.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.
.B udev
queries the internal database for the name of the device file to be deleted.
.SH "CONFIGURATION"
+All
.B udev
-expects its configuration at
-.I /etc/udev/udev.config.
-The file consists of a set of lines. All empty lines and
-lines beginning with a '#' will be ignored.
+configuration files consist of a set of lines of text. All empty
+lines, and lines beginning with a '#' will be ignored.
+.P
+
+.B udev
+expects its main configuration file at
+.I /etc/udev/udev.conf.
+The file consists of a set of variables and values that allow the user to
+override default udev values. The current set of variables that can be
+overridden in this file is:
+.TP
+.B udev_root
+This is the where in the filesystem to place the device nodes. The default
+value for this is
+.I /udev/
+.TP
+.B udev_db
+The name and location of the udev database. The default value for this is
+.I /udev/.udev.tdb
+.TP
+.B udev_rules
+This is the location of the udev rules file. The default value for this is
+.I /etc/udev/udev.rules
+.TP
+.B udev_permissions
+This is the location of the udev permission file. The default value for this is
+.I /etc/udev/udev.permissions
+.TP
+.B default_mode
+This is the default mode for all nodes that have no explicit match in the
+permissions file. The default value for this is
+.I 0666
+.br
+.P
+.RI "A sample " udev.conf " might look like this:
+.sp
+.nf
+# udev_root - where in the filesystem to place the device nodes
+udev_root="/udev/"
+
+# udev_db - The name and location of the udev database.
+udev_db="/udev/.udev.tdb"
+
+# udev_rules - The name and location of the udev rules file
+udev_rules="/etc/udev/udev.rules"
+
+# udev_permissions - The name and location of the udev permission file
+udev_permissions="/etc/udev/udev.permissions"
+
+# default_mode - set the default mode for all nodes that have no
+# explicit match in the permissions file
+default_mode="0666"
+.fi
+.P
+The rules for udev to use when naming devices may specified at
+.I /etc/udev/udev.rules
+or specified by the
+.I udev_rules
+value in the
+.I /etc/udev/udev.conf
+file.
+.P
+Every line in the rules file define the mapping between device attributes and
+the device file name. It starts with a keyword defining the method used to
+match, followed by one ore more keys to compare and the filename for the
+device. One ore more optional symlinks targeting the node may be specified.
.br
-Every line defines the mapping between device attributes and the device file
-name. It starts with a keyword defining the method used to match, followed by
-one ore more keys to compare and the filename for the device. If no matching
-configuration is found, the default kernel device name is used.
+If no matching configuration is found, the default kernel device name
+is used.
.P
The line format is:
-.RS
.sp
-.I method, key,[key,...] name
+.I method, key,[key,...] name [, symlink]
.sp
-.RE
where valid methods with corresponding keys are:
.TP
+.B CALLOUT
+calling external program, that returns a string to match. The
+.B BUS
+key is optional, but if specified, the sysfs device bus must be able to be
+determined 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. The
+.B BUS
+key is optional, but if specified, the sysfs device bus must be able to be
+detemined by a "device" symlink.
.br
-keys: \fBBUS\fP, \fIsysfs_attribute\fP
+.RB "keys: " BUS ", " SYSFS_
.TP
.B NUMBER
device number on the bus, like PCI bus id
.br
-keys: \fBBUS\fP, \fBID\fP
+.RB "keys: " BUS ", " ID
.TP
.B TOPOLOGY
device position on bus, like physical port of USB device
.br
-keys: \fBBUS\fP, \fBPLACE\fP
+.RB "keys: " BUS ", " PLACE
.TP
.B REPLACE
string replacement of the kernel device name
.br
-key: \fBKERNEL_NAME\fP
+.RB "key: " KERNEL
+.P
+The methods are applied in the following order:
+.BR CALLOUT ", " LABEL ", " NUMBER ", " TOPOLOGY ", " REPLACE "."
+.P
+.RB "The " NAME " ," SYMLINK " and " PROGRAM
+fields support simple printf-like string substitution:
.TP
-.B CALLOUT
-calling external program, that returns a string to match
-.br
-keys: \fBBUS\fP, \fBPROGRAM\fP, \fBID\fP
+.B %n
+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
+.B %m
+The kernel minor number for the device.
+.TP
+.B %b
+The bus id for the device.
+.TP
+.B %c
+The CALLOUT program returned string.
+(This does not work within the PROGRAM field for the obvious reason.)
+.TP
+.B %D
+Use the devfs style disk name for this device.
+For partitions, this will result in 'part%n'
+If this is not a partition, it will result in 'disc'.
.P
-A sample \fIudev.conf\fP might look like this:
+.RI "A sample " udev.rules " might look like this:"
.sp
.nf
+# if /sbin/scsi_id returns "OEM 0815" device will be called disk1
+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"
# 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"
+# ttyUSB1 should always be called pda with two additional symlinks
+REPLACE, KERNEL="ttyUSB1", NAME="pda", SYMLINK="palmtop handheld"
-# if /sbin/scsi_id returns "OEM 0815" device will be called disk1
-CALLOUT, PROGRAM="/sbin/scsi_id" BUS="scsi", ID="OEM 0815" NAME="disk1"
+# multiple USB webcams with symlinks to be called webcam0, webcam1, ...
+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
-.I /etc/udev/udev.permissions.
-The file consists of a set of lines. All empty lines and
-lines beginning with a '#' will be ignored.
+.I /etc/udev/udev.permissions
+or specified by the
+.I udev_permission
+value in the
+.I /etc/udev/udev.conf
+file.
.br
-Every line lists a device name followed by owner, group and permission mode. All values are separated by colons.
+Every line lists a device name followed by owner, group and permission
+mode. All values are separated by colons. The name field may contain a
+pattern to apply the values to a whole class of devices.
+.br
+If
+.B udev
+was built using klibc or is used before the user database is accessible (e.g.
+.BR initrd "(4)), only numeric owner and group values may be used."
.sp
-A sample \fIudev.permissions\fP might look like this:
+.RI "A sample " udev.permissions " might look like this:"
.sp
.nf
#name:user:group:mode
-ttyUSB1:root:uucp:0666
+input/*:root:root:644
+ttyUSB1:0:8:0660
+video*:root:video:0660
dsp1:::0666
.fi
-
+.P
+A number of different fields in the above configuration files support a simple
+form of shell style pattern matching. It supports the following pattern characters:
+.TP
+.B *
+Matches zero, one, or more characters.
+.TP
+.B ?
+Matches any single character, but does not match zero characters.
+.TP
+.B [ ]
+Matches any single character specified within the brackets. For example, the
+pattern string "tty[SR]" would match either "ttyS" or "ttyR". Ranges are also
+supported within this match with the '-' character. For example, to match on
+the range of all digits, the pattern [0-9] would be used. If the first character
+following the '[' is a '!' then any character not enclosed is matched.
.SH "FILES"
.nf
-.ft B
-.ft
/sbin/udev udev program
-/etc/udev/* udev config and database files
+/etc/udev/* udev config files
/etc/hotplug.d/default/udev.hotplug hotplug symlink to udev program
.fi
.LP
.SH AUTHORS
.B udev
was developed by Greg Kroah-Hartman <greg@kroah.com> with much help from
-Dan Stekloff <dsteklof@us.ibm.com> and many others.
+Dan Stekloff <dsteklof@us.ibm.com>, Kay Sievers <kay.sievers@vrfy.org>, and
+many others.
~ianmdlvl / elogind.git / blobdiff