#!/bin/bash
STEP=10
PATH='/sys/devices/platform/applesmc.768/leds/smc::kbd_backlight/brightness'
VALUE=`/bin/cat $PATH`

if [ -n "$1" ]
then
    if [ "$1" == "l" ]
    then
      let VALUE=$VALUE-$STEP
     else
      let VALUE=$VALUE+$STEP
     fi
     echo $VALUE
fi

echo $VALUE > $PATH