.B DEVPATH
The sysfs devpath of the device without the mountpoint but a leading slash.
.P
-Additional optional environment variables are:
+Additional optional environment variables:
.TP
.B UDEV_CONFIG_FILE
Overrides the default location of the
.SH "DESCRIPTION"
.B udev
creates or removes device node files usually located in the /dev directory.
-It provides a dynamic device directory that contains only the files for
-devices that are actually present.
+It provides a dynamic device directory contaning only the files for
+actually present devices.
.P
As part of the
.B hotplug
.B udev
reads the sysfs directory of the given device to collect device attributes
like label, serial number or bus device number.
-These attributes may used as keys to determine a
+These attributes may be used as keys to determine a
unique name for device file creation.
.B udev
maintains a database for devices present on the system.
All
.B udev
configuration files consist of a set of lines of text. All empty
-lines, and lines beginning with a '#' will be ignored.
+lines and lines beginning with a '#' will be ignored.
.P
.B udev
expects its main configuration file at
.IR /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:
+The file consists of a set of variables and values allowing the user to
+override default udev values. The following variables can be overridden
+in this file:
.TP
.B udev_root
-This is the where in the filesystem to place the device nodes. The default
-value for this is
+Indicates where to place the device nodes in the filesystem. The default
+value is
.IR /udev/ .
.TP
.B udev_db
-The name and location of the udev database. The default value for this is
+The name and location of the udev database. The default value is
.IR /udev/.udev.tdb .
.TP
.B udev_rules
-This is the location of the udev rules file. The default value for this is
+This is the location of the udev rules file. The default value for this is
.IR /etc/udev/udev.rules .
If a directory is specified, the whole directory is
scanned for files ending with
.TP
.B udev_log
If you want udev to log some information to the syslog for every node created or
-removed. The default value for this is
+removed. The default value is
.IR yes .
.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
+This is the default mode for all nodes not explicitely matching in the
+permissions file. The default value is
.IR 0666 .
.TP
.B default_owner
-This is the default owner for all nodes that have no explicit match in the
-permissions file. The default value for this is
+This is the default owner for all nodes not explicitely matching in the
+permissions file. The default value is
.IR root .
.TP
.B default_group
-This is the default group for all nodes that have no explicit match in the
-permissions file. The default value for this is
+This is the default group for all nodes not explicitely matching in the
+permissions file. The default value is
.IR root .
.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 - where to place the device nodes in the filesystem
udev_root="/udev/"
-# udev_db - The name and location of the udev database.
+# udev_db - The name and location of the udev database
udev_db="/udev/.udev.tdb"
# udev_rules - The location of the directory where to look for files
# udev_log - set to "yes" if you want logging, else "no"
udev_log="yes"
-# default_mode - set the default mode for all nodes that have no
-# explicit match in the permissions file
+# default_mode - set the default mode for all nodes not
+# explicitely matching in the permissions file
default_mode="0666"
-# default_owner - set the default owner for all nodes that have no
-# explicit match in the permissions file
+# default_owner - set the default owner for all nodes not
+# explicitely matching in the permissions file
default_owner="root"
-# default_group - set the default group for all nodes that have no
-# explicit match in the permissions file
+# default_group - set the default group for all nodes not
+# explicitely matching in the permissions file
default_group="root"
.fi
.P
-The rules for udev to use when naming devices may specified at
+The rules for udev to use when naming devices may specified in
.I /etc/udev/udev.rules
-or specified by the
+or by the
.I udev_rules
value in the
.I /etc/udev/udev.conf
.sp
.IR "key " ,[ "key " ,...] " name " [, " symlink" ]
.sp
-where possible fields are:
+where fields are:
.TP
.B BUS
Match the bus type of the device.
.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.
+all of the values being required to match the rule.
+.br
+Trailing whitespace characters in the sysfs attribute value are ignored, if
+the key doesn't have any trailing whitespace characters by itself.
.TP
.B PROGRAM
Call external program. This key is valid if the program returns successful.
.B udev
are also available for the program.
.br
-The string returned by the program may additionally matched with the
+The string returned by the program may be 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
+call. This key may be used in any following rule after a
.B PROGRAM
call.
.TP
.B NAME
-The name of the node to be created. If the name field is omitted or its
-value is empty, the device will be ignored and no node will be created.
+The name of the node to be created.
.br
If given with the attribute
.BR NAME{ all_partitions }
.B SYMLINK
The name of a symlink targeting the node. Multiple symlinks may be
specified by separating the names by the space character.
+.br
+If both the name and the symlink fields are omitted or its
+values empty, the device will be ignored and no node will be created.
+.br
+If only the symlink field is given and the name field is omitted,
+the rule will not be applied immediatly, but the symlink field is added
+to the symlink list of the rule which will create the node.
+This makes it possible to specify additional symlinks in a possibly
+separate rules file, while the device nodes are maintained by the
+distribution provided rules file.
.P
.RB "The " NAME " ," SYMLINK " and " PROGRAM
fields support simple printf-like string substitution:
The bus id for the device.
.TP
.B %c
-The
+The string returned from the execution of
.B PROGRAM
-returned string.
(This does not work within the
.B PROGRAM
field for the obvious reason.)
.br
-A single part of the string, separated by the space character
-my be selected by specifying the part number as a attribute:
+A single part of the string, separated by a space character
+may be selected by specifying the part number as a attribute:
.BI %c{ part }
.TP
.BI %s{ filename }
# USB printer to be called lp_color
BUS="usb", SYSFS{serial}="W09090207101241330", NAME="lp_color"
-# SCSI disk with a specific vendor and model number is to be called boot
+# SCSI disk with a specific vendor and model number will 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
BUS="usb", SYSFS{model}="XV3", NAME="video%n", SYMLINK="webcam%n"
.fi
.P
-Permissions and ownership for the created device files may specified at
+Permissions and ownership for the created device files may specified in
.I /etc/udev/udev.permissions
-or specified by the
+or by the
.I udev_permission
value in the
.I /etc/udev/udev.conf
.P
The value
.I $local
-can be substituted for a specific username. In that case, udev will determine
+can be used instead of a specific username. In that case, udev will determine
the current local user at the time of device node creation and substitute
that username as the owner of the new device node. This is useful, for
example, to let hot-plugged devices, such as cameras, be owned by the user at
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.
+following the '[' is a '!', any character not enclosed is matched.
.SH "FILES"
.nf
/sbin/udev udev program
~ianmdlvl / elogind.git / blobdiff