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7b86ada7 | 1 | <?xml version='1.0'?> |
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2 | <?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"?> |
3 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | |
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4 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
5 | ||
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6 | <refentry id="udev"> |
7 | <refentryinfo> | |
7b86ada7 | 8 | <title>udev</title> |
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9 | <productname>systemd</productname> |
10 | <authorgroup> | |
11 | <author> | |
12 | <contrib>Developer</contrib> | |
13 | <firstname>Greg</firstname> | |
14 | <surname>Kroah-Hartmann</surname> | |
15 | <email>greg@kroah.com</email> | |
16 | </author> | |
17 | <author> | |
18 | <contrib>Developer</contrib> | |
19 | <firstname>Kay</firstname> | |
20 | <surname>Sievers</surname> | |
21 | <email>kay@vrfy.org</email> | |
22 | </author> | |
23 | </authorgroup> | |
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24 | </refentryinfo> |
25 | ||
26 | <refmeta> | |
27 | <refentrytitle>udev</refentrytitle> | |
28 | <manvolnum>7</manvolnum> | |
29 | </refmeta> | |
30 | ||
31 | <refnamediv> | |
32 | <refname>udev</refname> | |
33 | <refpurpose>Linux dynamic device management</refpurpose> | |
34 | </refnamediv> | |
35 | ||
36 | <refsect1><title>Description</title> | |
37 | <para>udev supplies the system software with device events, manages permissions | |
38 | of device nodes and may create additional symlinks in the <filename>/dev</filename> | |
39 | directory, or renames network interfaces. The kernel usually just assigns unpredictable | |
40 | device names based on the order of discovery. Meaningful symlinks or network device | |
41 | names provide a way to reliably identify devices based on their properties or | |
42 | current configuration.</para> | |
43 | ||
b79f817b | 44 | <para>The udev daemon, <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle> |
0e4fa2ab | 45 | <manvolnum>8</manvolnum></citerefentry>, receives device uevents directly from |
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46 | the kernel whenever a device is added or removed from the system, or it changes its |
47 | state. When udev receives a device event, it matches its configured set of rules | |
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48 | against various device attributes to identify the device. Rules that match may |
49 | provide additional device information to be stored in the udev database or | |
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50 | to be used to create meaningful symlink names.</para> |
51 | ||
0e846301 | 52 | <para>All device information udev processes is stored in the udev database and |
63749b1a | 53 | sent out to possible event subscribers. Access to all stored data and the event |
17fd0f60 | 54 | sources is provided by the library libudev.</para> |
63749b1a KS |
55 | </refsect1> |
56 | ||
6ec0ac43 | 57 | <refsect1><title>Rules files</title> |
63749b1a | 58 | <para>The udev rules are read from the files located in the |
12a362be | 59 | system rules directory <filename>/usr/lib/udev/rules.d</filename>, |
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60 | the volatile runtime directory <filename>/run/udev/rules.d</filename> |
61 | and the local administration directory <filename>/etc/udev/rules.d</filename>. | |
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62 | All rules files are collectively sorted and processed in lexical order, |
63 | regardless of the directories in which they live. However, files with | |
e9dd9f95 | 64 | identical filenames replace each other. Files in <filename>/etc</filename> |
91418155 | 65 | have the highest priority, files in <filename>/run</filename> take precedence |
1021e6df | 66 | over files with the same name in <filename>/lib</filename>. This can be |
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67 | used to override a system-supplied rules file with a local file if needed; |
68 | a symlink in <filename>/etc</filename> with the same name as a rules file in | |
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69 | <filename>/lib</filename>, pointing to <filename>/dev/null</filename>, |
70 | disables the rules file entirely.</para> | |
63749b1a | 71 | |
c3cba32f MW |
72 | <para>Rule files must have the extension <filename>.rules</filename>; other |
73 | extensions are ignored.</para> | |
63749b1a | 74 | |
feedf8f3 | 75 | <para>Every line in the rules file contains at least one key-value pair. |
909f413d | 76 | Except for empty lines or lines beginning with <literal>#</literal>, which are ignored. |
bb31a4ac | 77 | There are two kinds of keys: match and assignment. |
6ec0ac43 TG |
78 | If all match keys match against their values, the rule gets applied and the |
79 | assignment keys get the specified values assigned.</para> | |
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80 | |
81 | <para>A matching rule may rename a network interface, add symlinks | |
82 | pointing to the device node, or run a specified program as part of | |
83 | the event handling.</para> | |
84 | ||
55f5037c MW |
85 | <para>A rule consists of a comma-separated list of one or more key-value pairs. |
86 | Each key has a distinct operation, depending on the used operator. Valid | |
63749b1a KS |
87 | operators are:</para> |
88 | <variablelist> | |
89 | <varlistentry> | |
6b76fa66 | 90 | <term><literal>==</literal></term> |
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91 | <listitem> |
92 | <para>Compare for equality.</para> | |
93 | </listitem> | |
94 | </varlistentry> | |
95 | ||
96 | <varlistentry> | |
6b76fa66 | 97 | <term><literal>!=</literal></term> |
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98 | <listitem> |
99 | <para>Compare for inequality.</para> | |
100 | </listitem> | |
101 | </varlistentry> | |
102 | ||
103 | <varlistentry> | |
6b76fa66 | 104 | <term><literal>=</literal></term> |
63749b1a | 105 | <listitem> |
0e846301 | 106 | <para>Assign a value to a key. Keys that represent a list are reset |
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107 | and only this single value is assigned.</para> |
108 | </listitem> | |
109 | </varlistentry> | |
110 | ||
111 | <varlistentry> | |
6b76fa66 | 112 | <term><literal>+=</literal></term> |
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113 | <listitem> |
114 | <para>Add the value to a key that holds a list of entries.</para> | |
115 | </listitem> | |
116 | </varlistentry> | |
117 | ||
118 | <varlistentry> | |
6b76fa66 | 119 | <term><literal>:=</literal></term> |
63749b1a | 120 | <listitem> |
2bf11540 | 121 | <para>Assign a value to a key finally; disallow any later changes.</para> |
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122 | </listitem> |
123 | </varlistentry> | |
124 | </variablelist> | |
125 | ||
126 | <para>The following key names can be used to match against device properties. | |
127 | Some of the keys also match against properties of the parent devices in sysfs, | |
128 | not only the device that has generated the event. If multiple keys that match | |
129 | a parent device are specified in a single rule, all these keys must match at | |
130 | one and the same parent device.</para> | |
ccc9a4f9 | 131 | <variablelist class='udev-directives'> |
63749b1a | 132 | <varlistentry> |
909f413d | 133 | <term><varname>ACTION</varname></term> |
63749b1a KS |
134 | <listitem> |
135 | <para>Match the name of the event action.</para> | |
136 | </listitem> | |
137 | </varlistentry> | |
138 | ||
139 | <varlistentry> | |
909f413d | 140 | <term><varname>DEVPATH</varname></term> |
63749b1a KS |
141 | <listitem> |
142 | <para>Match the devpath of the event device.</para> | |
143 | </listitem> | |
144 | </varlistentry> | |
145 | ||
146 | <varlistentry> | |
909f413d | 147 | <term><varname>KERNEL</varname></term> |
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148 | <listitem> |
149 | <para>Match the name of the event device.</para> | |
150 | </listitem> | |
151 | </varlistentry> | |
152 | ||
153 | <varlistentry> | |
909f413d | 154 | <term><varname>NAME</varname></term> |
63749b1a | 155 | <listitem> |
220893b3 KS |
156 | <para>Match the name of a network interface. It can be used once the |
157 | NAME key has been set in one of the preceding rules.</para> | |
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158 | </listitem> |
159 | </varlistentry> | |
160 | ||
161 | <varlistentry> | |
909f413d | 162 | <term><varname>SYMLINK</varname></term> |
63749b1a KS |
163 | <listitem> |
164 | <para>Match the name of a symlink targeting the node. It can | |
165 | be used once a SYMLINK key has been set in one of the preceding | |
166 | rules. There may be multiple symlinks; only one needs to match. | |
167 | </para> | |
168 | </listitem> | |
169 | </varlistentry> | |
170 | ||
171 | <varlistentry> | |
909f413d | 172 | <term><varname>SUBSYSTEM</varname></term> |
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173 | <listitem> |
174 | <para>Match the subsystem of the event device.</para> | |
175 | </listitem> | |
176 | </varlistentry> | |
177 | <varlistentry> | |
909f413d | 178 | <term><varname>DRIVER</varname></term> |
63749b1a | 179 | <listitem> |
2e7f69eb | 180 | <para>Match the driver name of the event device. Only set this key for devices |
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181 | which are bound to a driver at the time the event is generated.</para> |
182 | </listitem> | |
183 | </varlistentry> | |
184 | <varlistentry> | |
909f413d | 185 | <term><varname>ATTR{<replaceable>filename</replaceable>}</varname></term> |
63749b1a KS |
186 | <listitem> |
187 | <para>Match sysfs attribute values of the event device. Trailing | |
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188 | whitespace in the attribute values is ignored unless the specified match |
189 | value itself contains trailing whitespace. | |
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190 | </para> |
191 | </listitem> | |
192 | </varlistentry> | |
193 | ||
194 | <varlistentry> | |
909f413d | 195 | <term><varname>KERNELS</varname></term> |
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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> |
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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> |
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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 |
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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> | |
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222 | </listitem> |
223 | </varlistentry> | |
224 | ||
7df0ed83 | 225 | <varlistentry> |
909f413d | 226 | <term><varname>TAGS</varname></term> |
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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> |
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234 | <listitem> |
235 | <para>Match against a device property value.</para> | |
236 | </listitem> | |
237 | </varlistentry> | |
238 | ||
239 | <varlistentry> | |
909f413d | 240 | <term><varname>TAG</varname></term> |
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241 | <listitem> |
242 | <para>Match against a device tag.</para> | |
243 | </listitem> | |
244 | </varlistentry> | |
245 | ||
246 | <varlistentry> | |
909f413d | 247 | <term><varname>TEST{<replaceable>octal mode mask</replaceable>}</varname></term> |
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248 | <listitem> |
249 | <para>Test the existence of a file. An octal mode mask can be specified | |
250 | if needed.</para> | |
251 | </listitem> | |
252 | </varlistentry> | |
253 | ||
254 | <varlistentry> | |
909f413d | 255 | <term><varname>PROGRAM</varname></term> |
63749b1a | 256 | <listitem> |
2e9820e3 MW |
257 | <para>Execute a program to determine whether there |
258 | is a match; the key is true if the program returns | |
63749b1a | 259 | successfully. The device properties are made available to the |
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260 | executed program in the environment. The program's stdout |
261 | is available in the RESULT key.</para> | |
b45f770f | 262 | <para>This can only be used for very short-running foreground tasks. For details |
909f413d | 263 | see <varname>RUN</varname>.</para> |
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264 | </listitem> |
265 | </varlistentry> | |
266 | ||
267 | <varlistentry> | |
909f413d | 268 | <term><varname>RESULT</varname></term> |
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269 | <listitem> |
270 | <para>Match the returned string of the last PROGRAM call. This key can | |
271 | be used in the same or in any later rule after a PROGRAM call.</para> | |
272 | </listitem> | |
273 | </varlistentry> | |
274 | </variablelist> | |
275 | ||
401e59e9 | 276 | <para>Most of the fields support shell-style pattern matching. The following |
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277 | pattern characters are supported:</para> |
278 | <variablelist> | |
279 | <varlistentry> | |
6b76fa66 | 280 | <term><literal>*</literal></term> |
63749b1a | 281 | <listitem> |
954e9c52 | 282 | <para>Matches zero or more characters.</para> |
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283 | </listitem> |
284 | </varlistentry> | |
285 | <varlistentry> | |
6b76fa66 | 286 | <term><literal>?</literal></term> |
63749b1a KS |
287 | <listitem> |
288 | <para>Matches any single character.</para> | |
289 | </listitem> | |
290 | </varlistentry> | |
291 | <varlistentry> | |
6b76fa66 | 292 | <term><literal>[]</literal></term> |
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293 | <listitem> |
294 | <para>Matches any single character specified within the brackets. For | |
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295 | example, the pattern string <literal>tty[SR]</literal> |
296 | would match either <literal>ttyS</literal> or <literal>ttyR</literal>. | |
297 | Ranges are also supported via the <literal>-</literal> character. | |
2c47027b | 298 | For example, to match on the range of all digits, the pattern [0-9] could |
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299 | be used. If the first character following the <literal>[</literal> is a |
300 | <literal>!</literal>, any characters not enclosed are matched.</para> | |
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301 | </listitem> |
302 | </varlistentry> | |
303 | </variablelist> | |
304 | ||
305 | <para>The following keys can get values assigned:</para> | |
ccc9a4f9 | 306 | <variablelist class='udev-directives'> |
63749b1a | 307 | <varlistentry> |
909f413d | 308 | <term><varname>NAME</varname></term> |
63749b1a | 309 | <listitem> |
220893b3 | 310 | <para>The name to use for a network interface. The name of a device node |
bb31a4ac | 311 | cannot be changed by udev, only additional symlinks can be created.</para> |
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312 | </listitem> |
313 | </varlistentry> | |
314 | ||
315 | <varlistentry> | |
909f413d | 316 | <term><varname>SYMLINK</varname></term> |
63749b1a | 317 | <listitem> |
933b5623 | 318 | <para>The name of a symlink targeting the node. Every matching rule adds |
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319 | this value to the list of symlinks to be created.</para> |
320 | <para>The set of characters to name a symlink is limited. Allowed | |
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321 | characters are <literal>0-9A-Za-z#+-.:=@_/</literal>, valid UTF-8 character |
322 | sequences, and <literal>\x00</literal> hex encoding. All other | |
323 | characters are replaced by a <literal>_</literal> character.</para> | |
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324 | <para>Multiple symlinks may be specified by separating the names by the |
325 | space character. In case multiple devices claim the same name, the link | |
326 | always points to the device with the highest link_priority. If the current | |
327 | device goes away, the links are re-evaluated and the device with the | |
328 | next highest link_priority becomes the owner of the link. If no | |
329 | link_priority is specified, the order of the devices (and which one of | |
330 | them owns the link) is undefined.</para> | |
331 | <para>Symlink names must never conflict with the kernel's default device | |
332 | node names, as that would result in unpredictable behavior. | |
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333 | </para> |
334 | </listitem> | |
335 | </varlistentry> | |
336 | ||
337 | <varlistentry> | |
909f413d | 338 | <term><varname>OWNER</varname>, <varname>GROUP</varname>, <varname>MODE</varname></term> |
63749b1a | 339 | <listitem> |
91418155 | 340 | <para>The permissions for the device node. Every specified value overrides |
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341 | the compiled-in default value.</para> |
342 | </listitem> | |
343 | </varlistentry> | |
344 | ||
345 | <varlistentry> | |
909f413d | 346 | <term><varname>ATTR{<replaceable>key</replaceable>}</varname></term> |
63749b1a KS |
347 | <listitem> |
348 | <para>The value that should be written to a sysfs attribute of the | |
349 | event device.</para> | |
350 | </listitem> | |
351 | </varlistentry> | |
352 | ||
353 | <varlistentry> | |
909f413d | 354 | <term><varname>ENV{<replaceable>key</replaceable>}</varname></term> |
63749b1a | 355 | <listitem> |
909f413d | 356 | <para>Set a device property value. Property names with a leading <literal>.</literal> |
ed9c5fb7 MW |
357 | are neither stored in the database nor exported to events or |
358 | external tools (run by, say, the PROGRAM match key).</para> | |
63749b1a KS |
359 | </listitem> |
360 | </varlistentry> | |
361 | ||
362 | <varlistentry> | |
909f413d | 363 | <term><varname>TAG</varname></term> |
63749b1a KS |
364 | <listitem> |
365 | <para>Attach a tag to a device. This is used to filter events for users | |
366 | of libudev's monitor functionality, or to enumerate a group of tagged | |
367 | devices. The implementation can only work efficiently if only a few | |
368 | tags are attached to a device. It is only meant to be used in | |
369 | contexts with specific device filter requirements, and not as a | |
370 | general-purpose flag. Excessive use might result in inefficient event | |
371 | handling.</para> | |
372 | </listitem> | |
373 | </varlistentry> | |
374 | ||
375 | <varlistentry> | |
909f413d | 376 | <term><varname>RUN{<replaceable>type</replaceable>}</varname></term> |
63749b1a | 377 | <listitem> |
08cbc57e TG |
378 | <para>Add a program to the list of programs to be executed after processing all the |
379 | rules for a specific event, depending on <literal>type</literal>:</para> | |
72c6cf8f TG |
380 | <variablelist> |
381 | <varlistentry> | |
382 | <term><literal>program</literal></term> | |
383 | <listitem> | |
384 | <para>Execute an external program specified as the assigned | |
385 | value. If no absolute path is given, the program is expected to live in | |
386 | /usr/lib/udev, otherwise the absolute path must be specified.</para> | |
387 | <para>This is the default if no <replaceable>type</replaceable> is | |
388 | specified.</para> | |
389 | </listitem> | |
390 | </varlistentry> | |
391 | <varlistentry> | |
392 | <term><literal>builtin</literal></term> | |
393 | <listitem> | |
909f413d | 394 | <para>As <varname>program</varname>, but use one of the built-in programs rather |
72c6cf8f TG |
395 | than an external one.</para> |
396 | </listitem> | |
397 | </varlistentry> | |
398 | </variablelist> | |
399 | <para>The program name and following arguments are separated by spaces. | |
400 | Single quotes can be used to specify arguments with spaces.</para> | |
b45f770f | 401 | <para>This can only be used for very short-running foreground tasks. Running an |
2b76eb68 | 402 | event process for a long period of time may block all further events for |
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403 | this or a dependent device.</para> |
404 | <para>Starting daemons or other long running processes is not appropriate | |
405 | for udev; the forked processes, detached or not, will be unconditionally | |
406 | killed after the event handling has finished.</para> | |
63749b1a KS |
407 | </listitem> |
408 | </varlistentry> | |
409 | ||
410 | <varlistentry> | |
909f413d | 411 | <term><varname>LABEL</varname></term> |
63749b1a | 412 | <listitem> |
c24dfc80 | 413 | <para>A named label to which a GOTO may jump.</para> |
63749b1a KS |
414 | </listitem> |
415 | </varlistentry> | |
416 | ||
417 | <varlistentry> | |
909f413d | 418 | <term><varname>GOTO</varname></term> |
63749b1a | 419 | <listitem> |
2f16de29 | 420 | <para>Jumps to the next LABEL with a matching name.</para> |
63749b1a KS |
421 | </listitem> |
422 | </varlistentry> | |
423 | ||
424 | <varlistentry> | |
909f413d | 425 | <term><varname>IMPORT{<replaceable>type</replaceable>}</varname></term> |
63749b1a KS |
426 | <listitem> |
427 | <para>Import a set of variables as device properties, | |
6b76fa66 | 428 | depending on <literal>type</literal>:</para> |
63749b1a KS |
429 | <variablelist> |
430 | <varlistentry> | |
6b76fa66 | 431 | <term><literal>program</literal></term> |
63749b1a KS |
432 | <listitem> |
433 | <para>Execute an external program specified as the assigned value and | |
434 | import its output, which must be in environment key | |
435 | format. Path specification, command/argument separation, | |
909f413d | 436 | and quoting work like in <varname>RUN</varname>.</para> |
63749b1a KS |
437 | </listitem> |
438 | </varlistentry> | |
439 | <varlistentry> | |
72c6cf8f TG |
440 | <term><literal>builtin</literal></term> |
441 | <listitem> | |
909f413d ZJS |
442 | <para>Similar to <literal>program</literal>, but use one of the |
443 | built-in programs rather than an external one.</para> | |
72c6cf8f TG |
444 | </listitem> |
445 | </varlistentry> | |
446 | <varlistentry> | |
6b76fa66 | 447 | <term><literal>file</literal></term> |
63749b1a | 448 | <listitem> |
b6a49cd6 MW |
449 | <para>Import a text file specified as the assigned value, the content |
450 | of which must be in environment key format.</para> | |
63749b1a KS |
451 | </listitem> |
452 | </varlistentry> | |
453 | <varlistentry> | |
6b76fa66 | 454 | <term><literal>db</literal></term> |
63749b1a KS |
455 | <listitem> |
456 | <para>Import a single property specified as the assigned value from the | |
457 | current device database. This works only if the database is already populated | |
458 | by an earlier event.</para> | |
459 | </listitem> | |
460 | </varlistentry> | |
c4f6dcc4 | 461 | <varlistentry> |
6b76fa66 | 462 | <term><literal>cmdline</literal></term> |
c4f6dcc4 | 463 | <listitem> |
ad9c70a8 | 464 | <para>Import a single property from the kernel command line. For simple flags |
909f413d | 465 | the value of the property is set to <literal>1</literal>.</para> |
c4f6dcc4 KS |
466 | </listitem> |
467 | </varlistentry> | |
63749b1a | 468 | <varlistentry> |
6b76fa66 | 469 | <term><literal>parent</literal></term> |
63749b1a KS |
470 | <listitem> |
471 | <para>Import the stored keys from the parent device by reading | |
472 | the database entry of the parent device. The value assigned to | |
473 | <option>IMPORT{parent}</option> is used as a filter of key names | |
474 | to import (with the same shell-style pattern matching used for | |
475 | comparisons).</para> | |
476 | </listitem> | |
477 | </varlistentry> | |
478 | </variablelist> | |
b45f770f KS |
479 | <para>This can only be used for very short-running foreground tasks. For details |
480 | see <option>RUN</option>.</para> | |
63749b1a KS |
481 | </listitem> |
482 | </varlistentry> | |
483 | ||
484 | <varlistentry> | |
909f413d | 485 | <term><varname>WAIT_FOR</varname></term> |
63749b1a | 486 | <listitem> |
793681cb MW |
487 | <para>Wait for a file to become available or until a timeout of |
488 | 10 seconds expires. The path is relative to the sysfs device; | |
489 | if no path is specified, this waits for an attribute to appear.</para> | |
63749b1a KS |
490 | </listitem> |
491 | </varlistentry> | |
492 | ||
493 | <varlistentry> | |
909f413d | 494 | <term><varname>OPTIONS</varname></term> |
63749b1a KS |
495 | <listitem> |
496 | <para>Rule and device options:</para> | |
ccc9a4f9 | 497 | <variablelist class='udev-directives'> |
63749b1a KS |
498 | <varlistentry> |
499 | <term><option>link_priority=<replaceable>value</replaceable></option></term> | |
500 | <listitem> | |
501 | <para>Specify the priority of the created symlinks. Devices with higher | |
502 | priorities overwrite existing symlinks of other devices. The default is 0.</para> | |
503 | </listitem> | |
504 | </varlistentry> | |
505 | <varlistentry> | |
506 | <term><option>event_timeout=</option></term> | |
507 | <listitem> | |
933b5623 MW |
508 | <para>Number of seconds an event waits for operations to finish before |
509 | giving up and terminating itself.</para> | |
63749b1a KS |
510 | </listitem> |
511 | </varlistentry> | |
512 | <varlistentry> | |
513 | <term><option>string_escape=<replaceable>none|replace</replaceable></option></term> | |
514 | <listitem> | |
515 | <para>Usually control and other possibly unsafe characters are replaced | |
516 | in strings used for device naming. The mode of replacement can be specified | |
517 | with this option.</para> | |
518 | </listitem> | |
519 | </varlistentry> | |
9fa68615 KS |
520 | <varlistentry> |
521 | <term><option>static_node=</option></term> | |
522 | <listitem> | |
0fbda083 | 523 | <para>Apply the permissions specified in this rule to the static device node with |
84b6ad70 TG |
524 | the specified name. Also, for every tag specified in this rule, create a symlink |
525 | in the directory | |
526 | <filename>/run/udev/static_node-tags/<replaceable>tag</replaceable></filename> | |
527 | pointing at the static device node with the specified name. Static device node | |
528 | creation is performed by systemd-tmpfiles before systemd-udevd is started. The | |
529 | static nodes might not have a corresponding kernel device; they are used to | |
530 | trigger automatic kernel module loading when they are accessed.</para> | |
9fa68615 KS |
531 | </listitem> |
532 | </varlistentry> | |
63749b1a KS |
533 | <varlistentry> |
534 | <term><option>watch</option></term> | |
535 | <listitem> | |
620da34d MW |
536 | <para>Watch the device node with inotify; when the node is closed after being opened for |
537 | writing, a change uevent is synthesized.</para> | |
63749b1a KS |
538 | </listitem> |
539 | </varlistentry> | |
3b529da4 KS |
540 | <varlistentry> |
541 | <term><option>nowatch</option></term> | |
542 | <listitem> | |
543 | <para>Disable the watching of a device node with inotify.</para> | |
544 | </listitem> | |
545 | </varlistentry> | |
63749b1a KS |
546 | </variablelist> |
547 | </listitem> | |
548 | </varlistentry> | |
549 | </variablelist> | |
550 | ||
909f413d ZJS |
551 | <para>The <varname>NAME</varname>, <varname>SYMLINK</varname>, <varname>PROGRAM</varname>, |
552 | <varname>OWNER</varname>, <varname>GROUP</varname>, <varname>MODE</varname> and <varname>RUN</varname> | |
553 | fields support simple string substitutions. The <varname>RUN</varname> | |
57e80484 MW |
554 | substitutions are performed after all rules have been processed, right before the program |
555 | is executed, allowing for the use of device properties set by earlier matching | |
556 | rules. For all other fields, substitutions are performed while the individual rule is | |
63749b1a | 557 | being processed. The available substitutions are:</para> |
ccc9a4f9 | 558 | <variablelist class='udev-directives'> |
63749b1a KS |
559 | <varlistentry> |
560 | <term><option>$kernel</option>, <option>%k</option></term> | |
561 | <listitem> | |
562 | <para>The kernel name for this device.</para> | |
563 | </listitem> | |
564 | </varlistentry> | |
565 | ||
566 | <varlistentry> | |
567 | <term><option>$number</option>, <option>%n</option></term> | |
568 | <listitem> | |
909f413d ZJS |
569 | <para>The kernel number for this device. For example, |
570 | <literal>sda3</literal> has kernel number <literal>3</literal>.</para> | |
63749b1a KS |
571 | </listitem> |
572 | </varlistentry> | |
573 | ||
574 | <varlistentry> | |
575 | <term><option>$devpath</option>, <option>%p</option></term> | |
576 | <listitem> | |
577 | <para>The devpath of the device.</para> | |
578 | </listitem> | |
579 | </varlistentry> | |
580 | ||
581 | <varlistentry> | |
582 | <term><option>$id</option>, <option>%b</option></term> | |
583 | <listitem> | |
584 | <para>The name of the device matched while searching the devpath upwards for | |
585 | <option>SUBSYSTEMS</option>, <option>KERNELS</option>, <option>DRIVERS</option> and <option>ATTRS</option>. | |
586 | </para> | |
587 | </listitem> | |
588 | </varlistentry> | |
589 | ||
590 | <varlistentry> | |
591 | <term><option>$driver</option></term> | |
592 | <listitem> | |
593 | <para>The driver name of the device matched while searching the devpath upwards for | |
594 | <option>SUBSYSTEMS</option>, <option>KERNELS</option>, <option>DRIVERS</option> and <option>ATTRS</option>. | |
595 | </para> | |
596 | </listitem> | |
597 | </varlistentry> | |
598 | ||
599 | <varlistentry> | |
600 | <term><option>$attr{<replaceable>file</replaceable>}</option>, <option>%s{<replaceable>file</replaceable>}</option></term> | |
601 | <listitem> | |
0e846301 | 602 | <para>The value of a sysfs attribute found at the device where |
63749b1a | 603 | all keys of the rule have matched. If the matching device does not have |
83184d00 | 604 | such an attribute, and a previous KERNELS, SUBSYSTEMS, DRIVERS, or |
f2db23cd | 605 | ATTRS test selected a parent device, then the attribute from that |
f61501b0 MW |
606 | parent device is used.</para> |
607 | <para>If the attribute is a symlink, the last element of the symlink target is | |
63749b1a KS |
608 | returned as the value.</para> |
609 | </listitem> | |
610 | </varlistentry> | |
611 | ||
612 | <varlistentry> | |
613 | <term><option>$env{<replaceable>key</replaceable>}</option>, <option>%E{<replaceable>key</replaceable>}</option></term> | |
614 | <listitem> | |
615 | <para>A device property value.</para> | |
616 | </listitem> | |
617 | </varlistentry> | |
618 | ||
619 | <varlistentry> | |
620 | <term><option>$major</option>, <option>%M</option></term> | |
621 | <listitem> | |
622 | <para>The kernel major number for the device.</para> | |
623 | </listitem> | |
624 | </varlistentry> | |
625 | ||
626 | <varlistentry> | |
627 | <term><option>$minor</option>, <option>%m</option></term> | |
628 | <listitem> | |
629 | <para>The kernel minor number for the device.</para> | |
630 | </listitem> | |
631 | </varlistentry> | |
632 | ||
633 | <varlistentry> | |
634 | <term><option>$result</option>, <option>%c</option></term> | |
635 | <listitem> | |
636 | <para>The string returned by the external program requested with PROGRAM. | |
21188522 | 637 | A single part of the string, separated by a space character, may be selected |
909f413d ZJS |
638 | by specifying the part number as an attribute: <literal>%c{N}</literal>. |
639 | If the number is followed by the <literal>+</literal> character, this part plus all remaining parts | |
640 | of the result string are substituted: <literal>%c{N+}</literal>.</para> | |
63749b1a KS |
641 | </listitem> |
642 | </varlistentry> | |
643 | ||
644 | <varlistentry> | |
645 | <term><option>$parent</option>, <option>%P</option></term> | |
646 | <listitem> | |
647 | <para>The node name of the parent device.</para> | |
648 | </listitem> | |
649 | </varlistentry> | |
650 | ||
651 | <varlistentry> | |
652 | <term><option>$name</option></term> | |
653 | <listitem> | |
220893b3 | 654 | <para>The current name of the device. If not changed by a rule, it is the |
63749b1a KS |
655 | name of the kernel device.</para> |
656 | </listitem> | |
657 | </varlistentry> | |
658 | ||
659 | <varlistentry> | |
660 | <term><option>$links</option></term> | |
661 | <listitem> | |
e8b5e4e5 | 662 | <para>A space-separated list of the current symlinks. The value is |
2d74bc75 | 663 | only set during a remove event or if an earlier rule assigned a value.</para> |
63749b1a KS |
664 | </listitem> |
665 | </varlistentry> | |
666 | ||
667 | <varlistentry> | |
668 | <term><option>$root</option>, <option>%r</option></term> | |
669 | <listitem> | |
670 | <para>The udev_root value.</para> | |
671 | </listitem> | |
672 | </varlistentry> | |
673 | ||
674 | <varlistentry> | |
675 | <term><option>$sys</option>, <option>%S</option></term> | |
676 | <listitem> | |
677 | <para>The sysfs mount point.</para> | |
678 | </listitem> | |
679 | </varlistentry> | |
680 | ||
681 | <varlistentry> | |
220893b3 | 682 | <term><option>$devnode</option>, <option>%N</option></term> |
63749b1a | 683 | <listitem> |
220893b3 | 684 | <para>The name of the device node.</para> |
63749b1a KS |
685 | </listitem> |
686 | </varlistentry> | |
687 | ||
688 | <varlistentry> | |
909f413d | 689 | <term><option>%%</option></term> |
63749b1a | 690 | <listitem> |
909f413d | 691 | <para>The <literal>%</literal> character itself.</para> |
63749b1a KS |
692 | </listitem> |
693 | </varlistentry> | |
694 | ||
695 | <varlistentry> | |
909f413d | 696 | <term><option>$$</option></term> |
63749b1a | 697 | <listitem> |
909f413d | 698 | <para>The <literal>$</literal> character itself.</para> |
63749b1a KS |
699 | </listitem> |
700 | </varlistentry> | |
701 | </variablelist> | |
63749b1a KS |
702 | </refsect1> |
703 | ||
63749b1a KS |
704 | <refsect1> |
705 | <title>See Also</title> | |
706 | <para><citerefentry> | |
b79f817b | 707 | <refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum> |
ad29a9f1 | 708 | </citerefentry>, |
63749b1a KS |
709 | <citerefentry> |
710 | <refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum> | |
711 | </citerefentry></para> | |
712 | </refsect1> | |
713 | </refentry> |