.SH NAME
udev \- Linux configurable dynamic device naming support
.SH SYNOPSIS
+.BI udev " hotplug-subsystem"
+.br
.B udev
+.RI "[-q " query_type " -p " sysfs_path "] [-drVh]"
.SH "DESCRIPTION"
.B udev
creates or removes device node files usually located in the /dev directory.
+Its goal is to provide a dynamic device directory that contains only the files
+for devices that are actually present.
+.P
As part of the
.B hotplug
subsystem,
.B udev
-is exectuted if a kernel device is added or removed from the system.
-.P
+is executed if a kernel device is added or removed from the system.
On device creation,
.B udev
-reads the sysfs directory of the given device, to collect device attributes
+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
+These attributes may used as keys to determine a
+unique name for device file creation.
+.B udev
+maintains a database for devices present on the system.
+.br
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.
+queries its database for the name of the device file to be deleted.
+.SH "OPTIONS"
+.B udev
+normally is called by
+.B hotplug
+with the subsystem as argument and various environment variables set.
.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, optional ownwership and permission settings and
-the filename for the device. If no matching configuration is found,
-the default kernel device name is used.
+It may also called with the following options:
+.TP
+.B -V
+Print the version information.
+.TP
+.B -r
+Print the the
+.B udev_root
+directory. When used in conjunction with a query for the node name, the
+.B udev_root
+will be prepended.
+.TP
+.BI -q " query_type"
+Query the database for specified value of a created device node.
+Valid types are:
+.BR name ", " symlink ", " owner " or " group .
+.TP
+.BI -p " sysfs_path"
+Specify the sysfs path needed for the query.
+.TP
+.B -d
+Dump the whole database.
+.TP
+.B -h
+Print help text.
+.SH "CONFIGURATION"
+All
+.B udev
+configuration files consist of a set of lines of text. All empty
+lines, and lines beginning with a '#' will be ignored.
.P
-.I method, key,[key,...] [owner,] [group,] [mode,] name
+
+.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 LABEL
-device label or serial number, like USB serial number, SCSI UUID or
-file system label
-.br
-keys: \fBBUS\fP, \fIsysfs_attribute\fP
+.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 NUMBER
-device number on the bus, like PCI bus id
-.br
-keys: \fBBUS\fP, \fBID\fP
+.B udev_db
+The name and location of the udev database. The default value for this is
+.I /udev/.udev.tdb
.TP
-.B TOPOLOGY
-device position on bus, like physical port of USB device
-.br
-keys: \fBBUS\fP, \fBPLACE\fP
+.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 REPLACE
-string replacement of the kernel device name
-.br
-key: \fBKERNEL_NAME\fP
+.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 CALLOUT
-calling external program, that returns a string to match
+.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
-keys: \fBBUS\fP, \fBPROGRAM\fP, \fBID\fP
-.SH "EXAMPLE"
+.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 defines the mapping between device attributes
+and the device file name. One ore more keys are specified to match a rule
+with the current device. If all keys are matching, the rule will be applied
+and the name is used for the device node. One or more optional symlinks
+targeting the node may be specified.
+.br
+If no matching rule is found, the default kernel device name is used.
+.P
+The line format is:
+.sp
+.I key,[key,...] name [, symlink]
+.sp
+where keys are:
+.TP
+.B BUS
+Match the bus type of the device.
+(The sysfs device bus must be able to be determined by a "device" symlink.)
+.TP
+.B KERNEL
+Match the kernel device name.
+.TP
+.B ID
+Match the device number on the bus, like PCI bus id.
+.TP
+.B PLACE
+Match the topological position on bus, like physical port of USB device
+.TP
+.BI SYSFS_ filename
+Match sysfs device attribute like label, vendor, USB serial number, SCSI UUID
+or 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.
+.TP
+.B PROGRAM
+Call external program. This key is valid if the program returns successful.
+The string returned by the program may additionally matched with the
+.B RESULT
+key.
+.TP
+.B RESULT
+Match the returned string of the last
+.B PROGRAM
+call. This key may used in any following rule after a
+.B PROGRAM
+call.
+.P
+.RB "The " NAME " ," SYMLINK " and " PROGRAM
+fields support simple printf-like string substitution:
+.TP
+.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
+.B PROGRAM
+returned string.
+(This does not work within the
+.B 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
+.RI "A sample " udev.rules " might look like this:"
+.sp
+.nf
+# if /sbin/scsi_id returns "OEM 0815" device will be called disk1
+BUS="scsi", PROGRAM="/sbin/scsi_id", RESULT="OEM 0815", NAME="disk1"
+
# USB printer to be called lp_color
-LABEL, BUS="usb", serial="W09090207101241330", NAME="lp_color"
+BUS="usb", SYSFS_serial="W09090207101241330", NAME="lp_color"
+
+# SCSI disk with a specific vendor and model number is to be called boot
+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"
+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"
+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
+KERNEL="ttyUSB1", NAME="pda", SYMLINK="palmtop handheld"
-# if /sbin/dev_id returns "V0815" device will be called dev0815
-CALLOUT, PROGRAM="/sbin/dev_id", BUS="pci", ID="V0815", NAME="dev0815"
+# multiple USB webcams with symlinks to be called webcam0, webcam1, ...
+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
+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. 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
+.RI "A sample " udev.permissions " might look like this:"
+.sp
+.nf
+#name:user:group:mode
+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 "SEE ALSO"
-.B hotplug (8)
+.BR 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.
+.B udev
+was developed by Greg Kroah-Hartman <greg@kroah.com> with much help from
+Dan Stekloff <dsteklof@us.ibm.com>, Kay Sievers <kay.sievers@vrfy.org>, and
+many others.
~ianmdlvl / elogind.git / blobdiff