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On Mon, 2004-09-06 at 17:45 +0200, Kay Sievers wrote: > On Mon, 2004-09-06 at 16:46 +0200, David Zeuthen wrote: > > Nice, I like it. It's a easy way to group device nodes of the same type, > but coming from different kernel subsystems. > That's a good way of putting it, yeah. > > Here's a patch against udev-030 that can help create compatibility > > symlinks like /dev/cdrom, /dev/cdrom1 etc. The patch introduces a new > > substitution type %C (for Compatibility) that can be used as follows > > I suggest using %e for enumeration here, cause "compatibility" can > easily be misunderstood. > Good point, I've changed that. > And we need a few lines added to the man page at udev.8.in :) > Done. I've also added an example. Also, Kay pointed out offlist that the rules can be written to not require a shell script; this actually works KERNEL="sr*", NAME="%k", SYMLINK="cdrom%e" KERNEL="scd*", NAME="%k", SYMLINK="cdrom%e" KERNEL="pcd*", NAME="%k", SYMLINK="cdrom%e" KERNEL="hd[a-z]", PROGRAM="/bin/cat /proc/ide/%k/media", RESULT="cdrom", NAME="\%k", SYMLINK="cdrom%e" KERNEL="fd[0-9]", NAME="%k", SYMLINK="floppy%e" KERNEL="hd[a-z]", PROGRAM="/bin/cat /proc/ide/%k/media", RESULT="floppy", NAME=\"%k", SYMLINK="floppy%e" New patch is attached. David
413 lines
12 KiB
Groff
413 lines
12 KiB
Groff
.TH UDEV 8 "October 2003" "" "Linux Administrator's Manual"
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.SH NAME
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udev \- Linux configurable dynamic device naming support
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.SH SYNOPSIS
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.BI udev " hotplug-subsystem"
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.P
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The environment must provide the following variables:
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.TP
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.B ACTION
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.IR add " or " remove
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signifies the connection or disconnection of a device.
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.TP
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.B DEVPATH
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The sysfs devpath of the device without the mountpoint but a leading slash.
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.P
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Additional optional environment variables:
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.TP
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.B UDEV_CONFIG_FILE
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Overrides the default location of the
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.B udev
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config file.
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.TP
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.B UDEV_NO_SLEEP
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The default behavior of
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.B udev
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is to wait until all the sysfs files of the device chain are populated. If set,
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.B udev
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will continue, regardless of the state of the device representation.
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.TP
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.B UDEV_NO_DEVD
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The default behavior of
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.B udev
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is to execute programs in the
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.I /etc/dev.d/
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directory after device handling. If set,
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.B udev
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will skip this step.
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.SH "DESCRIPTION"
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.B udev
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provides a dynamic device directory containing only the files for actually
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present devices. It creates or removes device node files usually located in
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the /dev directory, or it renames network interfaces.
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.br
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.P
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As part of the
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.B hotplug
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subsystem,
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.B udev
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is executed if a kernel device is added or removed from the system.
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On device creation,
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.B udev
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reads the sysfs directory of the given device to collect device attributes
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like label, serial number or bus device number.
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These attributes may be used as keys to determine a
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unique name for the device.
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.B udev
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maintains a database for devices present on the system.
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.br
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On device removal,
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.B udev
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queries its database for the name of the device file to be deleted.
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.SH "CONFIGURATION"
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All
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.B udev
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configuration files consist of a set of lines of text. All empty
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lines and lines beginning with a '#' will be ignored.
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.P
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.B udev
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expects its main configuration file at
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.IR /etc/udev/udev.conf .
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The file consists of a set of variables and values allowing the user to
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override default udev values. The following variables can be overridden
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in this file:
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.TP
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.B udev_root
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Indicates where to place the device nodes in the filesystem. The default
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value is
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.IR @udevdir@/ .
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.TP
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.B udev_db
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The name and location of the udev database. The default value is
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.IR @udevdir@/.udev.tdb .
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.TP
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.B udev_rules
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The name of the udev rules file or directory to look for files with the suffix
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.IR .rules .
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All rule files are read in lexical order. The default value is
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.IR /etc/udev/rules.d/ .
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.TP
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.B udev_permissions
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The name of the udev permission file or directory to look for files with the
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suffix
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.IR .permissions .
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All permission files are read in lexical order. The default value is
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.IR /etc/udev/permissions.d/ .
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.TP
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.B udev_log
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The switch, if udev logs some information for every device handled.
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The default value is
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.IR yes .
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.TP
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.B default_mode
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The default mode for all nodes not explicitely matching in the permissions
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file. The default value is
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.IR 0666 .
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.TP
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.B default_owner
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The default owner for all nodes not explicitely matching in the permissions
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file. The default value is
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.IR root .
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.TP
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.B default_group
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The default group for all nodes not explicitely matching in the permissions
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file. The default value is
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.IR root .
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.br
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.P
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.RI "A sample " udev.conf " might look like this:
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.sp
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.nf
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# udev_root - where to place the device nodes in the filesystem
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udev_root="/udev"
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# udev_db - The name and location of the udev database
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udev_db="/udev/.udev.tdb"
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# udev_rules - The name of the udev rules file or directory to look
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for files with the suffix .rules
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udev_rules="/etc/udev/rules.d/"
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# udev_permissions - The name of the udev permission file or directory
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to look for files with the suffix .permissions
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udev_permissions="/etc/udev/udev.permissions"
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# udev_log - set to "yes" if you want logging, else "no"
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udev_log="yes"
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# default_mode - set the default mode for all nodes not
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# explicitely matching in the permissions file
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default_mode="0666"
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# default_owner - set the default owner for all nodes not
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# explicitely matching in the permissions file
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default_owner="root"
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# default_group - set the default group for all nodes not
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# explicitely matching in the permissions file
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default_group="root"
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.fi
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.P
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The rules for device naming, are read from the files located in the
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.I /etc/udev/rules.d/
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directory, or at the location specified by the
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.I udev_rules
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value in the
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.I /etc/udev/udev.conf
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file.
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.br
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Every line in the rules file defines the mapping between device attributes
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and the device name. One or more keys are specified to match a rule with
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the current device. If all keys are matching, the rule will be applied and
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the name is used to name the device file or the network interface.
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.br
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If no matching rule is found, the default kernel device name is used.
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.P
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Every rule consists of a list of comma separated fields:
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.sp
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.IR "key " ,[ "key " ,...] " name " [, " symlink" ]
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.sp
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where fields are:
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.TP
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.B BUS
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Match the bus type of the device.
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(The sysfs device bus must be able to be determined by a "device" symlink.)
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.TP
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.B KERNEL
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Match the kernel device name.
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.TP
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.B ID
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Match the device number on the bus, like PCI bus id.
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.TP
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.B PLACE
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Match the topological position on bus, like physical port of USB device
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.TP
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.BI SYSFS{ filename }
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Match sysfs device attribute like label, vendor, USB serial number, SCSI UUID
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or file system label. Up to 5 different sysfs files can be checked, with
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all of the values being required to match the rule.
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.br
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Trailing whitespace characters in the sysfs attribute value are ignored, if
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the key doesn't have any trailing whitespace characters by itself.
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.TP
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.B PROGRAM
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Call external program. This key is valid if the program returns successful.
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The environment variables of
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.B udev
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are also available for the program.
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.br
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The string returned by the program may be additionally matched with the
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.B RESULT
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key.
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.TP
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.B RESULT
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Match the returned string of the last
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.B PROGRAM
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call. This key may be used in any following rule after a
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.B PROGRAM
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call.
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.TP
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.B NAME
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The name of the node to be created, or the name, the network interface
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should be renamed to.
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.br
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If given with the attribute
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.BR NAME{ all_partitions }
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it will create all 15 partitions of a blockdevice.
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This may be useful for removable media devices.
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.TP
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.B SYMLINK
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The name of a symlink targeting the node. Multiple symlinks may be
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specified by separating the names by the space character.
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.br
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If both the name and the symlink fields are omitted or its
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values empty, the device will be ignored and no node will be created.
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.br
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If only the symlink field is given and the name field is omitted,
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the rule will not be applied immediatly, but the symlink field is added
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to the symlink list of the rule which will create the node.
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This makes it possible to specify additional symlinks in a possibly
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separate rules file, while the device nodes are maintained by the
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distribution provided rules file.
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.TP
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.B OWNER, GROUP, MODE
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The permissions for this device. Every specified value overwrites the value
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given in the permissions file.
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.P
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.RB "The " NAME " ," SYMLINK " and " PROGRAM
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fields support simple printf-like string substitution:
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.TP
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.B %n
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The "kernel number" of the device.
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For example, 'sda3' has a "kernel number" of '3'.
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.TP
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.B %k
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The "kernel name" for the device.
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.TP
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.B %M
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The kernel major number for the device.
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.TP
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.B %m
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The kernel minor number for the device.
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.TP
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.B %b
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The bus id for the device.
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.TP
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.B %c
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The string returned from the execution of
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.B PROGRAM
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(This does not work within the
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.B PROGRAM
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field for the obvious reason.)
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.br
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A single part of the string, separated by a space character
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may be selected by specifying the part number as an attribute:
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.BI %c{ N }
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If the number is followed by the + char this part plus
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all remaining parts of the result string are substituted:
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.BI %c{ N+ }
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.TP
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.BI %s{ filename }
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The content of a sysfs attribute.
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.TP
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.B %e
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If a device node already exists with the name, the smallest positive
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decimal integer N is substituted such that the resulting name doesn't
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match an existing device node. Otherwise nothing is substituted. This
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can be used to create compatibility symlinks and enumerate devices of
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the same type originating from different kernel subsystems.
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.TP
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.B %%
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The '%' character itself.
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.P
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The count of charcters to insert may be limited by specifying
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the format length value. For example, '%3s{file}' will only insert
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the first three characters of the sysfs attribute.
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.P
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.RI "A sample " udev.rules " might look like this:"
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.sp
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.nf
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# if /sbin/scsi_id returns "OEM 0815" device will be called disk1
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BUS="scsi", PROGRAM="/sbin/scsi_id", RESULT="OEM 0815", NAME="disk1"
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# USB printer to be called lp_color
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BUS="usb", SYSFS{serial}="W09090207101241330", NAME="lp_color"
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# SCSI disk with a specific vendor and model number will be called boot
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BUS="scsi", SYSFS{vendor}="IBM", SYSFS{model}="ST336", NAME="boot%n"
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# sound card with PCI bus id 00:0b.0 to be called dsp
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BUS="pci", ID="00:0b.0", NAME="dsp"
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# USB mouse at third port of the second hub to be called mouse1
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BUS="usb", PLACE="2.3", NAME="mouse1"
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# ttyUSB1 should always be called pda with two additional symlinks
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KERNEL="ttyUSB1", NAME="pda", SYMLINK="palmtop handheld"
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# multiple USB webcams with symlinks to be called webcam0, webcam1, ...
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BUS="usb", SYSFS{model}="XV3", NAME="video%n", SYMLINK="webcam%n"
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# grouping of optical drives from multiple kernel subsystems
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KERNEL="sr*", NAME="%k", SYMLINK="cdrom%e"
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KERNEL="scd*", NAME="%k", SYMLINK="cdrom%e"
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KERNEL="pcd*", NAME="%k", SYMLINK="cdrom%e"
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KERNEL="hd[a-z]", PROGRAM="/bin/cat /proc/ide/%k/media", RESULT="cdrom",
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NAME="%k", SYMLINK="cdrom%e"
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.fi
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.P
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The permissions and ownership of the created device file is read from
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the files located in the
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.I /etc/udev/permissions.d/
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directory, or at the location specified by the
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.I udev_permission
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value in the
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.I /etc/udev/udev.conf
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file.
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.br
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Every line lists a device name followed by owner, group and permission
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mode. All values are separated by colons. The name field may contain a
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pattern to apply the values to a whole class of devices.
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.sp
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.RI "A sample " udev.permissions " might look like this:"
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.sp
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.nf
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#name:user:group:mode
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input/*:root:root:644
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ttyUSB1:0:8:0660
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video*:root:video:0660
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dsp1:::0666
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.fi
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.P
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The value
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.I $local
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can be used instead of a specific username. In that case, udev will determine
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the current local user at the time of device node creation and substitute
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that username as the owner of the new device node. This is useful, for
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example, to let hot-plugged devices, such as cameras, be owned by the user at
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the current console. Note that if no user is currently logged in, or if udev
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otherwise fails to determine a current user, the
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.I default_owner
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value is used in lieu.
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.P
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A number of different fields in the above configuration files support a simple
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form of shell style pattern matching. It supports the following pattern characters:
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.TP
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.B *
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Matches zero, one, or more characters.
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.TP
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.B ?
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Matches any single character, but does not match zero characters.
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.TP
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.B [ ]
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Matches any single character specified within the brackets. For example, the
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pattern string "tty[SR]" would match either "ttyS" or "ttyR". Ranges are also
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supported within this match with the '\-' character. For example, to match on
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the range of all digits, the pattern [0\-9] would be used. If the first character
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following the '[' is a '!', any character not enclosed is matched.
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.P
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After device node creation, removal, or network device renaming,
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.B udev
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executes the programs in the directory tree under
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.IR /etc/dev.d/ .
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The name of a program must end with
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.I .dev
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suffix, to be recognized.
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.br
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In addition to the hotplug environment variables,
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.B DEVNAME
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is exported to make the name of the created node, or the name the network
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device is renamed to, available to the executed program. The programs in every
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directory are sorted in lexical order, while the directories are searched in
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the following order:
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.sp
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.nf
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/etc/dev.d/$(DEVNAME)/*.dev
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/etc/dev.d/$(SUBSYSTEM)/*.dev
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/etc/dev.d/default/*.dev
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.fi
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.SH "FILES"
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.nf
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/sbin/udev udev program
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/etc/udev/* udev config files
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/etc/hotplug.d/default/udev.hotplug hotplug symlink to udev program
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/etc/dev.d/* programs invoked by udev
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.fi
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.LP
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.SH "SEE ALSO"
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.BR udevinfo (8),
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.BR udevd (8),
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.BR hotplug (8)
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.PP
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The
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.I http://linux\-hotplug.sourceforge.net/
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web site.
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.SH AUTHORS
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.B udev
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was developed by Greg Kroah-Hartman <greg@kroah.com> with much help from
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Dan Stekloff <dsteklof@us.ibm.com>, Kay Sievers <kay.sievers@vrfy.org>, and
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many others.
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