X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=udev.8;h=9dae378086ce906d8bdf9c54c525e05449ae8000;hb=420a506ef00b011ddb50249c0c53c07cbc37e04c;hp=1500b3b424d79a5e3f350043a269b154410bda26;hpb=5b8ba50aa27680e14dddde6248f65cc175f933ab;p=elogind.git diff --git a/udev.8 b/udev.8 index 1500b3b42..9dae37808 100644 --- a/udev.8 +++ b/udev.8 @@ -2,174 +2,393 @@ .SH NAME udev \- Linux configurable dynamic device naming support .SH SYNOPSIS -.BI udev " hotplug-subsystem" +.BI udev .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 subsystem, .B udev is executed if a kernel device is added or removed from the system. -On device creation, +A list of rules is used to match against specific device attributes. +.br +On device addition, .B udev -reads the sysfs directory of the given device to collect device attributes -like label, serial number or bus device number. -These attributes are treated as a key -to determine a unique name for device file creation. +matches its configured rules against the available device attributes to +uniquely name the device. .B udev -maintains a database for devices present on the system. +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 the internal database for the name of the device file to be deleted. +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 configuration at -.I /etc/udev/udev.config. -The file consists of a set of lines. All empty lines and -lines beginning with a '#' will be ignored. +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 -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 and the filename for the device. If no matching -configuration is found, the default kernel device name is used. +If no matching rule is found, the default kernel device name is used. .P -The line format is: -.RS +Every rule consists of a list of comma separated key value fields: .sp -.I method, key,[key,...] name +.IR "key " ,[ "key " ,...] +.P +Each key has the following format: .sp -.RE -where valid methods with corresponding keys are: +.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 CALLOUT -calling external program, that returns a string to match -.br -keys: \fBBUS\fP, \fBPROGRAM\fP, \fBID\fP +.B == +Compare for equality. .TP -.B LABEL -device label or serial number, like USB serial number, SCSI UUID or -file system label -.br -keys: \fBBUS\fP, \fIsysfs_attribute\fP +.B != +Compare for non-equality. +.P +Assignment operators are: .TP -.B NUMBER -device number on the bus, like PCI bus id -.br -keys: \fBBUS\fP, \fBID\fP +.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 TOPOLOGY -device position on bus, like physical port of USB device +.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 -keys: \fBBUS\fP, \fBPLACE\fP +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 REPLACE -string replacement of the kernel device name +.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 -key: \fBKERNEL_NAME\fP -.P -The methods are applied in the following order: -.B CALLOUT -, -.B LABEL -, -.B NUMBER -, -.B TOPOLOGY -, -.B REPLACE -.P -The -.B NAME -and -.B PROGRAM -fields support simple printf-like string subtitution: -.RS +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' +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 +The kernel major number for the device. .TP .B %m -the kernel minor number for the device +The kernel minor number for the device. .TP .B %b -the bus id 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.) -.RE +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 -A sample \fIudev.conf\fP might look like this: +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" device will be called disk1 -CALLOUT, BUS="scsi", PROGRAM="/sbin/scsi_id", ID="OEM 0815", NAME="disk1" +# 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 -LABEL, BUS="usb", serial="W09090207101241330", NAME="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 -NUMBER, BUS="pci", ID="00:0b.0", NAME="dsp" +BUS=="pci", ID=="00:0b.0", NAME="dsp" # USB mouse at third port of the second hub to be called mouse1 -TOPOLOGY, BUS="usb", PLACE="2.3", NAME="mouse1" +BUS=="usb", ID=="2.3", NAME="mouse1" -# ttyUSB1 should always be called pda -REPLACE, KERNEL="ttyUSB1", NAME="pda" +# ttyUSB1 should always be called pda with two additional symlinks +KERNEL=="ttyUSB1", NAME="pda", SYMLINK="palmtop handheld" -# USB webcams to be called webcam0, webcam1, ... -LABEL, BUS="usb", model="WebCam Version 3", NAME="webcam%n" +# multiple USB webcams with symlinks to be called webcam0, webcam1, ... +BUS=="usb", SYSFS{model}=="XV3", NAME=="video%n", SYMLINK="webcam%n" .fi .P -Permissions and ownership for the created device files may specified at -.I /etc/udev/udev.permissions. -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. +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 -If +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 -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 +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 -.ft B -.ft /sbin/udev udev program -/etc/udev/* udev config and database files -/etc/hotplug.d/default/udev.hotplug hotplug symlink to udev program +/etc/udev/* udev config files .fi -.LP .SH "SEE ALSO" -.BR hotplug (8) +.BR udevinfo (8), +.BR udevd (8), .PP -The -.I http://linux-hotplug.sourceforge.net/ -web site. +.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 with much help from -Dan Stekloff and many others. +Dan Stekloff , Kay Sievers , and +many others.