1 .TH UDEV 8 "October 2003" "" "Linux Administrator's Manual"
3 udev \- Linux configurable dynamic device naming support
5 .BI udev " hotplug-subsystem"
8 creates or removes device node files usually located in the /dev directory.
9 Its goal is to provide a dynamic device directory that contains only the files
10 for devices that are actually present.
16 is executed if a kernel device is added or removed from the system.
19 reads the sysfs directory of the given device to collect device attributes
20 like label, serial number or bus device number.
21 These attributes are treated as a key
22 to determine a unique name for device file creation.
24 maintains a database for devices present on the system.
28 queries the internal database for the name of the device file to be deleted.
31 expects its configuration at
32 .I /etc/udev/udev.config.
33 The file consists of a set of lines. All empty lines and
34 lines beginning with a '#' will be ignored.
36 Every line defines the mapping between device attributes and the device file
37 name. It starts with a keyword defining the method used to match, followed by
38 one ore more keys to compare and the filename for the device. If no matching
39 configuration is found, the default kernel device name is used.
44 .I method, key,[key,...] name
47 where valid methods with corresponding keys are:
50 device label or serial number, like USB serial number, SCSI UUID or
53 keys: \fBBUS\fP, \fIsysfs_attribute\fP
56 device number on the bus, like PCI bus id
58 keys: \fBBUS\fP, \fBID\fP
61 device position on bus, like physical port of USB device
63 keys: \fBBUS\fP, \fBPLACE\fP
66 string replacement of the kernel device name
68 key: \fBKERNEL_NAME\fP
71 calling external program, that returns a string to match
73 keys: \fBBUS\fP, \fBPROGRAM\fP, \fBID\fP
75 The name field supports simple printf-like string subtitution:
79 the "kernel number" of the device
80 for example, 'sda3' has a "kernel number" of '3'
83 the kernel major number for the device
86 the kernel minor number for the device
89 the bus id for the device
92 A sample \fIudev.conf\fP might look like this:
95 # USB printer to be called lp_color
96 LABEL, BUS="usb", serial="W09090207101241330", NAME="lp_color"
98 # sound card with PCI bus id 00:0b.0 to be called dsp
99 NUMBER, BUS="pci", ID="00:0b.0", NAME="dsp"
101 # USB mouse at third port of the second hub to be called mouse1
102 TOPOLOGY, BUS="usb", PLACE="2.3", NAME="mouse1"
104 # ttyUSB1 should always be called pda
105 REPLACE, KERNEL="ttyUSB1", NAME="pda"
107 # if /sbin/scsi_id returns "OEM 0815" device will be called disk1
108 CALLOUT, BUS="scsi", PROGRAM="/sbin/scsi_id", ID="OEM 0815", NAME="disk1"
110 # USB webcams to be called webcam0, webcam1, ...
111 LABEL, BUS="usb", model="WebCam Version 3", NAME="webcam%n"
114 Permissions and ownership for the created device files may specified at
115 .I /etc/udev/udev.permissions.
116 The file consists of a set of lines. All empty lines and
117 lines beginning with a '#' will be ignored.
119 Every line lists a device name followed by numeric owner, group and permission
120 mode. All values are separated by colons. The name field may end with a
121 wildcard to apply the values to a whole class of devices.
123 A sample \fIudev.permissions\fP might look like this:
126 #name:user:group:mode
136 /sbin/udev udev program
137 /etc/udev/* udev config and database files
138 /etc/hotplug.d/default/udev.hotplug hotplug symlink to udev program
145 .I http://linux-hotplug.sourceforge.net/
149 was developed by Greg Kroah-Hartman <greg@kroah.com> with much help from
150 Dan Stekloff <dsteklof@us.ibm.com> and many others.