on <replaceable>type</replaceable>:</para> | |
358 | <variablelist> | |
359 | <varlistentry> | |
360 | <term><option>program</option></term> | |
361 | <listitem> | |
362 | <para>Execute an external program specified as the assigned value and | |
363 | import its output, which must be in environment key format.</para> | |
364 | </listitem> | |
365 | </varlistentry> | |
366 | <varlistentry> | |
367 | <term><option>file</option></term> | |
368 | <listitem> | |
369 | <para>Import a text file specified as the assigned value, which must be in | |
370 | environment key format.</para> | |
371 | </listitem> | |
372 | </varlistentry> | |
373 | <varlistentry> | |
374 | <term><option>parent</option></term> | |
375 | <listitem> | |
376 | <para>Import the stored keys from the parent device by reading | |
377 | the database entry of the parent device. The value assigned to | |
378 | <option>IMPORT{parent}</option> is used as a filter of key names | |
379 | to import (with the same shell-style pattern matching used for | |
380 | comparisons).</para> | |
381 | </listitem> | |
382 | </varlistentry> | |
383 | </variablelist> | |
384 | <para>If no option is given, udev will choose between <option>program</option> | |
7f723806 | 385 | and <option>file</option> based on the executable bit of the file |
53fc01d5 | 386 | permissions.</para> |
7b86ada7 KS |
387 | </listitem> |
388 | </varlistentry> | |
389 | ||
390 | <varlistentry> | |
391 | <term><option>WAIT_FOR_SYSFS</option></term> | |
392 | <listitem> | |
03b24b71 KS |
393 | <para>Wait for the specified sysfs file of the device to be created. Can be used |
394 | to fight against kernel sysfs timing issues.</para> | |
7b86ada7 KS |
395 | </listitem> |
396 | </varlistentry> | |
397 | ||
398 | <varlistentry> | |
399 | <term><option>OPTIONS</option></term> | |
400 | <listitem> | |
7a17ca7e KS |
401 | <para>Rule and device options:</para> |
402 | <variablelist> | |
403 | <varlistentry> | |
404 | <term><option>last_rule</option></term> | |
405 | <listitem> | |
406 | <para>Stops further rules application. No later rules will have | |
407 | any effect.</para> | |
408 | </listitem> | |
409 | </varlistentry> | |
410 | <varlistentry> | |
411 | <term><option>ignore_device</option></term> | |
412 | <listitem> | |
413 | <para>Ignore this event completely.</para> | |
414 | </listitem> | |
415 | </varlistentry> | |
416 | <varlistentry> | |
417 | <term><option>ignore_remove</option></term> | |
418 | <listitem> | |
419 | <para>Ignore any later remove event for this device. This may be useful | |
420 | as a workaround for broken device drivers.</para> | |
421 | </listitem> | |
422 | </varlistentry> | |
423 | <varlistentry> | |
424 | <term><option>link_priority=<replaceable>value</replaceable></option></term> | |
425 | <listitem> | |
426 | <para>Specify the priority of the created symlinks. Devices with higher | |
427 | priorities overwrite existing symlinks of other devices.</para> | |
428 | </listitem> | |
429 | </varlistentry> | |
430 | <varlistentry> | |
431 | <term><option>all_partitions</option></term> | |
432 | <listitem> | |
433 | <para>Create the device nodes for all available partitions of a block device. | |
434 | This may be useful for removable media devices where media changes are not | |
435 | detected.</para> | |
436 | </listitem> | |
437 | </varlistentry> | |
438 | </variablelist> | |
7b86ada7 KS |
439 | </listitem> |
440 | </varlistentry> | |
441 | </variablelist> | |
442 | ||
443 | <para>The <option>NAME</option>, <option>SYMLINK</option>, <option>PROGRAM</option>, | |
864412e0 AB |
444 | <option>OWNER</option>, <option>GROUP</option> and <option>RUN</option> |
445 | fields support simple printf-like string substitutions. The <option>RUN</option> | |
446 | format chars gets applied after all rules have been processed, right before the program | |
447 | is executed. It allows the use of the complete environment set by earlier matching | |
448 | rules. For all other fields, substitutions are applied while the individual rule is | |
449 | being processed. The available substitutions are:</para> | |
7b86ada7 KS |
450 | <variablelist> |
451 | <varlistentry> | |
03b24b71 | 452 | <term><option>$kernel</option>, <option>%k</option></term> |
7b86ada7 KS |
453 | <listitem> |
454 | <para>The kernel name for this device.</para> | |
455 | </listitem> | |
456 | </varlistentry> | |
457 | ||
7b86ada7 | 458 | <varlistentry> |
03b24b71 | 459 | <term><option>$number</option>, <option>%n</option></term> |
7b86ada7 KS |
460 | <listitem> |
461 | <para>The kernel number for this device. For example, 'sda3' has | |
462 | kernel number of '3'</para> | |
463 | </listitem> | |
464 | </varlistentry> | |
465 | ||
466 | <varlistentry> | |
03b24b71 | 467 | <term><option>$devpath</option>, <option>%p</option></term> |
7b86ada7 KS |
468 | <listitem> |
469 | <para>The devpath of the device.</para> | |
470 | </listitem> | |
471 | </varlistentry> | |
472 | ||
473 | <varlistentry> | |
03b24b71 KS |
474 | <term><option>$id</option>, <option>%b</option></term> |
475 | <listitem> | |
476 | <para>The name of the device matched while searching the devpath upwards for | |
4febf7f0 | 477 | <option>SUBSYSTEMS</option>, <option>KERNELS</option>, <option>DRIVERS</option> and <option>ATTRS</option>. |
03b24b71 KS |
478 | </para> |
479 | </listitem> | |
480 | </varlistentry> | |
481 | ||
482 | <varlistentry> | |
95776dc6 | 483 | <term><option>$attr{<replaceable>file</replaceable>}</option>, <option>%s{<replaceable>file</replaceable>}</option></term> |
7b86ada7 | 484 | <listitem> |
4febf7f0 KS |
485 | <para>The value of a sysfs attribute found at the device, where |
486 | all keys of the rule have matched. If the matching device does not have | |
487 | such an attribute, all devices along the chain of parents are searched | |
488 | for a matching attribute. | |
489 | If the attribute is a symlink, the last element of the symlink target is | |
490 | returned as the value.</para> | |
7b86ada7 KS |
491 | </listitem> |
492 | </varlistentry> | |
493 | ||
494 | <varlistentry> | |
03b24b71 | 495 | <term><option>$env{<replaceable>key</replaceable>}</option>, <option>%E{<replaceable>key</replaceable>}</option></term> |
7b86ada7 KS |
496 | <listitem> |
497 | <para>The value of an environment variable.</para> | |
498 | </listitem> | |
499 | </varlistentry> | |
500 | ||
501 | <varlistentry> | |
03b24b71 | 502 | <term><option>$major</option>, <option>%M</option></term> |
7b86ada7 KS |
503 | <listitem> |
504 | <para>The kernel major number for the device.</para> | |
505 | </listitem> | |
506 | </varlistentry> | |
507 | ||
508 | <varlistentry> | |
7f723806 | 509 | <term><option>$minor</option>, <option>%m</option></term> |
7b86ada7 KS |
510 | <listitem> |
511 | <para>The kernel minor number for the device.</para> | |
512 | </listitem> | |
513 | </varlistentry> | |
514 | ||
515 | <varlistentry> | |
03b24b71 | 516 | <term><option>$result</option>, <option>%c</option></term> |
7b86ada7 KS |
517 | <listitem> |
518 | <para>The string returned by the external program requested with PROGRAM. | |
519 | A single part of the string, separated by a space character may be selected | |
520 | by specifying the part number as an attribute: <option>%c{N}</option>. | |
521 | If the number is followed by the '+' char this part plus all remaining parts | |
522 | of the result string are substituted: <option>%c{N+}</option></para> | |
523 | </listitem> | |
524 | </varlistentry> | |
525 | ||
7b86ada7 | 526 | <varlistentry> |
03b24b71 | 527 | <term><option>$parent</option>, <option>%P</option></term> |
7b86ada7 KS |
528 | <listitem> |
529 | <para>The node name of the parent device.</para> | |
530 | </listitem> | |
531 | </varlistentry> | |
532 | ||
533 | <varlistentry> | |
03b24b71 | 534 | <term><option>$root</option>, <option>%r</option></term> |
7b86ada7 KS |
535 | <listitem> |
536 | <para>The udev_root value.</para> | |
537 | </listitem> | |
538 | </varlistentry> | |
539 | ||
5e9eb88f KS |
540 | <varlistentry> |
541 | <term><option>$sys</option>, <option>%S</option></term> | |
542 | <listitem> | |
543 | <para>The sysfs mount point.</para> | |
544 | </listitem> | |
545 | </varlistentry> | |
546 | ||
7b86ada7 | 547 | <varlistentry> |
03b24b71 | 548 | <term><option>$tempnode</option>, <option>%N</option></term> |
7b86ada7 KS |
549 | <listitem> |
550 | <para>The name of a created temporary device node to provide access to | |
551 | the device from a external program before the real node is created.</para> | |
552 | </listitem> | |
553 | </varlistentry> | |
554 | ||
555 | <varlistentry> | |
556 | <term><option>%%</option></term> | |
557 | <listitem> | |
558 | <para>The '%' character itself.</para> | |
559 | </listitem> | |
560 | </varlistentry> | |
561 | ||
562 | <varlistentry> | |
563 | <term><option>$$</option></term> | |
564 | <listitem> | |
565 | <para>The '$' character itself.</para> | |
566 | </listitem> | |
567 | </varlistentry> | |
568 | </variablelist> | |
569 | <para>The count of characters to be substituted may be limited by specifying | |
570 | the format length value. For example, '%3s{file}' will only | |
571 | insert the first three characters of the sysfs attribute</para> | |
572 | </refsect2> | |
573 | </refsect1> | |
574 | ||
7b86ada7 KS |
575 | <refsect1><title>AUTHOR</title> |
576 | <para>Written by Greg Kroah-Hartman <email>greg@kroah.com</email> and | |
577 | Kay Sievers <email>kay.sievers@vrfy.org</email>. With much help from | |
578 | Dan Stekloff <email>dsteklof@us.ibm.com</email> and many others.</para> | |
579 | </refsect1> | |
580 | ||
581 | <refsect1> | |
582 | <title>SEE ALSO</title> | |
583 | <para><citerefentry> | |
2c769419 | 584 | <refentrytitle>udevd</refentrytitle><manvolnum>8</manvolnum> |
7b86ada7 KS |
585 | </citerefentry>, |
586 | <citerefentry> | |
587 | <refentrytitle>udevinfo</refentrytitle><manvolnum>8</manvolnum> | |
588 | </citerefentry>, | |
7b86ada7 KS |
589 | <citerefentry> |
590 | <refentrytitle>udevmonitor</refentrytitle><manvolnum>8</manvolnum> | |
591 | </citerefentry></para> | |
592 | </refsect1> | |
593 | </refentry> | |
594 | </section> | |
595 | </article> |