-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 '!' then any character not enclosed is matched.
+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
+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
+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.