X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=udev%2Fudev.xml;h=abbfee7ad13deff359a7fbe157b3f84b708e6572;hp=c740c0d80705c22b9167f80f1fb93a9b9e148264;hb=7df0ed83c113e4744786e7804d398d9d34b43281;hpb=726687ad48bdececed1e7e44387c50e009e28208 diff --git a/udev/udev.xml b/udev/udev.xml index c740c0d80..abbfee7ad 100644 --- a/udev/udev.xml +++ b/udev/udev.xml @@ -1,639 +1,706 @@ - + -
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+ + udev - - - udev - August 2005 - udev - - - - udev - 7 - - - - - udev - dynamic device management - - - DESCRIPTION - udev provides a dynamic device directory containing only the files for - actually present devices. It creates or removes device node files in the - /dev directory, or it renames network interfaces. - - Usually udev runs as udevd - 8 and receives uevents directly from the - kernel if a device is added or removed from the system. - - If udev receives a device event, it matches its configured rules - against the available device attributes provided in sysfs to identify the device. - Rules that match may provide additional device information or specify a device - node name and multiple symlink names and instruct udev to run additional programs - as part of the device event handling. - - - CONFIGURATION - udev configuration files are placed in /etc/udev/ - and /lib/udev/. All empty lines, or lines beginning with - '#' will be ignored. - - Configuration file - udev expects its main configuration file at /etc/udev/udev.conf. - It consists of a set of variables allowing the user to override default udev values. - The following variables can be set: - - - - - Specifies where to place the device nodes in the filesystem. - The default value is /dev. - - - - - - - The logging priority. Valid values are the numerical syslog priorities - or their textual representations: , - and . - - - - - - Rules files - The udev rules are read from the files located in the - default rules directory /lib/udev/rules.d/, - the custom rules directory /etc/udev/rules.d/ - and the temporary rules directory /dev/.udev/rules.d/. - All rule files are sorted and processed in lexical order, regardless - in which of these directories they live. Every line in the rules file contains at least - one key value pair. There are two kind of keys, match and assignment keys. - If all match keys are matching against its value, the rule gets applied and the - assign keys get the specified value assigned. - - A matching rule may specify the name of the device node, add a symlink - pointing to the node, or run a specified program as part of the event handling. - If no matching rule is found, the default device node name is used. - - A rule may consist of a list of one or more key value pairs separated by - a comma. Each key has a distinct operation, depending on the used operator. Valid - operators are: - - - - - Compare for equality. - - - - - - - Compare for non-equality. - - - - - - - Assign a value to a key. Keys that represent a list, are reset - and only this single value is assigned. - - - - - - - Add the value to a key that holds a list of entries. - - - - - - - Assign a value to a key finally; disallow any later changes, - which may be used to prevent changes by any later rules. - - - - - The following key names can be used to match against device properties. - Some of the keys also match against properties of the parent devices in sysfs, - not only the device that has generated the event. If multiple keys that match - a parent device are specified in a single rule, all these keys must match at - one and the same parent device. - - - - - Match the name of the event action. - - - - - - - Match the devpath of the event device. - - - - - - - Match the name of the event device. - - - - - - - Match the name of the node or network interface. It can - be used once the NAME key has been set in one of the preceding - rules. - - - - - - - Match the subsystem of the event device. - - - - - - Match the driver name of the event device. Only set for devices - which are bound to a driver at the time the event is generated. - - - - - - Match sysfs attribute values of the event device. Up to five - keys can be specified per rule. Trailing - whitespace in the attribute values is ignored, if the specified match - value does not contain trailing whitespace itself. Depending on the type - of operator, this key is also used to set the value of a sysfs attribute. - - - - - - - - Search the devpath upwards for a matching device name. - - - - - - - Search the devpath upwards for a matching device subsystem name. - - - - - - - Search the devpath upwards for a matching device driver name. - - - - - - - Search the devpath upwards for a device with matching sysfs attribute values. - Up to five keys can be specified per rule, but all of them - must match on the same device. Trailing whitespace in the attribute values is ignored, - if the specified match value does not contain trailing whitespace itself. - - - - - - - Match against the value of an environment variable. Up to five - keys can be specified per rule. Depending on the type of operator, this key is also used - to export a variable to the environment. - - - - - - - Test the existence of a file. An octal mode mask can be specified - if needed. - - - - - - - Execute external program. The key is true, if the program returns - with exit code zero. The whole event environment is available to the - executed program. The program's output printed to stdout, is available in - the RESULT key. - - - - - - - Match the returned string of the last PROGRAM call. This key can - be used in the same or in any later rule after a PROGRAM call. - - - - - Most of the fields support a shell style pattern matching. The following - pattern characters are supported: - - - - - Matches zero, or any number of characters. - - - - - - Matches any single character. - - - - - - 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. - - - - - The following keys can get values assigned: - - - - - The name of the node to be created, or the name the network interface - should be renamed to. Only one rule can set the node name, all later rules with - a NAME key will be ignored. - - - - - - - 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. - - - - - - - The permissions for the device node. Every specified value overwrites - the compiled-in default value. - - - - - - - The value that should be written to a sysfs attribute of the - event device. Depending on the type of operator, this key is also - used to match against the value of a sysfs attribute. - - - - - - - Export a variable to the environment. Depending on the type of operator, - this key is also to match against an environment variable. - - - - - - - Add a program to the list of programs to be executed for a specific - device. This can only be used for very short running tasks. Running an - event process for a long period of time may block all further events for - this or a dependent device. Long running tasks need to be immediately - detached from the event process itself. - If the specifiefd string starts with - , all current event - values will be passed to the specified socket, as a message in the same - format the kernel sends an uevent. If the first character of the specified path - is an @ character, an abstract namespace socket is used, instead of an existing - socket file. - - - - - - - Named label where a GOTO can jump to. - - - - - - - Jumps to the next LABEL with a matching name - - - - - - - Import a set of variables into the event environment, - depending on type: - - - - - Execute an external program specified as the assigned value and - import its output, which must be in environment key format. - - - - - - Import a text file specified as the assigned value, which must be in - environment key format. - - - - - - Import the stored keys from the parent device by reading - the database entry of the parent device. The value assigned to - is used as a filter of key names - to import (with the same shell-style pattern matching used for - comparisons). - - - - If no option is given, udev will choose between - and based on the executable bit of the file - permissions. - - - - - - - Wait for a file to become available. - - - - - - - Rule and device options: - - - - - Stops further rules application. No later rules will have - any effect. - - - - - - Ignore this event completely. - - - - - - Do not remove the device node when the device goes away. This may be - useful as a workaround for broken device drivers. - - - - - - Specify the priority of the created symlinks. Devices with higher - priorities overwrite existing symlinks of other devices. The default is 0. - - - - - - Create the device nodes for all available partitions of a block device. - This may be useful for removable media devices where media changes are not - detected. - - - - - - Number of seconds an event will wait for operations to finish, before it - will terminate itself. - - - - - - Usually control and other possibly unsafe characters are replaced - in strings used for device naming. The mode of replacement can be specified - with this option. - - - - - - - - The , , , - , , and - fields support simple printf-like string substitutions. The - format chars gets applied after all rules have been processed, right before the program - is executed. It allows the use of the complete environment set by earlier matching - rules. For all other fields, substitutions are applied while the individual rule is - being processed. The available substitutions are: - - - , - - The kernel name for this device. - - - - - , - - The kernel number for this device. For example, 'sda3' has - kernel number of '3' - - - - - , - - The devpath of the device. - - - - - , - - The name of the device matched while searching the devpath upwards for - , , and . - - - - - - - - The driver name of the device matched while searching the devpath upwards for - , , and . - - - - - - , - - The value of a sysfs attribute found at the device, where - all keys of the rule have matched. If the matching device does not have - such an attribute, follow the chain of parent devices and use the value - of the first attribute that matches. - If the attribute is a symlink, the last element of the symlink target is - returned as the value. - - - - - , - - The value of an environment variable. - - - - - , - - The kernel major number for the device. - - - - - , - - The kernel minor number for the device. - - - - - , - - The string returned by the external program requested with PROGRAM. - A single part of the string, separated by a space character may be selected - by specifying the part number as an attribute: . - If the number is followed by the '+' char this part plus all remaining parts - of the result string are substituted: - - - - - , - - The node name of the parent device. - - - - - - - The current name of the device node. If not changed by a rule, it is the - name of the kernel device. - - - - - - - The current list of symlinks, separated by a space character. The value is - only set if an earlier rule assigned a value, or during a remove events. - - - - - , - - The udev_root value. - - - - - , - - The sysfs mount point. - - - - - , - - The name of a created temporary device node to provide access to - the device from a external program before the real node is created. - - - - - - - The '%' character itself. - - - - - - - The '$' character itself. - - - - The count of characters to be substituted may be limited by specifying - the format length value. For example, '%3s{file}' will only - insert the first three characters of the sysfs attribute - - - - AUTHOR - Written by Greg Kroah-Hartman greg@kroah.com and - Kay Sievers kay.sievers@vrfy.org. With much help from - Dan Stekloff and many others. - - - - SEE ALSO - - udevd8 - , - - udevadm8 - - - -
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+ udev + + + + udev + 7 + + + + udev + Linux dynamic device management + + + Description + udev supplies the system software with device events, manages permissions + of device nodes and may create additional symlinks in the /dev + directory, or renames network interfaces. The kernel usually just assigns unpredictable + device names based on the order of discovery. Meaningful symlinks or network device + names provide a way to reliably identify devices based on their properties or + current configuration. + + The udev daemon, udevd + 8, receives device uevents directly from + the kernel whenever a device is added or removed from the system, or it changes its + state. When udev receives a device event, it matches its configured set of rules + against various device attributes to identify the device. Rules that match may + provide additional device information to be stored in the udev database or + to be used to create meaningful symlink names. + + All device information udev processes is stored in the udev database and + sent out to possible event subscribers. Access to all stored data and the event + sources is provided by the library libudev. + + + Configuration + udev configuration files are placed in /etc/udev/ + and /lib/udev/. All empty lines or lines beginning with + '#' are ignored. + + Configuration file + udev expects its main configuration file at /etc/udev/udev.conf. + It consists of a set of variables allowing the user to override default udev values. + The following variables can be set: + + + + + Specifies where to place the device nodes in the filesystem. + The default value is /dev. + + + + + + + The logging priority. Valid values are the numerical syslog priorities + or their textual representations: , + and . + + + + + + Rules files + The udev rules are read from the files located in the + default rules directory /lib/udev/rules.d/, + the custom rules directory /etc/udev/rules.d/ + and the temporary rules directory /run/udev/rules.d/. + All rule files are collectively sorted and processed in lexical order, + regardless of the directories in which they live. However, files in + /etc/udev/rules.d/ take precedence over files with + the same name in /lib/udev/rules.d/; this can be + used to ignore a default rules file if needed. + + Rule files must have the extension .rules; other + extensions are ignored. + + Every line in the rules file contains at least one key-value pair. + There are two kind of keys: match and assignment. + If all match keys are matching against its value, the rule gets applied and the + assignment keys get the specified value assigned. + + A matching rule may rename a network interface, add symlinks + pointing to the device node, or run a specified program as part of + the event handling. + + A rule consists of a comma-separated list of one or more key-value pairs. + Each key has a distinct operation, depending on the used operator. Valid + operators are: + + + + + Compare for equality. + + + + + + + Compare for inequality. + + + + + + + Assign a value to a key. Keys that represent a list are reset + and only this single value is assigned. + + + + + + + Add the value to a key that holds a list of entries. + + + + + + + Assign a value to a key finally; disallow any later changes. + + + + + The following key names can be used to match against device properties. + Some of the keys also match against properties of the parent devices in sysfs, + not only the device that has generated the event. If multiple keys that match + a parent device are specified in a single rule, all these keys must match at + one and the same parent device. + + + + + Match the name of the event action. + + + + + + + Match the devpath of the event device. + + + + + + + Match the name of the event device. + + + + + + + Match the name of the node or network interface. It can + be used once the NAME key has been set in one of the preceding + rules. + + + + + + + Match the name of a symlink targeting the node. It can + be used once a SYMLINK key has been set in one of the preceding + rules. There may be multiple symlinks; only one needs to match. + + + + + + + + Match the subsystem of the event device. + + + + + + Match the driver name of the event device. Only set this key for devices + which are bound to a driver at the time the event is generated. + + + + + + Match sysfs attribute values of the event device. Trailing + whitespace in the attribute values is ignored unless the specified match + value itself contains trailing whitespace. + + + + + + + + Search the devpath upwards for a matching device name. + + + + + + + Search the devpath upwards for a matching device subsystem name. + + + + + + + Search the devpath upwards for a matching device driver name. + + + + + + + Search the devpath upwards for a device with matching sysfs attribute values. + If multiple matches are specified, all of them + must match on the same device. Trailing whitespace in the attribute values is ignored + unless the specified match value itself contains trailing whitespace. + + + + + + + Search the devpath upwards for a device with matching tag. + + + + + + + Match against a device property value. + + + + + + + Match against a device tag. + + + + + + + Test the existence of a file. An octal mode mask can be specified + if needed. + + + + + + + Execute a program to determine whether there + is a match; the key is true if the program returns + successfully. The device properties are made available to the + executed program in the environment. The program's stdout + is available in the RESULT key. + + + + + + + Match the returned string of the last PROGRAM call. This key can + be used in the same or in any later rule after a PROGRAM call. + + + + + Most of the fields support shell-style pattern matching. The following + pattern characters are supported: + + + + + Matches zero or more characters. + + + + + + Matches any single character. + + + + + + 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 via the '-' character. + For example, to match on the range of all digits, the pattern [0-9] could + be used. If the first character following the '[' is a '!', any characters + not enclosed are matched. + + + + + The following keys can get values assigned: + + + + + What a network interface should be named. + Also, as a temporary workaround, this is what a device node + should be named; usually the kernel provides the defined node name or creates + and removes the node before udev even receives any event. Changing + the node name from the kernel's default creates inconsistencies + and is not supported. If the kernel and NAME specify different names, + an error is logged. udev is only expected to handle device node + permissions and to create additional symlinks, not to change + kernel-provided device node names. Instead of renaming a device node, + SYMLINK should be used. However, symlink names must never conflict with + device node names, as that would result in unpredictable behavior. + + + + + + + The name of a symlink targeting the node. Every matching rule adds + this value to the list of symlinks to be created. Multiple symlinks may be + specified by separating the names by the space character. In case multiple + devices claim the same name, the link always points to the device with + the highest link_priority. If the current device goes away, the links are + re-evaluated and the device with the next highest link_priority becomes the owner of + the link. If no link_priority is specified, the order of the devices (and + which one of them owns the link) is undefined. Also, symlink names must + never conflict with the kernel's default device node names, as that would + result in unpredictable behavior. + + + + + + + + The permissions for the device node. Every specified value overwrites + the compiled-in default value. + + + + + + + The value that should be written to a sysfs attribute of the + event device. + + + + + + + Set a device property value. Property names with a leading '.' + are neither stored in the database nor exported to events or + external tools (run by, say, the PROGRAM match key). + + + + + + + Attach a tag to a device. This is used to filter events for users + of libudev's monitor functionality, or to enumerate a group of tagged + devices. The implementation can only work efficiently if only a few + tags are attached to a device. It is only meant to be used in + contexts with specific device filter requirements, and not as a + general-purpose flag. Excessive use might result in inefficient event + handling. + + + + + + + Add a program to the list of programs to be executed for a specific + device. This can only be used for very short running tasks. Running an + event process for a long period of time may block all further events for + this or a dependent device. Long running tasks need to be immediately + detached from the event process itself. + If no absolute path is given, the program is expected to live in + the directory provided at compile-time to configure via --libexecdir + (this is usually /lib/udev), otherwise the absolute + path must be specified. The program name and following arguments are + separated by spaces. Single quotes can be used to specify arguments with + spaces. + + + + + + + A named label to which a GOTO may jump. + + + + + + + Jumps to the next LABEL with a matching name. + + + + + + + Import a set of variables as device properties, + depending on type: + + + + + Execute an external program specified as the assigned value and + import its output, which must be in environment key + format. Path specification, command/argument separation, + and quoting work like in . + + + + + + Import a text file specified as the assigned value, the content + of which must be in environment key format. + + + + + + Import a single property specified as the assigned value from the + current device database. This works only if the database is already populated + by an earlier event. + + + + + + Import a single property from the kernel command line. For simple flags + the value of the property is set to '1'. + + + + + + Import the stored keys from the parent device by reading + the database entry of the parent device. The value assigned to + is used as a filter of key names + to import (with the same shell-style pattern matching used for + comparisons). + + + + If no option is given, udev chooses between + and based on the executable bit of the file + permissions. + + + + + + + Wait for a file to become available or until a timeout of + 10 seconds expires. The path is relative to the sysfs device; + if no path is specified, this waits for an attribute to appear. + + + + + + + Rule and device options: + + + + + Specify the priority of the created symlinks. Devices with higher + priorities overwrite existing symlinks of other devices. The default is 0. + + + + + + Number of seconds an event waits for operations to finish before + giving up and terminating itself. + + + + + + Usually control and other possibly unsafe characters are replaced + in strings used for device naming. The mode of replacement can be specified + with this option. + + + + + + Apply the permissions specified in this rule to the static device node with + the specified name. Static device nodes might be provided by kernel modules + or copied from /lib/udev/devices. These nodes might not have + a corresponding kernel device at the time udevd is started; they can trigger + automatic kernel module loading. + + + + + + Watch the device node with inotify; when the node is closed after being opened for + writing, a change uevent is synthesized. + + + + + + Disable the watching of a device node with inotify. + + + + + + + + The , , , + , , and + fields support simple string substitutions. The + substitutions are performed after all rules have been processed, right before the program + is executed, allowing for the use of device properties set by earlier matching + rules. For all other fields, substitutions are performed while the individual rule is + being processed. The available substitutions are: + + + , + + The kernel name for this device. + + + + + , + + The kernel number for this device. For example, 'sda3' has + kernel number of '3' + + + + + , + + The devpath of the device. + + + + + , + + The name of the device matched while searching the devpath upwards for + , , and . + + + + + + + + The driver name of the device matched while searching the devpath upwards for + , , and . + + + + + + , + + The value of a sysfs attribute found at the device where + all keys of the rule have matched. If the matching device does not have + such an attribute, and a previous KERNELS, SUBSYSTEMS, DRIVERS, or + ATTRS test selected a parent device, then the attribute from that + parent device is used. + If the attribute is a symlink, the last element of the symlink target is + returned as the value. + + + + + , + + A device property value. + + + + + , + + The kernel major number for the device. + + + + + , + + The kernel minor number for the device. + + + + + , + + The string returned by the external program requested with PROGRAM. + A single part of the string, separated by a space character, may be selected + by specifying the part number as an attribute: . + If the number is followed by the '+' character, this part plus all remaining parts + of the result string are substituted: + + + + + , + + The node name of the parent device. + + + + + + + The current name of the device node. If not changed by a rule, it is the + name of the kernel device. + + + + + + + A space-separated list of the current symlinks. The value is + only set during a remove event or if an earlier rule assigned a value. + + + + + , + + The udev_root value. + + + + + , + + The sysfs mount point. + + + + + , + + The name of a temporary device node created to provide access to + the device from a external program before the real node is created. + + + + + + + The '%' character itself. + + + + + + + The '$' character itself. + + + + + + + Author + Written by Greg Kroah-Hartman greg@kroah.com and + Kay Sievers kay.sievers@vrfy.org. With much help from + Dan Stekloff and many others. + + + + See Also + + udevd8 + , + + udevadm8 + + +