]>
Commit | Line | Data |
---|---|---|
d3db5e5e | 1 | .TH UDEV 8 "October 2003" "" "Linux Administrator's Manual" |
04db8c9e | 2 | .SH NAME |
d3db5e5e | 3 | udev \- Linux configurable dynamic device naming support |
04db8c9e | 4 | .SH SYNOPSIS |
eb13ff87 | 5 | .BI udev " hotplug-subsystem" |
bef370d6 KS |
6 | .P |
7 | The environment must provide the following variables: | |
8 | .TP | |
9 | .B ACTION | |
10 | .IR add " or " remove | |
11 | signifies the connection or disconnection of a device. | |
12 | .TP | |
13 | .B DEVPATH | |
14 | The sysfs devpath of the device without the mountpoint but a leading slash. | |
15 | .P | |
b86f56ff | 16 | Additional optional environment variables: |
bef370d6 KS |
17 | .TP |
18 | .B UDEV_CONFIG_FILE | |
19 | Overrides the default location of the | |
20 | .B udev | |
21 | config file. | |
22 | .TP | |
fc238cff KS |
23 | .B UDEV_NO_DEVD |
24 | The default behavior of | |
25 | .B udev | |
26 | is to execute programs in the | |
27 | .I /etc/dev.d/ | |
28 | directory after device handling. If set, | |
29 | .B udev | |
30 | will skip this step. | |
04db8c9e GKH |
31 | .SH "DESCRIPTION" |
32 | .B udev | |
fc238cff KS |
33 | provides a dynamic device directory containing only the files for actually |
34 | present devices. It creates or removes device node files usually located in | |
35 | the /dev directory, or it renames network interfaces. | |
36 | .br | |
37 | ||
eb13ff87 | 38 | .P |
d3db5e5e | 39 | As part of the |
40 | .B hotplug | |
41 | subsystem, | |
42 | .B udev | |
eb13ff87 | 43 | is executed if a kernel device is added or removed from the system. |
d3db5e5e | 44 | On device creation, |
45 | .B udev | |
eb13ff87 | 46 | reads the sysfs directory of the given device to collect device attributes |
d3db5e5e | 47 | like label, serial number or bus device number. |
b86f56ff | 48 | These attributes may be used as keys to determine a |
fc238cff | 49 | unique name for the device. |
da86c7f0 KS |
50 | .B udev |
51 | maintains a database for devices present on the system. | |
eb13ff87 | 52 | .br |
d3db5e5e | 53 | On device removal, |
54 | .B udev | |
4bd46ac7 | 55 | queries its database for the name of the device file to be deleted. |
eb13ff87 | 56 | .SH "CONFIGURATION" |
83fa40fc KS |
57 | All |
58 | .B udev | |
59 | configuration files consist of a set of lines of text. All empty | |
b86f56ff | 60 | lines and lines beginning with a '#' will be ignored. |
4865de44 GKH |
61 | .P |
62 | ||
da86c7f0 | 63 | .B udev |
4865de44 | 64 | expects its main configuration file at |
167a27e7 | 65 | .IR /etc/udev/udev.conf . |
b86f56ff KS |
66 | The file consists of a set of variables and values allowing the user to |
67 | override default udev values. The following variables can be overridden | |
68 | in this file: | |
4865de44 GKH |
69 | .TP |
70 | .B udev_root | |
b86f56ff KS |
71 | Indicates where to place the device nodes in the filesystem. The default |
72 | value is | |
aef6bb13 | 73 | .IR @udevdir@/ . |
4865de44 GKH |
74 | .TP |
75 | .B udev_db | |
b86f56ff | 76 | The name and location of the udev database. The default value is |
326e0876 | 77 | .IR @udevdir@/.udev.tdb . |
4865de44 GKH |
78 | .TP |
79 | .B udev_rules | |
a5327755 KS |
80 | The name of the udev rules file or directory to look for files with the suffix |
81 | .IR .rules . | |
82 | All rule files are read in lexical order. The default value is | |
aef6bb13 | 83 | .IR /etc/udev/rules.d/ . |
4865de44 GKH |
84 | .TP |
85 | .B udev_permissions | |
a5327755 KS |
86 | The name of the udev permission file or directory to look for files with the |
87 | suffix | |
88 | .IR .permissions . | |
89 | All permission files are read in lexical order. The default value is | |
aef6bb13 | 90 | .IR /etc/udev/permissions.d/ . |
4865de44 | 91 | .TP |
0c040e8d | 92 | .B udev_log |
a5327755 | 93 | The switch, if udev logs some information for every device handled. |
fc238cff | 94 | The default value is |
167a27e7 | 95 | .IR yes . |
0c040e8d | 96 | .TP |
4865de44 | 97 | .B default_mode |
a5327755 KS |
98 | The default mode for all nodes not explicitely matching in the permissions |
99 | file. The default value is | |
167a27e7 | 100 | .IR 0666 . |
765cbd97 KS |
101 | .TP |
102 | .B default_owner | |
a5327755 KS |
103 | The default owner for all nodes not explicitely matching in the permissions |
104 | file. The default value is | |
167a27e7 | 105 | .IR root . |
765cbd97 KS |
106 | .TP |
107 | .B default_group | |
a5327755 KS |
108 | The default group for all nodes not explicitely matching in the permissions |
109 | file. The default value is | |
167a27e7 | 110 | .IR root . |
d3db5e5e | 111 | .br |
4865de44 | 112 | .P |
c6c13c31 | 113 | .RI "A sample " udev.conf " might look like this: |
4865de44 GKH |
114 | .sp |
115 | .nf | |
b86f56ff | 116 | # udev_root - where to place the device nodes in the filesystem |
aef6bb13 | 117 | udev_root="/udev" |
4865de44 | 118 | |
b86f56ff | 119 | # udev_db - The name and location of the udev database |
aef6bb13 | 120 | udev_db="/udev/.udev.tdb" |
4865de44 | 121 | |
a5327755 KS |
122 | # udev_rules - The name of the udev rules file or directory to look |
123 | for files with the suffix .rules | |
124 | udev_rules="/etc/udev/rules.d/" | |
4865de44 | 125 | |
aef6bb13 KS |
126 | # udev_permissions - The name of the udev permission file or directory |
127 | to look for files with the suffix .permissions | |
4865de44 GKH |
128 | udev_permissions="/etc/udev/udev.permissions" |
129 | ||
0c040e8d GKH |
130 | # udev_log - set to "yes" if you want logging, else "no" |
131 | udev_log="yes" | |
132 | ||
b86f56ff KS |
133 | # default_mode - set the default mode for all nodes not |
134 | # explicitely matching in the permissions file | |
4865de44 | 135 | default_mode="0666" |
765cbd97 | 136 | |
b86f56ff KS |
137 | # default_owner - set the default owner for all nodes not |
138 | # explicitely matching in the permissions file | |
765cbd97 KS |
139 | default_owner="root" |
140 | ||
b86f56ff KS |
141 | # default_group - set the default group for all nodes not |
142 | # explicitely matching in the permissions file | |
765cbd97 | 143 | default_group="root" |
4865de44 GKH |
144 | .fi |
145 | .P | |
aef6bb13 KS |
146 | The rules for device naming, are read from the files located in the |
147 | .I /etc/udev/rules.d/ | |
148 | directory, or at the location specified by the | |
4865de44 | 149 | .I udev_rules |
d94df232 | 150 | value in the |
4865de44 GKH |
151 | .I /etc/udev/udev.conf |
152 | file. | |
aef6bb13 | 153 | .br |
4bd46ac7 | 154 | Every line in the rules file defines the mapping between device attributes |
fc238cff KS |
155 | and the device name. One or more keys are specified to match a rule with |
156 | the current device. If all keys are matching, the rule will be applied and | |
157 | the name is used to name the device file or the network interface. | |
c6c13c31 | 158 | .br |
4bd46ac7 | 159 | If no matching rule is found, the default kernel device name is used. |
3370fb21 | 160 | .P |
c5828665 | 161 | Every rule consists of a list of comma separated fields: |
eb13ff87 | 162 | .sp |
311e9ae6 | 163 | .IR "key " ,[ "key " ,...] " name " [, " symlink" ] |
eb13ff87 | 164 | .sp |
b86f56ff | 165 | where fields are: |
d3db5e5e | 166 | .TP |
e15b5ed5 | 167 | .B BUS |
4bd46ac7 KS |
168 | Match the bus type of the device. |
169 | (The sysfs device bus must be able to be determined by a "device" symlink.) | |
170 | .TP | |
171 | .B KERNEL | |
172 | Match the kernel device name. | |
173 | .TP | |
174 | .B ID | |
175 | Match the device number on the bus, like PCI bus id. | |
176 | .TP | |
177 | .B PLACE | |
178 | Match the topological position on bus, like physical port of USB device | |
179 | .TP | |
16378373 | 180 | .BI SYSFS{ filename } |
4bd46ac7 KS |
181 | Match sysfs device attribute like label, vendor, USB serial number, SCSI UUID |
182 | or file system label. Up to 5 different sysfs files can be checked, with | |
b86f56ff | 183 | all of the values being required to match the rule. |
d5f91372 KS |
184 | .br |
185 | Trailing whitespace characters in the sysfs attribute value are ignored, if | |
186 | the key doesn't have any trailing whitespace characters by itself. | |
4bd46ac7 KS |
187 | .TP |
188 | .B PROGRAM | |
189 | Call external program. This key is valid if the program returns successful. | |
dde05ccb | 190 | The environment variables of |
bef370d6 KS |
191 | .B udev |
192 | are also available for the program. | |
193 | .br | |
b86f56ff | 194 | The string returned by the program may be additionally matched with the |
4bd46ac7 KS |
195 | .B RESULT |
196 | key. | |
197 | .TP | |
198 | .B RESULT | |
199 | Match the returned string of the last | |
200 | .B PROGRAM | |
b86f56ff | 201 | call. This key may be used in any following rule after a |
4bd46ac7 KS |
202 | .B PROGRAM |
203 | call. | |
311e9ae6 | 204 | .TP |
16378373 | 205 | .B NAME |
fc238cff KS |
206 | The name of the node to be created, or the name, the network interface |
207 | should be renamed to. | |
311e9ae6 KS |
208 | .br |
209 | If given with the attribute | |
16378373 | 210 | .BR NAME{ all_partitions } |
311e9ae6 | 211 | it will create all 15 partitions of a blockdevice. |
16378373 | 212 | This may be useful for removable media devices. |
311e9ae6 KS |
213 | .TP |
214 | .B SYMLINK | |
215 | The name of a symlink targeting the node. Multiple symlinks may be | |
216 | specified by separating the names by the space character. | |
2bd07cf2 KS |
217 | .br |
218 | If both the name and the symlink fields are omitted or its | |
219 | values empty, the device will be ignored and no node will be created. | |
220 | .br | |
221 | If only the symlink field is given and the name field is omitted, | |
222 | the rule will not be applied immediatly, but the symlink field is added | |
223 | to the symlink list of the rule which will create the node. | |
224 | This makes it possible to specify additional symlinks in a possibly | |
225 | separate rules file, while the device nodes are maintained by the | |
226 | distribution provided rules file. | |
e41016d3 KS |
227 | .TP |
228 | .B OWNER, GROUP, MODE | |
229 | The permissions for this device. Every specified value overwrites the value | |
230 | given in the permissions file. | |
16378373 | 231 | .P |
c6c13c31 | 232 | .RB "The " NAME " ," SYMLINK " and " PROGRAM |
83fa40fc | 233 | fields support simple printf-like string substitution: |
4b710f03 KS |
234 | .TP |
235 | .B %n | |
c6c13c31 | 236 | The "kernel number" of the device. |
63ead27c | 237 | For example, 'sda3' has a "kernel number" of '3'. |
4b710f03 | 238 | .TP |
170ae44e GKH |
239 | .B %k |
240 | The "kernel name" for the device. | |
241 | .TP | |
4b710f03 | 242 | .B %M |
c6c13c31 | 243 | The kernel major number for the device. |
4b710f03 KS |
244 | .TP |
245 | .B %m | |
c6c13c31 | 246 | The kernel minor number for the device. |
4b710f03 KS |
247 | .TP |
248 | .B %b | |
c6c13c31 | 249 | The bus id for the device. |
67922099 GKH |
250 | .TP |
251 | .B %c | |
b86f56ff | 252 | The string returned from the execution of |
e68faf51 | 253 | .B PROGRAM |
e68faf51 KS |
254 | (This does not work within the |
255 | .B PROGRAM | |
256 | field for the obvious reason.) | |
ad63031e | 257 | .br |
b86f56ff | 258 | A single part of the string, separated by a space character |
c5828665 | 259 | may be selected by specifying the part number as an attribute: |
558f80ba KS |
260 | .BI %c{ N } |
261 | If the number is followed by the + char this part plus | |
262 | all remaining parts of the result string are substituted: | |
263 | .BI %c{ N+ } | |
ad63031e KS |
264 | .TP |
265 | .BI %s{ filename } | |
266 | The content of a sysfs attribute. | |
36043f84 | 267 | .TP |
0a8dd7f3 DZ |
268 | .B %e |
269 | If a device node already exists with the name, the smallest positive | |
270 | decimal integer N is substituted such that the resulting name doesn't | |
271 | match an existing device node. Otherwise nothing is substituted. This | |
272 | can be used to create compatibility symlinks and enumerate devices of | |
273 | the same type originating from different kernel subsystems. | |
274 | .TP | |
b6864b4b | 275 | .B %% |
63ead27c KS |
276 | The '%' character itself. |
277 | .P | |
278 | The count of charcters to insert may be limited by specifying | |
279 | the format length value. For example, '%3s{file}' will only insert | |
280 | the first three characters of the sysfs attribute. | |
4b710f03 | 281 | .P |
c6c13c31 | 282 | .RI "A sample " udev.rules " might look like this:" |
eb13ff87 | 283 | .sp |
d3db5e5e | 284 | .nf |
67922099 | 285 | # if /sbin/scsi_id returns "OEM 0815" device will be called disk1 |
4bd46ac7 | 286 | BUS="scsi", PROGRAM="/sbin/scsi_id", RESULT="OEM 0815", NAME="disk1" |
67922099 | 287 | |
d3db5e5e | 288 | # USB printer to be called lp_color |
16378373 | 289 | BUS="usb", SYSFS{serial}="W09090207101241330", NAME="lp_color" |
d3db5e5e | 290 | |
b86f56ff | 291 | # SCSI disk with a specific vendor and model number will be called boot |
16378373 | 292 | BUS="scsi", SYSFS{vendor}="IBM", SYSFS{model}="ST336", NAME="boot%n" |
aa9c2a1e | 293 | |
d3db5e5e | 294 | # sound card with PCI bus id 00:0b.0 to be called dsp |
4bd46ac7 | 295 | BUS="pci", ID="00:0b.0", NAME="dsp" |
d3db5e5e | 296 | |
297 | # USB mouse at third port of the second hub to be called mouse1 | |
4bd46ac7 | 298 | BUS="usb", PLACE="2.3", NAME="mouse1" |
d3db5e5e | 299 | |
26004fcc | 300 | # ttyUSB1 should always be called pda with two additional symlinks |
4bd46ac7 | 301 | KERNEL="ttyUSB1", NAME="pda", SYMLINK="palmtop handheld" |
3370fb21 | 302 | |
26004fcc | 303 | # multiple USB webcams with symlinks to be called webcam0, webcam1, ... |
16378373 | 304 | BUS="usb", SYSFS{model}="XV3", NAME="video%n", SYMLINK="webcam%n" |
0a8dd7f3 DZ |
305 | |
306 | # grouping of optical drives from multiple kernel subsystems | |
307 | KERNEL="sr*", NAME="%k", SYMLINK="cdrom%e" | |
308 | KERNEL="scd*", NAME="%k", SYMLINK="cdrom%e" | |
309 | KERNEL="pcd*", NAME="%k", SYMLINK="cdrom%e" | |
310 | KERNEL="hd[a-z]", PROGRAM="/bin/cat /proc/ide/%k/media", RESULT="cdrom", | |
311 | NAME="%k", SYMLINK="cdrom%e" | |
312 | ||
d3db5e5e | 313 | .fi |
eb13ff87 | 314 | .P |
aef6bb13 KS |
315 | The permissions and ownership of the created device file is read from |
316 | the files located in the | |
317 | .I /etc/udev/permissions.d/ | |
318 | directory, or at the location specified by the | |
4865de44 | 319 | .I udev_permission |
c6c13c31 | 320 | value in the |
4865de44 GKH |
321 | .I /etc/udev/udev.conf |
322 | file. | |
eb13ff87 | 323 | .br |
5b8ba50a | 324 | Every line lists a device name followed by owner, group and permission |
07d7cfd1 | 325 | mode. All values are separated by colons. The name field may contain a |
83fa40fc | 326 | pattern to apply the values to a whole class of devices. |
eb13ff87 | 327 | .sp |
c6c13c31 | 328 | .RI "A sample " udev.permissions " might look like this:" |
eb13ff87 KS |
329 | .sp |
330 | .nf | |
331 | #name:user:group:mode | |
5b8ba50a | 332 | input/*:root:root:644 |
d0a4a110 | 333 | ttyUSB1:0:8:0660 |
5b8ba50a | 334 | video*:root:video:0660 |
eb13ff87 KS |
335 | dsp1:::0666 |
336 | .fi | |
07d7cfd1 | 337 | .P |
a6f01502 | 338 | The value |
339 | .I $local | |
b86f56ff | 340 | can be used instead of a specific username. In that case, udev will determine |
a6f01502 | 341 | the current local user at the time of device node creation and substitute |
342 | that username as the owner of the new device node. This is useful, for | |
343 | example, to let hot-plugged devices, such as cameras, be owned by the user at | |
344 | the current console. Note that if no user is currently logged in, or if udev | |
345 | otherwise fails to determine a current user, the | |
346 | .I default_owner | |
347 | value is used in lieu. | |
348 | .P | |
07d7cfd1 | 349 | A number of different fields in the above configuration files support a simple |
83fa40fc | 350 | form of shell style pattern matching. It supports the following pattern characters: |
07d7cfd1 GKH |
351 | .TP |
352 | .B * | |
353 | Matches zero, one, or more characters. | |
354 | .TP | |
355 | .B ? | |
356 | Matches any single character, but does not match zero characters. | |
357 | .TP | |
358 | .B [ ] | |
359 | Matches any single character specified within the brackets. For example, the | |
360 | pattern string "tty[SR]" would match either "ttyS" or "ttyR". Ranges are also | |
758f236f MI |
361 | supported within this match with the '\-' character. For example, to match on |
362 | the range of all digits, the pattern [0\-9] would be used. If the first character | |
b86f56ff | 363 | following the '[' is a '!', any character not enclosed is matched. |
fc238cff KS |
364 | .P |
365 | After device node creation, removal, or network device renaming, | |
366 | .B udev | |
367 | executes the programs in the directory tree under | |
368 | .IR /etc/dev.d/ . | |
369 | The name of a program must end with | |
370 | .I .dev | |
371 | suffix, to be recognized. | |
372 | .br | |
373 | In addition to the hotplug environment variables, | |
374 | .B DEVNAME | |
375 | is exported to make the name of the created node, or the name the network | |
376 | device is renamed to, available to the executed program. The programs in every | |
377 | directory are sorted in lexical order, while the directories are searched in | |
378 | the following order: | |
379 | .sp | |
380 | .nf | |
381 | /etc/dev.d/$(DEVNAME)/*.dev | |
382 | /etc/dev.d/$(SUBSYSTEM)/*.dev | |
383 | /etc/dev.d/default/*.dev | |
384 | .fi | |
04db8c9e GKH |
385 | .SH "FILES" |
386 | .nf | |
04db8c9e | 387 | /sbin/udev udev program |
4865de44 | 388 | /etc/udev/* udev config files |
04db8c9e | 389 | /etc/hotplug.d/default/udev.hotplug hotplug symlink to udev program |
fc238cff | 390 | /etc/dev.d/* programs invoked by udev |
04db8c9e GKH |
391 | .fi |
392 | .LP | |
393 | .SH "SEE ALSO" | |
05c0c9da | 394 | .BR udevinfo (8), |
bef370d6 | 395 | .BR udevd (8), |
eb13ff87 | 396 | .BR hotplug (8) |
04db8c9e GKH |
397 | .PP |
398 | The | |
758f236f | 399 | .I http://linux\-hotplug.sourceforge.net/ |
04db8c9e GKH |
400 | web site. |
401 | .SH AUTHORS | |
da86c7f0 KS |
402 | .B udev |
403 | was developed by Greg Kroah-Hartman <greg@kroah.com> with much help from | |
fc1f0d43 GKH |
404 | Dan Stekloff <dsteklof@us.ibm.com>, Kay Sievers <kay.sievers@vrfy.org>, and |
405 | many others. |