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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> | |
eb75d0ed | 33 | <refpurpose>Dynamic device management</refpurpose> |
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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 | ||
eb75d0ed | 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 |
e0e009c0 | 66 | over files with the same name in <filename>/usr/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 | |
e0e009c0 | 69 | <filename>/usr/lib</filename>, pointing to <filename>/dev/null</filename>, |
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70 | disables the rules file entirely. Rule files must have the extension |
71 | <filename>.rules</filename>; other extensions are ignored.</para> | |
63749b1a | 72 | |
feedf8f3 | 73 | <para>Every line in the rules file contains at least one key-value pair. |
909f413d | 74 | Except for empty lines or lines beginning with <literal>#</literal>, which are ignored. |
bb31a4ac | 75 | There are two kinds of keys: match and assignment. |
6ec0ac43 TG |
76 | If all match keys match against their values, the rule gets applied and the |
77 | assignment keys get the specified values assigned.</para> | |
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78 | |
79 | <para>A matching rule may rename a network interface, add symlinks | |
80 | pointing to the device node, or run a specified program as part of | |
81 | the event handling.</para> | |
82 | ||
55f5037c MW |
83 | <para>A rule consists of a comma-separated list of one or more key-value pairs. |
84 | Each key has a distinct operation, depending on the used operator. Valid | |
63749b1a KS |
85 | operators are:</para> |
86 | <variablelist> | |
87 | <varlistentry> | |
6b76fa66 | 88 | <term><literal>==</literal></term> |
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89 | <listitem> |
90 | <para>Compare for equality.</para> | |
91 | </listitem> | |
92 | </varlistentry> | |
93 | ||
94 | <varlistentry> | |
6b76fa66 | 95 | <term><literal>!=</literal></term> |
63749b1a KS |
96 | <listitem> |
97 | <para>Compare for inequality.</para> | |
98 | </listitem> | |
99 | </varlistentry> | |
100 | ||
101 | <varlistentry> | |
6b76fa66 | 102 | <term><literal>=</literal></term> |
63749b1a | 103 | <listitem> |
0e846301 | 104 | <para>Assign a value to a key. Keys that represent a list are reset |
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105 | and only this single value is assigned.</para> |
106 | </listitem> | |
107 | </varlistentry> | |
108 | ||
109 | <varlistentry> | |
6b76fa66 | 110 | <term><literal>+=</literal></term> |
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111 | <listitem> |
112 | <para>Add the value to a key that holds a list of entries.</para> | |
113 | </listitem> | |
114 | </varlistentry> | |
115 | ||
116 | <varlistentry> | |
6b76fa66 | 117 | <term><literal>:=</literal></term> |
63749b1a | 118 | <listitem> |
2bf11540 | 119 | <para>Assign a value to a key finally; disallow any later changes.</para> |
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120 | </listitem> |
121 | </varlistentry> | |
122 | </variablelist> | |
123 | ||
124 | <para>The following key names can be used to match against device properties. | |
125 | Some of the keys also match against properties of the parent devices in sysfs, | |
126 | not only the device that has generated the event. If multiple keys that match | |
127 | a parent device are specified in a single rule, all these keys must match at | |
128 | one and the same parent device.</para> | |
ccc9a4f9 | 129 | <variablelist class='udev-directives'> |
63749b1a | 130 | <varlistentry> |
909f413d | 131 | <term><varname>ACTION</varname></term> |
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132 | <listitem> |
133 | <para>Match the name of the event action.</para> | |
134 | </listitem> | |
135 | </varlistentry> | |
136 | ||
137 | <varlistentry> | |
909f413d | 138 | <term><varname>DEVPATH</varname></term> |
63749b1a KS |
139 | <listitem> |
140 | <para>Match the devpath of the event device.</para> | |
141 | </listitem> | |
142 | </varlistentry> | |
143 | ||
144 | <varlistentry> | |
909f413d | 145 | <term><varname>KERNEL</varname></term> |
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146 | <listitem> |
147 | <para>Match the name of the event device.</para> | |
148 | </listitem> | |
149 | </varlistentry> | |
150 | ||
151 | <varlistentry> | |
909f413d | 152 | <term><varname>NAME</varname></term> |
63749b1a | 153 | <listitem> |
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154 | <para>Match the name of a network interface. It can be used once the |
155 | NAME key has been set in one of the preceding rules.</para> | |
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156 | </listitem> |
157 | </varlistentry> | |
158 | ||
159 | <varlistentry> | |
909f413d | 160 | <term><varname>SYMLINK</varname></term> |
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161 | <listitem> |
162 | <para>Match the name of a symlink targeting the node. It can | |
163 | be used once a SYMLINK key has been set in one of the preceding | |
164 | rules. There may be multiple symlinks; only one needs to match. | |
165 | </para> | |
166 | </listitem> | |
167 | </varlistentry> | |
168 | ||
169 | <varlistentry> | |
909f413d | 170 | <term><varname>SUBSYSTEM</varname></term> |
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171 | <listitem> |
172 | <para>Match the subsystem of the event device.</para> | |
173 | </listitem> | |
174 | </varlistentry> | |
175 | <varlistentry> | |
909f413d | 176 | <term><varname>DRIVER</varname></term> |
63749b1a | 177 | <listitem> |
2e7f69eb | 178 | <para>Match the driver name of the event device. Only set this key for devices |
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179 | which are bound to a driver at the time the event is generated.</para> |
180 | </listitem> | |
181 | </varlistentry> | |
182 | <varlistentry> | |
909f413d | 183 | <term><varname>ATTR{<replaceable>filename</replaceable>}</varname></term> |
63749b1a KS |
184 | <listitem> |
185 | <para>Match sysfs attribute values of the event device. Trailing | |
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186 | whitespace in the attribute values is ignored unless the specified match |
187 | value itself contains trailing whitespace. | |
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188 | </para> |
189 | </listitem> | |
190 | </varlistentry> | |
191 | ||
192 | <varlistentry> | |
909f413d | 193 | <term><varname>KERNELS</varname></term> |
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194 | <listitem> |
195 | <para>Search the devpath upwards for a matching device name.</para> | |
196 | </listitem> | |
197 | </varlistentry> | |
198 | ||
199 | <varlistentry> | |
909f413d | 200 | <term><varname>SUBSYSTEMS</varname></term> |
63749b1a KS |
201 | <listitem> |
202 | <para>Search the devpath upwards for a matching device subsystem name.</para> | |
203 | </listitem> | |
204 | </varlistentry> | |
205 | ||
206 | <varlistentry> | |
909f413d | 207 | <term><varname>DRIVERS</varname></term> |
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208 | <listitem> |
209 | <para>Search the devpath upwards for a matching device driver name.</para> | |
210 | </listitem> | |
211 | </varlistentry> | |
212 | ||
213 | <varlistentry> | |
909f413d | 214 | <term><varname>ATTRS{<replaceable>filename</replaceable>}</varname></term> |
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215 | <listitem> |
216 | <para>Search the devpath upwards for a device with matching sysfs attribute values. | |
909f413d | 217 | If multiple <varname>ATTRS</varname> matches are specified, all of them |
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218 | must match on the same device. Trailing whitespace in the attribute values is ignored |
219 | unless the specified match value itself contains trailing whitespace.</para> | |
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220 | </listitem> |
221 | </varlistentry> | |
222 | ||
7df0ed83 | 223 | <varlistentry> |
909f413d | 224 | <term><varname>TAGS</varname></term> |
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225 | <listitem> |
226 | <para>Search the devpath upwards for a device with matching tag.</para> | |
227 | </listitem> | |
228 | </varlistentry> | |
229 | ||
63749b1a | 230 | <varlistentry> |
909f413d | 231 | <term><varname>ENV{<replaceable>key</replaceable>}</varname></term> |
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232 | <listitem> |
233 | <para>Match against a device property value.</para> | |
234 | </listitem> | |
235 | </varlistentry> | |
236 | ||
237 | <varlistentry> | |
909f413d | 238 | <term><varname>TAG</varname></term> |
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239 | <listitem> |
240 | <para>Match against a device tag.</para> | |
241 | </listitem> | |
242 | </varlistentry> | |
243 | ||
244 | <varlistentry> | |
909f413d | 245 | <term><varname>TEST{<replaceable>octal mode mask</replaceable>}</varname></term> |
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246 | <listitem> |
247 | <para>Test the existence of a file. An octal mode mask can be specified | |
248 | if needed.</para> | |
249 | </listitem> | |
250 | </varlistentry> | |
251 | ||
252 | <varlistentry> | |
909f413d | 253 | <term><varname>PROGRAM</varname></term> |
63749b1a | 254 | <listitem> |
2e9820e3 MW |
255 | <para>Execute a program to determine whether there |
256 | is a match; the key is true if the program returns | |
63749b1a | 257 | successfully. The device properties are made available to the |
2e9820e3 MW |
258 | executed program in the environment. The program's stdout |
259 | is available in the RESULT key.</para> | |
b45f770f | 260 | <para>This can only be used for very short-running foreground tasks. For details |
909f413d | 261 | see <varname>RUN</varname>.</para> |
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262 | </listitem> |
263 | </varlistentry> | |
264 | ||
265 | <varlistentry> | |
909f413d | 266 | <term><varname>RESULT</varname></term> |
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267 | <listitem> |
268 | <para>Match the returned string of the last PROGRAM call. This key can | |
269 | be used in the same or in any later rule after a PROGRAM call.</para> | |
270 | </listitem> | |
271 | </varlistentry> | |
272 | </variablelist> | |
273 | ||
eb75d0ed | 274 | <para>Most of the fields support shell glob pattern matching. The following |
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275 | pattern characters are supported:</para> |
276 | <variablelist> | |
277 | <varlistentry> | |
6b76fa66 | 278 | <term><literal>*</literal></term> |
63749b1a | 279 | <listitem> |
954e9c52 | 280 | <para>Matches zero or more characters.</para> |
63749b1a KS |
281 | </listitem> |
282 | </varlistentry> | |
283 | <varlistentry> | |
6b76fa66 | 284 | <term><literal>?</literal></term> |
63749b1a KS |
285 | <listitem> |
286 | <para>Matches any single character.</para> | |
287 | </listitem> | |
288 | </varlistentry> | |
289 | <varlistentry> | |
6b76fa66 | 290 | <term><literal>[]</literal></term> |
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291 | <listitem> |
292 | <para>Matches any single character specified within the brackets. For | |
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293 | example, the pattern string <literal>tty[SR]</literal> |
294 | would match either <literal>ttyS</literal> or <literal>ttyR</literal>. | |
295 | Ranges are also supported via the <literal>-</literal> character. | |
2c47027b | 296 | For example, to match on the range of all digits, the pattern [0-9] could |
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297 | be used. If the first character following the <literal>[</literal> is a |
298 | <literal>!</literal>, any characters not enclosed are matched.</para> | |
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299 | </listitem> |
300 | </varlistentry> | |
301 | </variablelist> | |
302 | ||
303 | <para>The following keys can get values assigned:</para> | |
ccc9a4f9 | 304 | <variablelist class='udev-directives'> |
63749b1a | 305 | <varlistentry> |
909f413d | 306 | <term><varname>NAME</varname></term> |
63749b1a | 307 | <listitem> |
220893b3 | 308 | <para>The name to use for a network interface. The name of a device node |
bb31a4ac | 309 | cannot be changed by udev, only additional symlinks can be created.</para> |
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310 | </listitem> |
311 | </varlistentry> | |
312 | ||
313 | <varlistentry> | |
909f413d | 314 | <term><varname>SYMLINK</varname></term> |
63749b1a | 315 | <listitem> |
933b5623 | 316 | <para>The name of a symlink targeting the node. Every matching rule adds |
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317 | this value to the list of symlinks to be created.</para> |
318 | <para>The set of characters to name a symlink is limited. Allowed | |
909f413d ZJS |
319 | characters are <literal>0-9A-Za-z#+-.:=@_/</literal>, valid UTF-8 character |
320 | sequences, and <literal>\x00</literal> hex encoding. All other | |
321 | characters are replaced by a <literal>_</literal> character.</para> | |
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322 | <para>Multiple symlinks may be specified by separating the names by the |
323 | space character. In case multiple devices claim the same name, the link | |
324 | always points to the device with the highest link_priority. If the current | |
325 | device goes away, the links are re-evaluated and the device with the | |
326 | next highest link_priority becomes the owner of the link. If no | |
327 | link_priority is specified, the order of the devices (and which one of | |
328 | them owns the link) is undefined.</para> | |
329 | <para>Symlink names must never conflict with the kernel's default device | |
330 | node names, as that would result in unpredictable behavior. | |
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331 | </para> |
332 | </listitem> | |
333 | </varlistentry> | |
334 | ||
335 | <varlistentry> | |
909f413d | 336 | <term><varname>OWNER</varname>, <varname>GROUP</varname>, <varname>MODE</varname></term> |
63749b1a | 337 | <listitem> |
91418155 | 338 | <para>The permissions for the device node. Every specified value overrides |
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339 | the compiled-in default value.</para> |
340 | </listitem> | |
341 | </varlistentry> | |
342 | ||
c26547d6 KS |
343 | <varlistentry> |
344 | <term><varname>SECLABEL{<replaceable>module</replaceable>}</varname></term> | |
345 | <listitem> | |
346 | <para>Applies the specified Linux Security Module label to the device node.</para> | |
347 | </listitem> | |
348 | </varlistentry> | |
349 | ||
63749b1a | 350 | <varlistentry> |
909f413d | 351 | <term><varname>ATTR{<replaceable>key</replaceable>}</varname></term> |
63749b1a KS |
352 | <listitem> |
353 | <para>The value that should be written to a sysfs attribute of the | |
354 | event device.</para> | |
355 | </listitem> | |
356 | </varlistentry> | |
357 | ||
358 | <varlistentry> | |
909f413d | 359 | <term><varname>ENV{<replaceable>key</replaceable>}</varname></term> |
63749b1a | 360 | <listitem> |
909f413d | 361 | <para>Set a device property value. Property names with a leading <literal>.</literal> |
ed9c5fb7 MW |
362 | are neither stored in the database nor exported to events or |
363 | external tools (run by, say, the PROGRAM match key).</para> | |
63749b1a KS |
364 | </listitem> |
365 | </varlistentry> | |
366 | ||
367 | <varlistentry> | |
909f413d | 368 | <term><varname>TAG</varname></term> |
63749b1a KS |
369 | <listitem> |
370 | <para>Attach a tag to a device. This is used to filter events for users | |
371 | of libudev's monitor functionality, or to enumerate a group of tagged | |
372 | devices. The implementation can only work efficiently if only a few | |
373 | tags are attached to a device. It is only meant to be used in | |
374 | contexts with specific device filter requirements, and not as a | |
375 | general-purpose flag. Excessive use might result in inefficient event | |
376 | handling.</para> | |
377 | </listitem> | |
378 | </varlistentry> | |
379 | ||
380 | <varlistentry> | |
909f413d | 381 | <term><varname>RUN{<replaceable>type</replaceable>}</varname></term> |
63749b1a | 382 | <listitem> |
08cbc57e TG |
383 | <para>Add a program to the list of programs to be executed after processing all the |
384 | rules for a specific event, depending on <literal>type</literal>:</para> | |
72c6cf8f TG |
385 | <variablelist> |
386 | <varlistentry> | |
387 | <term><literal>program</literal></term> | |
388 | <listitem> | |
389 | <para>Execute an external program specified as the assigned | |
390 | value. If no absolute path is given, the program is expected to live in | |
391 | /usr/lib/udev, otherwise the absolute path must be specified.</para> | |
392 | <para>This is the default if no <replaceable>type</replaceable> is | |
393 | specified.</para> | |
394 | </listitem> | |
395 | </varlistentry> | |
396 | <varlistentry> | |
397 | <term><literal>builtin</literal></term> | |
398 | <listitem> | |
909f413d | 399 | <para>As <varname>program</varname>, but use one of the built-in programs rather |
72c6cf8f TG |
400 | than an external one.</para> |
401 | </listitem> | |
402 | </varlistentry> | |
403 | </variablelist> | |
404 | <para>The program name and following arguments are separated by spaces. | |
405 | Single quotes can be used to specify arguments with spaces.</para> | |
b45f770f | 406 | <para>This can only be used for very short-running foreground tasks. Running an |
2b76eb68 | 407 | event process for a long period of time may block all further events for |
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408 | this or a dependent device.</para> |
409 | <para>Starting daemons or other long running processes is not appropriate | |
410 | for udev; the forked processes, detached or not, will be unconditionally | |
411 | killed after the event handling has finished.</para> | |
63749b1a KS |
412 | </listitem> |
413 | </varlistentry> | |
414 | ||
415 | <varlistentry> | |
909f413d | 416 | <term><varname>LABEL</varname></term> |
63749b1a | 417 | <listitem> |
c24dfc80 | 418 | <para>A named label to which a GOTO may jump.</para> |
63749b1a KS |
419 | </listitem> |
420 | </varlistentry> | |
421 | ||
422 | <varlistentry> | |
909f413d | 423 | <term><varname>GOTO</varname></term> |
63749b1a | 424 | <listitem> |
2f16de29 | 425 | <para>Jumps to the next LABEL with a matching name.</para> |
63749b1a KS |
426 | </listitem> |
427 | </varlistentry> | |
428 | ||
429 | <varlistentry> | |
909f413d | 430 | <term><varname>IMPORT{<replaceable>type</replaceable>}</varname></term> |
63749b1a KS |
431 | <listitem> |
432 | <para>Import a set of variables as device properties, | |
6b76fa66 | 433 | depending on <literal>type</literal>:</para> |
63749b1a KS |
434 | <variablelist> |
435 | <varlistentry> | |
6b76fa66 | 436 | <term><literal>program</literal></term> |
63749b1a KS |
437 | <listitem> |
438 | <para>Execute an external program specified as the assigned value and | |
439 | import its output, which must be in environment key | |
440 | format. Path specification, command/argument separation, | |
909f413d | 441 | and quoting work like in <varname>RUN</varname>.</para> |
63749b1a KS |
442 | </listitem> |
443 | </varlistentry> | |
444 | <varlistentry> | |
72c6cf8f TG |
445 | <term><literal>builtin</literal></term> |
446 | <listitem> | |
909f413d ZJS |
447 | <para>Similar to <literal>program</literal>, but use one of the |
448 | built-in programs rather than an external one.</para> | |
72c6cf8f TG |
449 | </listitem> |
450 | </varlistentry> | |
451 | <varlistentry> | |
6b76fa66 | 452 | <term><literal>file</literal></term> |
63749b1a | 453 | <listitem> |
b6a49cd6 MW |
454 | <para>Import a text file specified as the assigned value, the content |
455 | of which must be in environment key format.</para> | |
63749b1a KS |
456 | </listitem> |
457 | </varlistentry> | |
458 | <varlistentry> | |
6b76fa66 | 459 | <term><literal>db</literal></term> |
63749b1a KS |
460 | <listitem> |
461 | <para>Import a single property specified as the assigned value from the | |
462 | current device database. This works only if the database is already populated | |
463 | by an earlier event.</para> | |
464 | </listitem> | |
465 | </varlistentry> | |
c4f6dcc4 | 466 | <varlistentry> |
6b76fa66 | 467 | <term><literal>cmdline</literal></term> |
c4f6dcc4 | 468 | <listitem> |
ad9c70a8 | 469 | <para>Import a single property from the kernel command line. For simple flags |
909f413d | 470 | the value of the property is set to <literal>1</literal>.</para> |
c4f6dcc4 KS |
471 | </listitem> |
472 | </varlistentry> | |
63749b1a | 473 | <varlistentry> |
6b76fa66 | 474 | <term><literal>parent</literal></term> |
63749b1a KS |
475 | <listitem> |
476 | <para>Import the stored keys from the parent device by reading | |
477 | the database entry of the parent device. The value assigned to | |
478 | <option>IMPORT{parent}</option> is used as a filter of key names | |
eb75d0ed | 479 | to import (with the same shell glob pattern matching used for |
63749b1a KS |
480 | comparisons).</para> |
481 | </listitem> | |
482 | </varlistentry> | |
483 | </variablelist> | |
b45f770f KS |
484 | <para>This can only be used for very short-running foreground tasks. For details |
485 | see <option>RUN</option>.</para> | |
63749b1a KS |
486 | </listitem> |
487 | </varlistentry> | |
488 | ||
489 | <varlistentry> | |
909f413d | 490 | <term><varname>WAIT_FOR</varname></term> |
63749b1a | 491 | <listitem> |
793681cb MW |
492 | <para>Wait for a file to become available or until a timeout of |
493 | 10 seconds expires. The path is relative to the sysfs device; | |
494 | if no path is specified, this waits for an attribute to appear.</para> | |
63749b1a KS |
495 | </listitem> |
496 | </varlistentry> | |
497 | ||
498 | <varlistentry> | |
909f413d | 499 | <term><varname>OPTIONS</varname></term> |
63749b1a KS |
500 | <listitem> |
501 | <para>Rule and device options:</para> | |
ccc9a4f9 | 502 | <variablelist class='udev-directives'> |
63749b1a KS |
503 | <varlistentry> |
504 | <term><option>link_priority=<replaceable>value</replaceable></option></term> | |
505 | <listitem> | |
506 | <para>Specify the priority of the created symlinks. Devices with higher | |
507 | priorities overwrite existing symlinks of other devices. The default is 0.</para> | |
508 | </listitem> | |
509 | </varlistentry> | |
510 | <varlistentry> | |
511 | <term><option>event_timeout=</option></term> | |
512 | <listitem> | |
933b5623 MW |
513 | <para>Number of seconds an event waits for operations to finish before |
514 | giving up and terminating itself.</para> | |
63749b1a KS |
515 | </listitem> |
516 | </varlistentry> | |
517 | <varlistentry> | |
518 | <term><option>string_escape=<replaceable>none|replace</replaceable></option></term> | |
519 | <listitem> | |
520 | <para>Usually control and other possibly unsafe characters are replaced | |
521 | in strings used for device naming. The mode of replacement can be specified | |
522 | with this option.</para> | |
523 | </listitem> | |
524 | </varlistentry> | |
9fa68615 KS |
525 | <varlistentry> |
526 | <term><option>static_node=</option></term> | |
527 | <listitem> | |
0fbda083 | 528 | <para>Apply the permissions specified in this rule to the static device node with |
84b6ad70 TG |
529 | the specified name. Also, for every tag specified in this rule, create a symlink |
530 | in the directory | |
531 | <filename>/run/udev/static_node-tags/<replaceable>tag</replaceable></filename> | |
532 | pointing at the static device node with the specified name. Static device node | |
533 | creation is performed by systemd-tmpfiles before systemd-udevd is started. The | |
534 | static nodes might not have a corresponding kernel device; they are used to | |
535 | trigger automatic kernel module loading when they are accessed.</para> | |
9fa68615 KS |
536 | </listitem> |
537 | </varlistentry> | |
63749b1a KS |
538 | <varlistentry> |
539 | <term><option>watch</option></term> | |
540 | <listitem> | |
620da34d MW |
541 | <para>Watch the device node with inotify; when the node is closed after being opened for |
542 | writing, a change uevent is synthesized.</para> | |
63749b1a KS |
543 | </listitem> |
544 | </varlistentry> | |
3b529da4 KS |
545 | <varlistentry> |
546 | <term><option>nowatch</option></term> | |
547 | <listitem> | |
548 | <para>Disable the watching of a device node with inotify.</para> | |
549 | </listitem> | |
550 | </varlistentry> | |
63749b1a KS |
551 | </variablelist> |
552 | </listitem> | |
553 | </varlistentry> | |
554 | </variablelist> | |
555 | ||
909f413d ZJS |
556 | <para>The <varname>NAME</varname>, <varname>SYMLINK</varname>, <varname>PROGRAM</varname>, |
557 | <varname>OWNER</varname>, <varname>GROUP</varname>, <varname>MODE</varname> and <varname>RUN</varname> | |
558 | fields support simple string substitutions. The <varname>RUN</varname> | |
57e80484 MW |
559 | substitutions are performed after all rules have been processed, right before the program |
560 | is executed, allowing for the use of device properties set by earlier matching | |
561 | rules. For all other fields, substitutions are performed while the individual rule is | |
63749b1a | 562 | being processed. The available substitutions are:</para> |
ccc9a4f9 | 563 | <variablelist class='udev-directives'> |
63749b1a KS |
564 | <varlistentry> |
565 | <term><option>$kernel</option>, <option>%k</option></term> | |
566 | <listitem> | |
567 | <para>The kernel name for this device.</para> | |
568 | </listitem> | |
569 | </varlistentry> | |
570 | ||
571 | <varlistentry> | |
572 | <term><option>$number</option>, <option>%n</option></term> | |
573 | <listitem> | |
909f413d ZJS |
574 | <para>The kernel number for this device. For example, |
575 | <literal>sda3</literal> has kernel number <literal>3</literal>.</para> | |
63749b1a KS |
576 | </listitem> |
577 | </varlistentry> | |
578 | ||
579 | <varlistentry> | |
580 | <term><option>$devpath</option>, <option>%p</option></term> | |
581 | <listitem> | |
582 | <para>The devpath of the device.</para> | |
583 | </listitem> | |
584 | </varlistentry> | |
585 | ||
586 | <varlistentry> | |
587 | <term><option>$id</option>, <option>%b</option></term> | |
588 | <listitem> | |
589 | <para>The name of the device matched while searching the devpath upwards for | |
590 | <option>SUBSYSTEMS</option>, <option>KERNELS</option>, <option>DRIVERS</option> and <option>ATTRS</option>. | |
591 | </para> | |
592 | </listitem> | |
593 | </varlistentry> | |
594 | ||
595 | <varlistentry> | |
596 | <term><option>$driver</option></term> | |
597 | <listitem> | |
598 | <para>The driver name of the device matched while searching the devpath upwards for | |
599 | <option>SUBSYSTEMS</option>, <option>KERNELS</option>, <option>DRIVERS</option> and <option>ATTRS</option>. | |
600 | </para> | |
601 | </listitem> | |
602 | </varlistentry> | |
603 | ||
604 | <varlistentry> | |
605 | <term><option>$attr{<replaceable>file</replaceable>}</option>, <option>%s{<replaceable>file</replaceable>}</option></term> | |
606 | <listitem> | |
0e846301 | 607 | <para>The value of a sysfs attribute found at the device where |
63749b1a | 608 | all keys of the rule have matched. If the matching device does not have |
83184d00 | 609 | such an attribute, and a previous KERNELS, SUBSYSTEMS, DRIVERS, or |
f2db23cd | 610 | ATTRS test selected a parent device, then the attribute from that |
f61501b0 MW |
611 | parent device is used.</para> |
612 | <para>If the attribute is a symlink, the last element of the symlink target is | |
63749b1a KS |
613 | returned as the value.</para> |
614 | </listitem> | |
615 | </varlistentry> | |
616 | ||
617 | <varlistentry> | |
618 | <term><option>$env{<replaceable>key</replaceable>}</option>, <option>%E{<replaceable>key</replaceable>}</option></term> | |
619 | <listitem> | |
620 | <para>A device property value.</para> | |
621 | </listitem> | |
622 | </varlistentry> | |
623 | ||
624 | <varlistentry> | |
625 | <term><option>$major</option>, <option>%M</option></term> | |
626 | <listitem> | |
627 | <para>The kernel major number for the device.</para> | |
628 | </listitem> | |
629 | </varlistentry> | |
630 | ||
631 | <varlistentry> | |
632 | <term><option>$minor</option>, <option>%m</option></term> | |
633 | <listitem> | |
634 | <para>The kernel minor number for the device.</para> | |
635 | </listitem> | |
636 | </varlistentry> | |
637 | ||
638 | <varlistentry> | |
639 | <term><option>$result</option>, <option>%c</option></term> | |
640 | <listitem> | |
641 | <para>The string returned by the external program requested with PROGRAM. | |
21188522 | 642 | A single part of the string, separated by a space character, may be selected |
909f413d ZJS |
643 | by specifying the part number as an attribute: <literal>%c{N}</literal>. |
644 | If the number is followed by the <literal>+</literal> character, this part plus all remaining parts | |
645 | of the result string are substituted: <literal>%c{N+}</literal>.</para> | |
63749b1a KS |
646 | </listitem> |
647 | </varlistentry> | |
648 | ||
649 | <varlistentry> | |
650 | <term><option>$parent</option>, <option>%P</option></term> | |
651 | <listitem> | |
652 | <para>The node name of the parent device.</para> | |
653 | </listitem> | |
654 | </varlistentry> | |
655 | ||
656 | <varlistentry> | |
657 | <term><option>$name</option></term> | |
658 | <listitem> | |
220893b3 | 659 | <para>The current name of the device. If not changed by a rule, it is the |
63749b1a KS |
660 | name of the kernel device.</para> |
661 | </listitem> | |
662 | </varlistentry> | |
663 | ||
664 | <varlistentry> | |
665 | <term><option>$links</option></term> | |
666 | <listitem> | |
e8b5e4e5 | 667 | <para>A space-separated list of the current symlinks. The value is |
2d74bc75 | 668 | only set during a remove event or if an earlier rule assigned a value.</para> |
63749b1a KS |
669 | </listitem> |
670 | </varlistentry> | |
671 | ||
672 | <varlistentry> | |
673 | <term><option>$root</option>, <option>%r</option></term> | |
674 | <listitem> | |
675 | <para>The udev_root value.</para> | |
676 | </listitem> | |
677 | </varlistentry> | |
678 | ||
679 | <varlistentry> | |
680 | <term><option>$sys</option>, <option>%S</option></term> | |
681 | <listitem> | |
682 | <para>The sysfs mount point.</para> | |
683 | </listitem> | |
684 | </varlistentry> | |
685 | ||
686 | <varlistentry> | |
220893b3 | 687 | <term><option>$devnode</option>, <option>%N</option></term> |
63749b1a | 688 | <listitem> |
220893b3 | 689 | <para>The name of the device node.</para> |
63749b1a KS |
690 | </listitem> |
691 | </varlistentry> | |
692 | ||
693 | <varlistentry> | |
909f413d | 694 | <term><option>%%</option></term> |
63749b1a | 695 | <listitem> |
909f413d | 696 | <para>The <literal>%</literal> character itself.</para> |
63749b1a KS |
697 | </listitem> |
698 | </varlistentry> | |
699 | ||
700 | <varlistentry> | |
909f413d | 701 | <term><option>$$</option></term> |
63749b1a | 702 | <listitem> |
909f413d | 703 | <para>The <literal>$</literal> character itself.</para> |
63749b1a KS |
704 | </listitem> |
705 | </varlistentry> | |
706 | </variablelist> | |
63749b1a KS |
707 | </refsect1> |
708 | ||
eb75d0ed KS |
709 | <refsect1><title>Hardware Database Files</title> |
710 | <para>The hwdb files are read from the files located in the | |
711 | system hwdb directory <filename>/usr/lib/udev/hwdb.d</filename>, | |
712 | the volatile runtime directory <filename>/run/udev/hwdb.d</filename> | |
713 | and the local administration directory <filename>/etc/udev/hwdb.d</filename>. | |
0778c3db | 714 | All hwdb files are collectively sorted and processed in lexical order, |
eb75d0ed KS |
715 | regardless of the directories in which they live. However, files with |
716 | identical filenames replace each other. Files in <filename>/etc</filename> | |
717 | have the highest priority, files in <filename>/run</filename> take precedence | |
e0e009c0 | 718 | over files with the same name in <filename>/usr/lib</filename>. This can be |
eb75d0ed | 719 | used to override a system-supplied hwdb file with a local file if needed; |
0778c3db | 720 | a symlink in <filename>/etc</filename> with the same name as a hwdb file in |
e0e009c0 | 721 | <filename>/usr/lib</filename>, pointing to <filename>/dev/null</filename>, |
0778c3db | 722 | disables the hwdb file entirely. hwdb files must have the extension |
eb75d0ed KS |
723 | <filename>.hwdb</filename>; other extensions are ignored.</para> |
724 | ||
725 | <para>The hwdb file contains data records consisting of matches and | |
726 | associated key-value pairs. Every record in the hwdb starts with one or | |
727 | more match string, specifying a shell glob to compare the database | |
728 | lookup string against. Multiple match lines are specified in additional | |
729 | consecutive lines. Every match line is compared indivdually, they are | |
730 | combined by OR. Every match line must start at the first character of | |
731 | the line.</para> | |
732 | ||
733 | <para>The match lines are followed by one or more key-value pair lines, which | |
734 | are recognized by a leading space character. The key name and value are separated | |
735 | by <literal>=</literal>. An empty line signifies the end | |
736 | of a record. Lines beginning with <literal>#</literal> are ignored.</para> | |
737 | ||
738 | <para>The content of all hwdb files is read by | |
739 | <citerefentry><refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
740 | and compiled to a binary database located at <filename>/etc/udev/hwdb.bin</filename>. | |
741 | During runtime only the binary database is used.</para> | |
742 | </refsect1> | |
743 | ||
1f06807c | 744 | <refsect1><title>Network Link Configuration</title> |
22925e1a | 745 | <para>Network link configuration is performed by the <literal>net_setup_link</literal> |
1f06807c TG |
746 | udev builtin.</para> |
747 | ||
748 | <para>The link files are read from the files located in the | |
749 | system network directory <filename>/usr/lib/systemd/network</filename>, | |
750 | the volatile runtime network directory <filename>/run/systemd/network</filename> | |
751 | and the local administration network directory <filename>/etc/systemd/network</filename>. | |
22925e1a | 752 | Link files must have the extension <filename>.link</filename>; other extensions are ignored. |
1f06807c TG |
753 | All link files are collectively sorted and processed in lexical order, |
754 | regardless of the directories in which they live. However, files with | |
755 | identical filenames replace each other. Files in <filename>/etc</filename> | |
756 | have the highest priority, files in <filename>/run</filename> take precedence | |
e0e009c0 | 757 | over files with the same name in <filename>/usr/lib</filename>. This can be |
1f06807c TG |
758 | used to override a system-supplied link file with a local file if needed; |
759 | a symlink in <filename>/etc</filename> with the same name as a link file in | |
e0e009c0 | 760 | <filename>/usr/lib</filename>, pointing to <filename>/dev/null</filename>, |
2b51bd3c | 761 | disables the link file entirely.</para> |
1f06807c TG |
762 | |
763 | <para>The link file contains a <literal>[Match]</literal> section, which | |
764 | determines if a given link file may be applied to a given device; and a | |
765 | <literal>[Link]</literal> section specifying how the device should be | |
766 | configured. The first (in lexical order) of the link files that matches | |
767 | a given device is applied.</para> | |
768 | ||
769 | <para>A link file is said to match a device if each of the entries in the | |
770 | <literal>[Match]</literal> section matches, or if the section is empty. | |
771 | The following keys are accepted:</para> | |
772 | ||
773 | <variablelist class='network-directives'> | |
774 | <varlistentry> | |
775 | <term><varname>MACAddress</varname></term> | |
776 | <listitem> | |
777 | <para>The hardware address. | |
778 | </para> | |
779 | </listitem> | |
780 | </varlistentry> | |
781 | <varlistentry> | |
782 | <term><varname>Path</varname></term> | |
783 | <listitem> | |
784 | <para>The persistent path, as exposed by the udev property <literal>ID_PATH</literal>.</para> | |
785 | </listitem> | |
786 | </varlistentry> | |
787 | <varlistentry> | |
788 | <term><varname>Driver</varname></term> | |
789 | <listitem> | |
790 | <para>The driver currently bound to the device, as exposed by the udev property <literal>DRIVER</literal>.</para> | |
791 | </listitem> | |
792 | </varlistentry> | |
793 | <varlistentry> | |
794 | <term><varname>Type</varname></term> | |
795 | <listitem> | |
d69b12ac | 796 | <para>The device type, as exposed by the udev property <literal>DEVTYPE</literal>.</para> |
1f06807c TG |
797 | </listitem> |
798 | </varlistentry> | |
799 | </variablelist> | |
800 | ||
801 | <para>The <literal>[Link]</literal> section accepts the following keys:</para> | |
802 | ||
803 | <variablelist class='network-directives'> | |
804 | <varlistentry> | |
805 | <term><varname>Description</varname></term> | |
806 | <listitem> | |
d2df0d0e TG |
807 | <para>A description of the device.</para> |
808 | </listitem> | |
809 | </varlistentry> | |
810 | <varlistentry> | |
811 | <term><varname>Alias</varname></term> | |
812 | <listitem> | |
813 | <para>The <literal>ifalias</literal> is set to this value.</para> | |
1f06807c TG |
814 | </listitem> |
815 | </varlistentry> | |
816 | <varlistentry> | |
817 | <term><varname>MACAddressPolicy</varname></term> | |
818 | <listitem> | |
819 | <para>The policy by which the MAC address should be set. The available policies are:</para> | |
820 | <variablelist> | |
821 | <varlistentry> | |
822 | <term><literal>persistent</literal></term> | |
823 | <listitem> | |
824 | <para>If the hardware has a persistent MAC address, as most hardware should, and this is used by | |
825 | the kernel, nothing is done. Otherwise, a new MAC address is generated which is guaranteed to be | |
826 | the same on every boot for the given machine and the given device, but which is otherwise random. | |
827 | </para> | |
828 | </listitem> | |
829 | </varlistentry> | |
830 | <varlistentry> | |
831 | <term><literal>random</literal></term> | |
832 | <listitem> | |
833 | <para>If the kernel is using a random MAC address, nothing is done. Otherwise, a new address is | |
834 | randomly generated each time the device appears, typically at boot.</para> | |
835 | </listitem> | |
836 | </varlistentry> | |
837 | </variablelist> | |
838 | </listitem> | |
839 | </varlistentry> | |
840 | <varlistentry> | |
841 | <term><varname>MACAddress</varname></term> | |
842 | <listitem> | |
843 | <para>The MAC address to use, if no <literal>MACAddressPolicy</literal> is specified.</para> | |
844 | </listitem> | |
845 | </varlistentry> | |
846 | <varlistentry> | |
847 | <term><varname>NamePolicy</varname></term> | |
848 | <listitem> | |
849 | <para>An ordered, space-separated list of policies by which the interface name should be set. | |
850 | <literal>NamePolicy</literal> may be disabeld by specifying <literal>net.ifnames=0</literal> on the | |
851 | kernel commandline. Each of the policies may fail, and the first successfull one is used. The name | |
852 | is not set directly, but exported to udev as the property <literal>ID_NET_NAME</literal>, which is | |
853 | by default used by an udev rule to set <literal>NAME</literal>. The available policies are:</para> | |
854 | <variablelist> | |
855 | <varlistentry> | |
856 | <term><literal>onboard</literal></term> | |
857 | <listitem> | |
858 | <para>The name is set based on information given by the firmware for on-board devices, as | |
859 | exported by the udev property <literal>ID_NET_NAME_ONBOARD</literal>.</para> | |
860 | </listitem> | |
861 | </varlistentry> | |
862 | <varlistentry> | |
863 | <term><literal>slot</literal></term> | |
864 | <listitem> | |
865 | <para>The name is set based on information given by the firmware for hot-plug devices, as | |
866 | exported by the udev property <literal>ID_NET_NAME_SLOT</literal>.</para> | |
867 | </listitem> | |
868 | </varlistentry> | |
869 | <varlistentry> | |
870 | <term><literal>path</literal></term> | |
871 | <listitem> | |
872 | <para>The name is set based on the device's physical location, as exported by the udev | |
873 | property <literal>ID_NET_NAME_PATH</literal>.</para> | |
874 | </listitem> | |
875 | </varlistentry> | |
876 | <varlistentry> | |
877 | <term><literal>mac</literal></term> | |
878 | <listitem> | |
879 | <para>The name is set based on the device's persistent MAC address, as exported by the udev | |
880 | property <literal>ID_NET_NAME_MAC</literal>.</para> | |
881 | </listitem> | |
882 | </varlistentry> | |
883 | </variablelist> | |
884 | </listitem> | |
885 | </varlistentry> | |
886 | <varlistentry> | |
887 | <term><varname>Name</varname></term> | |
888 | <listitem> | |
889 | <para>The interface name to use in case all the policies specified in <literal>NamePolicy</literal> | |
890 | fail, or in case <literal>NamePolicy</literal> is missing or disabled.</para> | |
891 | </listitem> | |
892 | </varlistentry> | |
893 | <varlistentry> | |
894 | <term><varname>MTU</varname></term> | |
895 | <listitem> | |
896 | <para>The MTU to set for the device.</para> | |
897 | </listitem> | |
898 | </varlistentry> | |
899 | <varlistentry> | |
900 | <term><varname>SpeedMBytes</varname></term> | |
901 | <listitem> | |
902 | <para>The speed to set for the device.</para> | |
903 | </listitem> | |
904 | </varlistentry> | |
905 | <varlistentry> | |
906 | <term><varname>Duplex</varname></term> | |
907 | <listitem> | |
908 | <para>The duplex mode to set for the device. The accepted values are <literal>half</literal> and | |
909 | <literal>full</literal>.</para> | |
910 | </listitem> | |
911 | </varlistentry> | |
912 | <varlistentry> | |
913 | <term><varname>WakeOnLan</varname></term> | |
914 | <listitem> | |
915 | <para>The Wake-On-Lan policy to set for the device. The supported values are:</para> | |
916 | <variablelist> | |
917 | <varlistentry> | |
918 | <term><literal>phy</literal></term> | |
919 | <listitem> | |
920 | <para>Wake on PHY activity.</para> | |
921 | </listitem> | |
922 | </varlistentry> | |
923 | <varlistentry> | |
924 | <term><literal>magic</literal></term> | |
925 | <listitem> | |
926 | <para>Wake on receipt of magic packet.</para> | |
927 | </listitem> | |
928 | </varlistentry> | |
929 | <varlistentry> | |
930 | <term><literal>off</literal></term> | |
931 | <listitem> | |
932 | <para>Never wake.</para> | |
933 | </listitem> | |
934 | </varlistentry> | |
935 | </variablelist> | |
936 | </listitem> | |
937 | </varlistentry> | |
938 | </variablelist> | |
939 | </refsect1> | |
940 | ||
63749b1a KS |
941 | <refsect1> |
942 | <title>See Also</title> | |
943 | <para><citerefentry> | |
b79f817b | 944 | <refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum> |
ad29a9f1 | 945 | </citerefentry>, |
63749b1a KS |
946 | <citerefentry> |
947 | <refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum> | |
948 | </citerefentry></para> | |
949 | </refsect1> | |
950 | </refentry> |