.B udev
reads the sysfs directory of the given device to collect device attributes
like label, serial number or bus device number.
-These attributes are treated as a key
+These attributes are treated as a key
to determine a unique name for device file creation.
.B udev
maintains a database for devices present on the system.
.I /etc/udev/udev.rules
or specified by the
.I udev_rules
-value in the
+value in the
.I /etc/udev/udev.conf
file.
.P
where valid methods with corresponding keys are:
.TP
.B CALLOUT
-calling external program, that returns a string to match
+calling external program, that returns a string to match. The
+.BR BUS
+key is optional, but if specified, the sysfs device bus must be able to be
+detemined by a "device" symlink.
.br
.RB "keys: " BUS ", " PROGRAM ", " ID
.TP
.B LABEL
device label or serial number, like USB serial number, SCSI UUID or
-file system label
+file system label. Up to 5 different sysfs files can be checked, with
+all of the values being required in order to match the rule.
.br
-.RB "keys: " BUS ", "
-.I sysfs_attribute
+.RB "keys: " BUS ", " SYSFS_
.TP
.B NUMBER
device number on the bus, like PCI bus id
.B REPLACE
string replacement of the kernel device name
.br
-.RB "key: " KERNEL_NAME
+.RB "key: " KERNEL
.P
The methods are applied in the following order:
.BR CALLOUT ", " LABEL ", " NUMBER ", " TOPOLOGY ", " REPLACE "."
The "kernel number" of the device.
for example, 'sda3' has a "kernel number" of '3'
.TP
+.B %k
+The "kernel name" for the device.
+.TP
.B %M
The kernel major number for the device.
.TP
CALLOUT, BUS="scsi", PROGRAM="/sbin/scsi_id", ID="OEM 0815", NAME="disk1"
# USB printer to be called lp_color
-LABEL, BUS="usb", serial="W09090207101241330", NAME="lp_color"
+LABEL, BUS="usb", SYSFS_serial="W09090207101241330", NAME="lp_color"
+
+# SCSI disk with a specific vendor and model number is to be called boot
+LABEL, BUS="scsi", SYSFS_vendor="IBM", SYSFS_model="ST336", NAME="boot%n"
# sound card with PCI bus id 00:0b.0 to be called dsp
NUMBER, BUS="pci", ID="00:0b.0", NAME="dsp"
REPLACE, KERNEL="ttyUSB1", NAME="pda", SYMLINK="palmtop handheld"
# multiple USB webcams with symlinks to be called webcam0, webcam1, ...
-LABEL, BUS="usb", model="WebCam V3", NAME="video%n", SYMLINK="webcam%n"
+LABEL, BUS="usb", SYSFS_model="XV3", NAME="video%n", SYMLINK="webcam%n"
.fi
.P
Permissions and ownership for the created device files may specified at