udev \- Linux configurable dynamic device naming support
.SH SYNOPSIS
.BI udev " hotplug-subsystem"
-.br
+.P
+The environment must provide the following variables:
+.TP
+.B ACTION
+.IR add " or " remove
+signifies the connection or disconnection of a device.
+.TP
+.B DEVPATH
+The sysfs devpath of the device without the mountpoint but a leading slash.
+.P
+Additional optional environment variables:
+.TP
+.B UDEV_CONFIG_FILE
+Overrides the default location of the
+.B udev
+config file.
+.TP
+.B UDEV_NO_SLEEP
+The default behavior of
+.B udev
+is to wait until all the sysfs files of the device chain are populated. If set,
+.B udev
+will continue, regardless of the state of the device representation.
+.TP
+.B UDEV_NO_DEVD
+The default behavior of
.B udev
-.RI "[-q " query_type " -p " sysfs_path "] [-drVh]"
+is to execute programs in the
+.I /etc/dev.d/
+directory after device handling. If set,
+.B udev
+will skip this step.
.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.
+provides a dynamic device directory containing only the files for actually
+present devices. It creates or removes device node files usually located in
+the /dev directory, or it renames network interfaces.
+.br
+
.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
-unique name for device file creation.
+These attributes may be used as keys to determine a
+unique name for the device.
.B udev
maintains a database for devices present on the system.
.br
On device removal,
.B udev
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
-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 -q
-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.
+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:
+.IR /etc/udev/udev.conf .
+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
-.I /udev/
+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
-.I /udev/.udev.tdb
+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
-.I /etc/udev/udev.rules
+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
+.I .rules
+and all rule files are read in lexical order.
.TP
.B udev_permissions
-This is the location of the udev permission file. The default value for this is
-.I /etc/udev/udev.permissions
+This is the location of the udev permission file. The default value for this is
+.IR /etc/udev/udev.permissions .
+If a directory is specified, the whole directory is scanned for files ending with
+.I .permissions
+and all permission files are read in lexical order.
+.TP
+.B udev_log
+If you want udev to log some information to the syslog for every device handled.
+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
-.I 0666
+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 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 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 name and location of the udev rules file
-udev_rules="/etc/udev/udev.rules"
+# udev_rules - The location of the directory where to look for files
+ which names ending with .rules
+udev_rules="/etc/udev/"
# 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
+# udev_log - set to "yes" if you want logging, else "no"
+udev_log="yes"
+
+# 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 not
+# explicitely matching in the permissions file
+default_owner="root"
+
+# 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
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.
+and the device name. One or 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 to name the device file or the network interface.
.br
If no matching rule is found, the default kernel device name is used.
.P
-The line format is:
+Every rule consists of a list of comma separated fields:
.sp
-.I key,[key,...] name [, symlink]
+.IR "key " ,[ "key " ,...] " name " [, " symlink" ]
.sp
-where keys are:
+where fields are:
.TP
.B BUS
Match the bus type of the device.
.B PLACE
Match the topological position on bus, like physical port of USB device
.TP
-.BI SYSFS_ filename
+.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.
-The string returned by the program may additionally matched with the
+The environment variables of
+.B udev
+are also available for the program.
+.br
+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, or the name, the network interface
+should be renamed to.
+.br
+If given with the attribute
+.BR NAME{ all_partitions }
+it will create all 15 partitions of a blockdevice.
+This may be useful for removable media devices.
+.TP
+.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.
+.TP
+.B OWNER, GROUP, MODE
+The permissions for this device. Every specified value overwrites the value
+given in the permissions file.
.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'
+For example, 'sda3' has a "kernel number" of '3'.
.TP
.B %k
The "kernel name" for the device.
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.)
+The string returned from the execution of
+.B PROGRAM
+(This does not work within the
+.B PROGRAM
+field for the obvious reason.)
+.br
+A single part of the string, separated by a space character
+may be selected by specifying the part number as an attribute:
+.BI %c{ N }
+If the number is followed by the + char this part plus
+all remaining parts of the result string are substituted:
+.BI %c{ N+ }
+.TP
+.BI %s{ filename }
+The content of a sysfs attribute.
.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'.
+.B %%
+The '%' character itself.
+.P
+The count of charcters to insert may be limited by specifying
+the format length value. For example, '%3s{file}' will only insert
+the first three characters of the sysfs attribute.
.P
.RI "A sample " udev.rules " might look like this:"
.sp
BUS="scsi", PROGRAM="/sbin/scsi_id", RESULT="OEM 0815", NAME="disk1"
# USB printer to be called lp_color
-BUS="usb", SYSFS_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"
+# 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="pci", ID="00:0b.0", NAME="dsp"
KERNEL="ttyUSB1", NAME="pda", SYMLINK="palmtop handheld"
# multiple USB webcams with symlinks to be called webcam0, webcam1, ...
-BUS="usb", SYSFS_model="XV3", NAME="video%n", SYMLINK="webcam%n"
+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
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
dsp1:::0666
.fi
.P
+The value
+.I $local
+can be used instead of a specific username. In that case, udev will determine
+the current local user at the time of device node creation and substitute
+that username as the owner of the new device node. This is useful, for
+example, to let hot-plugged devices, such as cameras, be owned by the user at
+the current console. Note that if no user is currently logged in, or if udev
+otherwise fails to determine a current user, the
+.I default_owner
+value is used in lieu.
+.P
A number of different fields in the above configuration files support a simple
form of shell style pattern matching. It supports the following pattern characters:
.TP
.B [ ]
Matches any single character specified within the brackets. For example, the
pattern string "tty[SR]" would match either "ttyS" or "ttyR". Ranges are also
-supported within this match with the '-' character. For example, to match on
-the range of all digits, the pattern [0-9] would be used. If the first character
-following the '[' is a '!' then any character not enclosed is matched.
+supported within this match with the '\-' character. For example, to match on
+the range of all digits, the pattern [0\-9] would be used. If the first character
+following the '[' is a '!', any character not enclosed is matched.
+.P
+After device node creation, removal, or network device renaming,
+.B udev
+executes the programs in the directory tree under
+.IR /etc/dev.d/ .
+The name of a program must end with
+.I .dev
+suffix, to be recognized.
+.br
+In addition to the hotplug environment variables,
+.B DEVNAME
+is exported to make the name of the created node, or the name the network
+device is renamed to, available to the executed program. The programs in every
+directory are sorted in lexical order, while the directories are searched in
+the following order:
+.sp
+.nf
+/etc/dev.d/$(DEVNAME)/*.dev
+/etc/dev.d/$(SUBSYSTEM)/*.dev
+/etc/dev.d/default/*.dev
+.fi
.SH "FILES"
.nf
/sbin/udev udev program
/etc/udev/* udev config files
/etc/hotplug.d/default/udev.hotplug hotplug symlink to udev program
+/etc/dev.d/* programs invoked by udev
.fi
.LP
.SH "SEE ALSO"
+.BR udevinfo (8),
+.BR udevd (8),
.BR hotplug (8)
.PP
The
-.I http://linux-hotplug.sourceforge.net/
+.I http://linux\-hotplug.sourceforge.net/
web site.
.SH AUTHORS
.B udev
~ianmdlvl / elogind.git / blobdiff