#!/bin/bash

#controls backlight on intel cards,

STEP=50

function usage() {
  echo "usage: "  `basename $0` " [--inc|--dec]"
}

if [ $# -ne 1 ]; then
  usage
  exit 1
fi

MAX=`cat /sys/class/backlight/intel_backlight/max_brightness`
CURRENT=`cat /sys/class/backlight/intel_backlight/brightness`
wanted=$CURRENT

if [ $1 == "--inc" ]; then
        wanted=$(($CURRENT + $STEP))
        if [ $wanted -ge $MAX ]; then
                wanted=$MAX
        fi
elif [ $1 == "--dec" ]; then
        wanted=$(($CURRENT - $STEP))
        if [ $wanted -le 1 ]; then
                wanted=1
        fi
else
  usage
  exit 0
fi

echo $wanted > /sys/class/backlight/intel_backlight/brightness