181 lines
4.5 KiB
Groff
181 lines
4.5 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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.SH "DESCRIPTION"
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.B udev
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creates or removes device node files usually located in the /dev directory.
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Its goal is to provide a dynamic device directory that contains only the files
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for devices that are actually present.
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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 are treated as a key
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to determine a unique name for device file creation.
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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 the internal database for the name of the device file to be deleted.
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.SH "CONFIGURATION"
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.B udev
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expects its configuration at
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.I /etc/udev/udev.config.
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The file consists of a set of lines. All empty lines and
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lines beginning with a '#' will be ignored.
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.br
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Every line defines the mapping between device attributes and the device file
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name. It starts with a keyword defining the method used to match, followed by
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one ore more keys to compare and the filename for the device. If no matching
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configuration is found, the default kernel device name is used.
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.P
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The line format is:
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.RS
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.sp
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.I method, key,[key,...] name
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.sp
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.RE
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where valid methods with corresponding keys are:
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.TP
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.B CALLOUT
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calling external program, that returns a string to match
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.br
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keys: \fBBUS\fP, \fBPROGRAM\fP, \fBID\fP
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.TP
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.B LABEL
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device label or serial number, like USB serial number, SCSI UUID or
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file system label
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.br
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keys: \fBBUS\fP, \fIsysfs_attribute\fP
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.TP
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.B NUMBER
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device number on the bus, like PCI bus id
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.br
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keys: \fBBUS\fP, \fBID\fP
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.TP
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.B TOPOLOGY
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device position on bus, like physical port of USB device
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.br
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keys: \fBBUS\fP, \fBPLACE\fP
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.TP
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.B REPLACE
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string replacement of the kernel device name
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.br
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key: \fBKERNEL_NAME\fP
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.P
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The methods are applied in the following order:
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.B CALLOUT
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,
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.B LABEL
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,
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.B NUMBER
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,
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.B TOPOLOGY
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,
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.B REPLACE
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.P
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The
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.B NAME
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and
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.B PROGRAM
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fields support simple printf-like string subtitution:
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.RS
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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 %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 CALLOUT program returned string
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(this does not work within the PROGRAM field for the obvious reason.)
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.TP
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.B %D
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Use the devfs style disk name for this device.
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For partitions, this will result in 'part%n'
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If this is not a partition, it will result in 'disk'
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.RE
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.P
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A sample \fIudev.conf\fP 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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CALLOUT, BUS="scsi", PROGRAM="/sbin/scsi_id", ID="OEM 0815", NAME="disk1"
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# USB printer to be called lp_color
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LABEL, BUS="usb", serial="W09090207101241330", NAME="lp_color"
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# sound card with PCI bus id 00:0b.0 to be called dsp
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NUMBER, 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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TOPOLOGY, BUS="usb", PLACE="2.3", NAME="mouse1"
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# ttyUSB1 should always be called pda
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REPLACE, KERNEL="ttyUSB1", NAME="pda"
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# USB webcams to be called webcam0, webcam1, ...
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LABEL, BUS="usb", model="WebCam Version 3", NAME="webcam%n"
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.fi
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.P
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Permissions and ownership for the created device files may specified at
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.I /etc/udev/udev.permissions.
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The file consists of a set of lines. All empty lines and
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lines beginning with a '#' will be ignored.
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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 end with a
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wildcard to apply the values to a whole class of devices.
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.br
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If
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.B udev
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was built using klibc or is used before the user database is accessible (e.g.
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.B initrd
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), only numeric owner and group values may be used.
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.sp
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A sample \fIudev.permissions\fP 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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.SH "FILES"
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.nf
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.ft B
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.ft
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/sbin/udev udev program
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/etc/udev/* udev config and database files
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/etc/hotplug.d/default/udev.hotplug hotplug symlink to udev program
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.fi
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.LP
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.SH "SEE ALSO"
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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> and many others.
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