#!/bin/bash

case "$1" in
    increase)
        CURRENT=`cat /sys/class/backlight/intel_backlight/brightness`
        ((FOO=CURRENT+500))
        exec echo $FOO | tee /sys/class/backlight/intel_backlight/brightness
        ;;
    decrease)
        CURRENT=`cat /sys/class/backlight/intel_backlight/brightness`
        ((FOO=CURRENT-500))
        exec echo $FOO | tee /sys/class/backlight/intel_backlight/brightness
        ;;
esac
exit 0