.TH UDEV 8 "October 2003" "" "Linux Administrator's Manual"
.SH NAME
udev \- Linux configurable dynamic device naming support
.SH SYNOPSIS
.B udev
.SH "DESCRIPTION"
.B udev
creates or removes device node files usually located in the /dev directory.
As part of the
.B hotplug
subsystem,
.B udev
is exectuted if a kernel device is added or removed from the system.
.P
On device creation,
.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 passed as a key to the namedev subsystem
to receive a unique name for device file creation.
namedev maintains a database for devices present on the system.
.P
On device removal,
.B udev
queries the namedev database for the name of the device file to delete.
.P
namedev expects its configuration at
.I /etc/udev/namedev.config.
The file consists of a set of lines. All empty lines and
lines beginning with a '#' will be ignored.
.br
Every line defines the mapping between device attributes and the name of
the device file. It starts with a keyword defining the method for
overriding the default kernel naming scheme, followed by a list
of keys and ends with the definition of the filename for the device.
.TP
.B LABEL
device label or serial number, like USB serial number, SCSI UUID or
file system label
.TP
.B NUMBER
device number on the bus, like PCI bus id
.TP
.B TOPOLOGY
device position on bus, like physical port of USB device
.TP
.B REPLACE
string replacement of the kernel device name
.P
If no matching configuration is found, the default kernel device name is used.
.SH "EXAMPLE"
.nf
# USB printer to be called lp_color
LABEL, BUS="usb", serial="W09090207101241330", NAME="lp_color"

# sound card with PCI bus id 00:0b.0 to be called dsp
NUMBER, BUS="pci", id="00:0b.0", NAME="dsp"

# USB mouse at third port of the second hub to be called mouse1
TOPOLOGY, BUS="usb", place="2.3", NAME="mouse1"

# ttyUSB1 should always be called pda
REPLACE, KERNEL="ttyUSB1", NAME="pda"
.fi
.SH "FILES"
.nf
.ft B
.ft
/sbin/udev                           udev program
/etc/udev/*                          udev config and database files
/etc/hotplug.d/default/udev.hotplug  hotplug symlink to udev program
.fi
.LP
.SH "SEE ALSO"
.B hotplug (8)
.PP
The
.I http://linux-hotplug.sourceforge.net/
web site.
.SH AUTHORS
udev was developed by Greg Kroah-Hartman <greg@kroah.com> with much help from
Dan Stekloff <dsteklof@us.ibm.com> and many others.