X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=man%2Fudev.xml;h=eab525f0f35ed265b992d93dba4abd688fd4798b;hp=458d351658d98ad69efc1a29c5b6390866865cb0;hb=6ec0ac43bb1f9f8b8b435ba6e5d55dc7cc84c3c6;hpb=6ada823a9a0979ea145fd70add1007c21caa45c0 diff --git a/man/udev.xml b/man/udev.xml index 458d35165..eab525f0f 100644 --- a/man/udev.xml +++ b/man/udev.xml @@ -41,7 +41,7 @@ names provide a way to reliably identify devices based on their properties or current configuration. - The udev daemon, udevd + The udev daemon, systemd-udevd.service 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 @@ -54,28 +54,7 @@ sources is provided by the library libudev. - Configuration - udev configuration files are placed in /etc/udev - and /usr/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: - - - - - The logging priority. Valid values are the numerical syslog priorities - or their textual representations: , - and . - - - - - - Rules files + Rules files The udev rules are read from the files located in the system rules directory /usr/lib/udev/rules.d, the volatile runtime directory /run/udev/rules.d @@ -94,9 +73,10 @@ 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. + Except for empty lines or lines beginning with '#', which are ignored. + There are two kinds of keys: match and assignment. + If all match keys match against their values, the rule gets applied and the + assignment keys get the specified values assigned. A matching rule may rename a network interface, add symlinks pointing to the device node, or run a specified program as part of @@ -107,21 +87,21 @@ 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. @@ -129,14 +109,14 @@ - + += Add the value to a key that holds a list of entries. - + := Assign a value to a key finally; disallow any later changes. @@ -148,7 +128,7 @@ 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. - + @@ -297,19 +277,19 @@ 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'. @@ -322,12 +302,12 @@ The following keys can get values assigned: - + The name to use for a network interface. The name of a device node - can not be changed by udev, only additional symlinks can be created. + cannot be changed by udev, only additional symlinks can be created. @@ -335,21 +315,26 @@ 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. + this value to the list of symlinks to be created. + The set of characters to name a symlink is limited. Allowed + characters are [0-9A-Za-z#+-.:=@_/], valid utf8 character sequences, + and "\x00" hex encoding. All other characters are replaced by + a '_' character. + 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. + 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 overrides the compiled-in default value. @@ -387,14 +372,31 @@ - + Add a program to the list of programs to be executed for a specific - device. - If no absolute path is given, the program is expected to live in - /usr/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. + device, depending on type: + + + program + + Execute an external program specified as the assigned + value. If no absolute path is given, the program is expected to live in + /usr/lib/udev, otherwise the absolute path must be specified. + This is the default if no type is + specified. + + + + builtin + + As , but use one of the built-in programs rather + than an external one. + + + + The program name and following arguments are separated by spaces. + Single quotes can be used to specify arguments with spaces. This can only be used for very short-running foreground tasks. Running an event process for a long period of time may block all further events for this or a dependent device. @@ -422,10 +424,10 @@ Import a set of variables as device properties, - depending on type: + depending on type: - + program Execute an external program specified as the assigned value and import its output, which must be in environment key @@ -434,14 +436,21 @@ - + builtin + + As , but use one of the built-in programs rather + than an external one. + + + + file Import a text file specified as the assigned value, the content of which must be in environment key format. - + db Import a single property specified as the assigned value from the current device database. This works only if the database is already populated @@ -449,14 +458,14 @@ - + cmdline Import a single property from the kernel command line. For simple flags the value of the property is set to '1'. - + parent Import the stored keys from the parent device by reading the database entry of the parent device. The value assigned to @@ -484,7 +493,7 @@ Rule and device options: - + @@ -512,7 +521,7 @@ Apply the permissions specified in this rule to the static device node with the specified name. Static device node creation can be requested by kernel modules. - These nodes might not have a corresponding kernel device at the time udevd is + These nodes might not have a corresponding kernel device at the time systemd-udevd is started; they can trigger automatic kernel module loading. @@ -541,7 +550,7 @@ 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: - + , @@ -672,26 +681,25 @@ - + %% The '%' character itself. - + $$ The '$' character itself. - See Also - udevd8 + systemd-udevd.service8 , udevadm8