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diff --git a/man/udev.xml b/man/udev.xml
index 458d35165..38acdf744 100644
--- a/man/udev.xml
+++ b/man/udev.xml
@@ -30,7 +30,7 @@
udev
- Linux dynamic device management
+ Dynamic device managementDescription
@@ -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.service8, 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
@@ -54,49 +54,27 @@
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 FilesThe 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
and the local administration directory /etc/udev/rules.d.
All rules files are collectively sorted and processed in lexical order,
regardless of the directories in which they live. However, files with
- identical file names replace each other. Files in /etc
+ identical filenames replace each other. Files in /etc
have the highest priority, files in /run take precedence
over files with the same name in /lib. This can be
used to override a system-supplied rules file with a local file if needed;
a symlink in /etc with the same name as a rules file in
/lib, pointing to /dev/null,
- disables the rules file entirely.
-
- Rule files must have the extension .rules; other
- extensions are ignored.
+ disables the rules file entirely. 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.
+ 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 +85,21 @@
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 +107,14 @@
-
+ +=Add the value to a key that holds a list of entries.
-
+ :=Assign a value to a key finally; disallow any later changes.
@@ -148,30 +126,30 @@
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.
-
+
-
+ ACTIONMatch the name of the event action.
-
+ DEVPATHMatch the devpath of the event device.
-
+ KERNELMatch the name of the event device.
-
+ NAMEMatch the name of a network interface. It can be used once the
NAME key has been set in one of the preceding rules.
@@ -179,7 +157,7 @@
-
+ SYMLINKMatch the name of a symlink targeting the node. It can
be used once a SYMLINK key has been set in one of the preceding
@@ -189,20 +167,20 @@
-
+ SUBSYSTEMMatch the subsystem of the event device.
-
+ DRIVERMatch 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.
-
+ ATTR{filename}Match sysfs attribute values of the event device. Trailing
whitespace in the attribute values is ignored unless the specified match
@@ -212,59 +190,59 @@
-
+ KERNELSSearch the devpath upwards for a matching device name.
-
+ SUBSYSTEMSSearch the devpath upwards for a matching device subsystem name.
-
+ DRIVERSSearch the devpath upwards for a matching device driver name.
-
+ ATTRS{filename}Search the devpath upwards for a device with matching sysfs attribute values.
- If multiple matches are specified, all of them
+ If multiple ATTRS 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.
-
+ TAGSSearch the devpath upwards for a device with matching tag.
-
+ ENV{key}Match against a device property value.
-
+ TAGMatch against a device tag.
-
+ TEST{octal mode mask}Test the existence of a file. An octal mode mask can be specified
if needed.
@@ -272,7 +250,7 @@
-
+ PROGRAMExecute a program to determine whether there
is a match; the key is true if the program returns
@@ -280,12 +258,12 @@
executed program in the environment. The program's stdout
is available in the RESULT key.This can only be used for very short-running foreground tasks. For details
- see .
+ see RUN.
-
+ RESULTMatch 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.
@@ -293,63 +271,69 @@
- Most of the fields support shell-style pattern matching. The following
+ Most of the fields support shell glob 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.
+ 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.
+ be used. If the first character following the [ is a
+ !, any characters not enclosed are matched.The following keys can get values assigned:
-
+
-
+ NAMEThe 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.
-
+ SYMLINKThe 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 UTF-8 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.
-
+ OWNER, GROUP, MODEThe permissions for the device node. Every specified value overrides
the compiled-in default value.
@@ -357,7 +341,14 @@
-
+ SECLABEL{module}
+
+ Applies the specified Linux Security Module label to the device node.
+
+
+
+
+ ATTR{key}The value that should be written to a sysfs attribute of the
event device.
@@ -365,16 +356,16 @@
-
+ ENV{key}
- Set a device property value. Property names with a leading '.'
+ 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).
-
+ TAGAttach 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
@@ -387,14 +378,31 @@
-
+ RUN{type}
- 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.
+ Add a program to the list of programs to be executed after processing all the
+ rules for a specific event, 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 program, 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.
@@ -405,43 +413,50 @@
-
+ LABELA named label to which a GOTO may jump.
-
+ GOTOJumps to the next LABEL with a matching name.
-
+ IMPORT{type}Import a set of variables as device properties,
- depending on type:
+ depending on type:
-
+ programExecute 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 .
+ and quoting work like in RUN.
-
+ builtin
+
+ Similar to program, but use one of the
+ built-in programs rather than an external one.
+
+
+
+ fileImport a text file specified as the assigned value, the content
of which must be in environment key format.
-
+ dbImport a single property specified as the assigned value from the
current device database. This works only if the database is already populated
@@ -449,19 +464,19 @@
-
+ cmdlineImport a single property from the kernel command line. For simple flags
- the value of the property is set to '1'.
+ the value of the property is set to 1.
-
+ parentImport 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
+ to import (with the same shell glob pattern matching used for
comparisons).
@@ -472,7 +487,7 @@
-
+ WAIT_FORWait for a file to become available or until a timeout of
10 seconds expires. The path is relative to the sysfs device;
@@ -481,10 +496,10 @@
-
+ OPTIONSRule and device options:
-
+
@@ -511,9 +526,13 @@
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
- started; they can trigger automatic kernel module loading.
+ the specified name. Also, for every tag specified in this rule, create a symlink
+ in the directory
+ /run/udev/static_node-tags/tag
+ pointing at the static device node with the specified name. Static device node
+ creation is performed by systemd-tmpfiles before systemd-udevd is started. The
+ static nodes might not have a corresponding kernel device; they are used to
+ trigger automatic kernel module loading when they are accessed.
@@ -534,14 +553,14 @@
- The , , ,
- , , and
- fields support simple string substitutions. The
+ The NAME, SYMLINK, PROGRAM,
+ OWNER, GROUP, MODE and RUN
+ fields support simple string substitutions. The RUN
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:
-
+ ,
@@ -552,8 +571,8 @@
,
- The kernel number for this device. For example, 'sda3' has
- kernel number of '3'
+ The kernel number for this device. For example,
+ sda3 has kernel number 3.
@@ -621,9 +640,9 @@
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:
+ by specifying the part number as an attribute: %c{N}.
+ If the number is followed by the + character, this part plus all remaining parts
+ of the result string are substituted: %c{N+}.
@@ -674,24 +693,58 @@
- The '%' character itself.
+ The % character itself.
- The '$' character itself.
+ The $ character itself.
-
+
+
+ Hardware Database Files
+ The hwdb files are read from the files located in the
+ system hwdb directory /usr/lib/udev/hwdb.d,
+ the volatile runtime directory /run/udev/hwdb.d
+ and the local administration directory /etc/udev/hwdb.d.
+ All hwdb files are collectively sorted and processed in lexical order,
+ regardless of the directories in which they live. However, files with
+ identical filenames replace each other. Files in /etc
+ have the highest priority, files in /run take precedence
+ over files with the same name in /lib. This can be
+ used to override a system-supplied hwdb file with a local file if needed;
+ a symlink in /etc with the same name as a hwdb file in
+ /lib, pointing to /dev/null,
+ disables the hwdb file entirely. hwdb files must have the extension
+ .hwdb; other extensions are ignored.
+
+ The hwdb file contains data records consisting of matches and
+ associated key-value pairs. Every record in the hwdb starts with one or
+ more match string, specifying a shell glob to compare the database
+ lookup string against. Multiple match lines are specified in additional
+ consecutive lines. Every match line is compared indivdually, they are
+ combined by OR. Every match line must start at the first character of
+ the line.
+
+ The match lines are followed by one or more key-value pair lines, which
+ are recognized by a leading space character. The key name and value are separated
+ by =. An empty line signifies the end
+ of a record. Lines beginning with # are ignored.
+
+ The content of all hwdb files is read by
+ udevadm8
+ and compiled to a binary database located at /etc/udev/hwdb.bin.
+ During runtime only the binary database is used.See Also
- udevd8
+ systemd-udevd.service8,
udevadm8