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diff --git a/udev.8 b/udev.8 new file mode 100644 index 0000000000..9dae378086 --- /dev/null +++ b/udev.8 @@ -0,0 +1,394 @@ +.TH UDEV 8 "October 2003" "" "Linux Administrator's Manual" +.SH NAME +udev \- Linux configurable dynamic device naming support +.SH SYNOPSIS +.BI udev +.SH "DESCRIPTION" +.B udev +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 +subsystem, +.B udev +is executed if a kernel device is added or removed from the system. +A list of rules is used to match against specific device attributes. +.br +On device addition, +.B udev +matches its configured rules against the available device attributes to +uniquely name the device. +.B udev +maintains its own database for devices present on the system. This database +can be queried for the relationship of the kernel device path and the +name of the device file. +.br +On device removal, +.B udev +queries its database for the name of the device file to be deleted. +.br +After the device node handling, a list of collected programs specific to this +device is executed. +.SH "CONFIGURATION" +All +.B udev +configuration files consist of a set of lines of text. All empty +lines or lines beginning with '#' 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 allowing the user to +override default udev values. The following variables can be overridden +in this file: +.TP +.B udev_root +Indicates where to place the device nodes in the filesystem. The default +value is +.IR @udevdir@/ . +.TP +.B udev_db +The name and location of the udev database. The default value is +.IR @udevdir@/.udevdb . +.TP +.B udev_rules +The name of the udev rules file or directory to look for files with the suffix +.IR .rules . +All rule files are read in lexical order. The default value is +.IR /etc/udev/rules.d/ . +.TP +.B udev_log +The logging priority which can be set to +.IR "err " , "info " +or the corresponding numerical +.BR syslog (3) +value. +The default value is +.IR err . +.P +.RI "A sample " udev.conf " file might look like this: +.sp +.nf +# Where in the filesystem to place the device nodes +udev_root="@udevdir@" + +# The name and location of the udev database. +udev_db="@udevdir@/.udevdb" + +# The name and location of the udev rules file(s). +udev_rules="@configdir@/rules.d" + +# The syslog(3) priority: "err", "info", or the numerical value. +udev_log="err" +.fi +.P +The rules for device naming are read from the files located in the +.I /etc/udev/rules.d/ +directory, or at the location specified by the +.I udev_rules +value in the +.I /etc/udev/udev.conf +file. +.br +Every line in the rules file defines the mapping between device attributes +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 +Every rule consists of a list of comma separated key value fields: +.sp +.IR "key " ,[ "key " ,...] +.P +Each key has the following format: +.sp +.IR "name op value" +.P +There are distinct key operation types, depending on the type of the key, it +does a comparison or an assignment. +.P +Comparison operators are: +.TP +.B == +Compare for equality. +.TP +.B != +Compare for non-equality. +.P +Assignment operators are: +.TP +.B += +Add the value to a key that holds a list of entries. +.TP +.B := +Assign a value to a key finally; disallow any later changes, which +is useful to prevent changes by any later rules. +.TP +.B = +Asign a value to a key. Keys that represent a list, are reset and only this +single value is assigned. While this operator still works inplicitely as +comparison on keys that can't get a value assigned, its usage as an comparison +operator is deprecated. +.P +The following key names can be used to match against device properties: +.TP +.B BUS +Match the bus type of the device. +(The sysfs device bus must be able to be determined by a "device" symlink.) +.TP +.B KERNEL +Match the kernel device name. +.TP +.B SUBSYSTEM +Match the kernel subsystem name. +.TP +.B ACTION +Match the kernel action name. +.TP +.B DRIVER +Match the kernel driver name. +.TP +.B ID +Match the device number on the bus, like PCI bus id. +.TP +.BI SYSFS{ filename } +Match sysfs device attribute like vendor and product id's, USB serial number +or the SCSI disk model number. Up to 5 different sysfs files can be checked, +with 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 +.BI ENV{ variable } +Match an environment variable. Up to 5 different environment variables can be +checked, with all of the values being required to match the rule. +.TP +.B PROGRAM +Call external program. This key is valid if the program returns successful. +The environment variables of +.B udev +are also available to the program. +.br +The string returned by the program may be additionally matched with the +.B RESULT +key in the same or any later rule. +.TP +.B RESULT +Match the returned string of the last +.B PROGRAM +call. This key can be used in the same or in any later rule after a +.B PROGRAM +call. +.P +The following keys can get values assigned: +.TP +.B NAME +The name of the node to be created, or the name, the network interface +should be renamed to. Only one rule can set the a name, all later rules +with a NAME key will be ignored. +.TP +.B SYMLINK +The name of a symlink targeting the node. Every matching rule can add +this value to the list of symlinks to be created along with the device node. +Multiple symlinks may be specified by separating the names by the space +character. +.TP +.B OWNER, GROUP, MODE +The permissions for the device node. Every specified value overwrites the +compiled-in default value. +.TP +.B RUN +Add a program to the list of programs to be executed for a specific device. +.TP +.B OPTIONS +.B last_rule +stops further rules application. No later rules will have any effect. +.sp +.B ignore_device +will ignore this device. No node will be created or program executed. +.sp +.B ignore_remove +will ignore any later remove event for this device. +This may be useful as a workaround for broken device drivers. +.sp +.B all_partitions +will create device nodes for all available partitions of a blockdevice. +This may be useful for removable media devices which do not detect a media +change. +.sp +Multiple attributes may be separated by comma. +.P +.RB "The " NAME ", " SYMLINK ", " PROGRAM ", " OWNER " and " GROUP +fields support simple printf-like string substitutions: +.TP +.B %n +The "kernel number" of the device. +For example, 'sda3' has a "kernel number" of '3'. +.TP +.B %k +The "kernel name" for the device. +.TP +.B %p +The devpath for the device. +.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 string returned by the external program, specified in +.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 +.B %N +The name of a created temporary device node to provide access to the +device from a external program. +.TP +.B %P +The node name of the parent device. +.TP +.BI %s{ filename } +The content of a sysfs attribute. +.TP +.B %r +The udev_root value. +.TP +.B %e +If a device node already exists with the name, the smallest positive +decimal integer N is substituted such that the resulting name doesn't +match an existing device node. Otherwise nothing is substituted. This +can be used to create compatibility symlinks and enumerate devices of +the same type originating from different kernel subsystems. +.sp +Note: The use of the enumeration facility is unreliable outside of +udevstart where the node creation is serialized and predictable. +The returned numbers rely on the order devices are probed on the +system. If more than one device requests an enumeration for the same +name at the same time, it may be possible that both requests receive the +same name back from the database. The use of enumerations in todays setups +where device can come and go at any time is not recomended. +.TP +.B %% +The '%' character itself. +.P +The count of characters 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 " file might look like this:" +.sp +.nf +# if /sbin/scsi_id returns "OEM 0815", the device will be called disk1 +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" + +# 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" + +# USB mouse at third port of the second hub to be called mouse1 +BUS=="usb", ID=="2.3", NAME="mouse1" + +# ttyUSB1 should always be called pda with two additional symlinks +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" +.fi +.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 zero, one, or more characters. +.TP +.B ? +Matches any single character, but does not match zero 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 '!', any characters not enclosed are matched. +.P +After device node creation, removal, or network device renaming, +.B udev +executes the programs specified by the +.B RUN +key. +.br +In addition to the kernel provided hotplug environment variables, +.B UDEV_LOG +is set and contains the numerical priority value, if udev is configured to use +.BR syslog (3). +Executed programs may want to follow that setting. +.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 programs. +.SH "ENVIRONMENT" +.P +The following variables are read from the environment: +.TP +.B ACTION +.IR add " or " remove +signifies the addition or the removal of a device. +.TP +.B DEVPATH +The sysfs devpath of the device without the mountpoint but a leading slash. +.TP +.B SUBSYSTEM +The subsystem the device belongs to. Alternatively the subsystem may +be passed as the first argument. +.TP +.B UDEV_CONFIG_FILE +Overrides the default location of the +.B udev +config file. +.TP +.B UDEV_LOG +Overrides the log priority specified in the config file. +.TP +.B UDEV_RUN +If set to "0", it disables the execution of programs added by rules. +.SH "FILES" +.nf +/sbin/udev udev program +/etc/udev/* udev config files +.fi +.SH "SEE ALSO" +.BR udevinfo (8), +.BR udevd (8), +.PP +.B Web resources: +.nf +.I http://www.kernel.org/pub/linux/utils/kernel/hotplug/udev.html +.I http://linux\-hotplug.sourceforge.net/ +.fi +.SH AUTHORS +.B udev +was developed by Greg Kroah-Hartman <greg@kroah.com> with much help from +Dan Stekloff <dsteklof@us.ibm.com>, Kay Sievers <kay.sievers@vrfy.org>, and +many others. |