Just to add on to this answer, udev also lets you pass arguments to RUN and PROGRAM.
From the udev man page:
The NAME, SYMLINK, PROGRAM, OWNER, GROUP, MODE and RUN fields support simple
printf-like string substitutions. The RUN format chars gets applied after
all rules have been processed, right before the program is executed. It
allows the use of device properties set by earlier matching rules. For all
other fields, substitutions are applied while the individual rule is being
processed.
For example, you could have a rule like this:
# Passes major, minor and serial number as parameters to script.
ACTION=="add", SUBSYSTEM=="usb", RUN+="/tmp/test.sh %M %m $attr{serial}"
The available substitutions are:
$kernel, %k
The kernel name for this device.
$number, %n
The kernel number for this device. For example, ´sda3´ has kernel number
of ´3´
$devpath, %p
The devpath of the device.
$id, %b
The name of the device matched while searching the devpath upwards for
SUBSYSTEMS, KERNELS, DRIVERS and ATTRS.
$driver
The driver name of the device matched while searching the devpath
upwards for SUBSYSTEMS, KERNELS, DRIVERS and ATTRS.
$attr{file}, %s{file}
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.
$env{key}, %E{key}
A device property value.
$major, %M
The kernel major number for the device.
$minor, %m
The kernel minor number for the device.
$result, %c
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: %c{N}. If
the number is followed by the ´+´ char this part plus all remaining
parts of the result string are substituted: %c{N+}
$parent, %P
The node name of the parent device.
$name
The current name of the device node. If not changed by a rule, it
is the name of the kernel device.
$links
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.
$root, %r
The udev_root value.
$sys, %S
The sysfs mount point.
$tempnode, %N
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.
