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 may be used as keys to determine a
-unique name for the device.
+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 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
.B SUBSYSTEM
Match the kernel subsystem name.
.TP
+.B ACTION
+Match the kernel action name.
+.TP
.B DRIVER
Match the kernel driver name.
.TP
should be renamed to.
.TP
.B SYMLINK
-The name of a symlink targeting the node. Multiple symlinks may be
-specified by separating the names by the space character.
-.br
-If both the name and the symlink fields are omitted or its
-values are empty, the device will be ignored and no node will be created.
-.br
-If only the symlink field is given and the name field is omitted,
-the rule will not be applied immediately, but the symlink field is added
-to the symlink list of the rule which will create the node.
-This makes it possible to specify additional symlinks in a possibly
-separate rules file, while the device nodes are maintained by the
-distribution provided rules file.
+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
-will be the last rule applied. No later rules will have any effect.
+stops further rules application. No later rules will have any effect.
.sp
.B ignore_device
-will ignore this device. No node will be created.
+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.
.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
.B %%
The '%' character itself.
.P
-The count of charcters to insert may be limited by specifying
+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
.I .dev
to be recognized.
.br
-In addition to the hotplug environment variables,
+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).
.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.
+.TP
.B UDEV_NO_DEVD
The default behavior of
.B udev
.nf
/sbin/udev udev program
/etc/udev/* udev config files
-/etc/hotplug.d/default/udev.hotplug hotplug symlink to udev program
/etc/dev.d/* programs invoked by udev
.fi
.SH "SEE ALSO"
~ianmdlvl / elogind.git / blobdiff