X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=udev.8;h=fd1b6dd2285e583c75ad1deb6e7fa038aeeeb01f;hp=efb02cc6189b7493b802556fcd47a0c44190f3cf;hb=72ffa78debb1f96488b5e13d3151486563b460e7;hpb=3370fb2152d5c812ed4a48b9108a97b446713c9d diff --git a/udev.8 b/udev.8 index efb02cc61..fd1b6dd22 100644 --- a/udev.8 +++ b/udev.8 @@ -2,40 +2,111 @@ .SH NAME udev \- Linux configurable dynamic device naming support .SH SYNOPSIS -.B udev +.BI udev " hotplug-subsystem" .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 are treated as a key +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. +queries the internal database for the name of the device file to be deleted. +.SH "CONFIGURATION" +All udev configuration files consist of a set of lines of text. All empty +lines, and lines beginning with a '#' will be ignored. .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. + +.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 udev_root +This is the where in the filesystem to place the device nodes. The default +value for this is +.I /udev/ +.TP +.B udev_db +The name and location of the udev database. The default value for this is +.I /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 +.TP +.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 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 -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. .P -.I method, key,[key,...] [owner,] [group,] [mode,] name +A sample \fIudev.conf\fP 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 define 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 and the filename for the +device. If no matching configuration is found, the default kernel device name +is used. +.P +The line format is: +.RS +.sp +.I method, key,[key,...] name +.sp +.RE +where valid methods with corresponding keys are: +.TP +.B CALLOUT +calling external program, that returns a string to match +.br +keys: \fBBUS\fP, \fBPROGRAM\fP, \fBID\fP .TP .B LABEL device label or serial number, like USB serial number, SCSI UUID or @@ -57,13 +128,54 @@ keys: \fBBUS\fP, \fBPLACE\fP string replacement of the kernel device name .br key: \fBKERNEL_NAME\fP -.TP +.P +The methods are applied in the following order: .B CALLOUT -calling external program, that returns a string to match -.br -keys: \fBBUS\fP, \fBPROGRAM\fP, \fBID\fP -.SH "EXAMPLE" +, +.B LABEL +, +.B NUMBER +, +.B TOPOLOGY +, +.B REPLACE +.P +The +.B NAME +and +.B PROGRAM +fields support simple printf-like string subtitution: +.RS +.TP +.B %n +the "kernel number" of the device +for example, 'sda3' has a "kernel number" of '3' +.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 CALLOUT program returned string +(this does not work within the 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 'disk' +.RE +.P +A sample \fIudev.rules\fP might look like this: +.sp .nf +# if /sbin/scsi_id returns "OEM 0815" device will be called disk1 +CALLOUT, BUS="scsi", PROGRAM="/sbin/scsi_id", ID="OEM 0815", NAME="disk1" + # USB printer to be called lp_color LABEL, BUS="usb", serial="W09090207101241330", NAME="lp_color" @@ -76,24 +188,55 @@ TOPOLOGY, BUS="usb", PLACE="2.3", NAME="mouse1" # ttyUSB1 should always be called pda REPLACE, KERNEL="ttyUSB1", NAME="pda" -# if /sbin/dev_id returns "V0815" device will be called dev0815 -CALLOUT, PROGRAM="/sbin/dev_id", BUS="pci", ID="V0815", NAME="dev0815" +# USB webcams to be called webcam0, webcam1, ... +LABEL, BUS="usb", model="WebCam Version 3", NAME="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. +The file consists of a set of lines. All empty lines and +lines beginning with a '#' will be ignored. +.br +Every line lists a device name followed by owner, group and permission +mode. All values are separated by colons. The name field may end with a +wildcard 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. +.B initrd +), only numeric owner and group values may be used. +.sp +A sample \fIudev.permissions\fP 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 .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 with much help from +.B udev +was developed by Greg Kroah-Hartman with much help from Dan Stekloff and many others.