#!/bin/sh
# Brightness control script. It allows easy manual control over screen brightness.

DRIVER="`ls /sys/class/backlight/|head -n 1`"
ACTUAL_BRIGHTNESS=`cat /sys/class/backlight/$DRIVER/actual_brightness`
BRIGHTNESS_FILE="/sys/class/backlight/$DRIVER/brightness"
STEP="10"

case $1 in
'up')
  if [  `expr $ACTUAL_BRIGHTNESS + $STEP` -gt "120" ]
  then
    echo "120" > "$BRIGHTNESS_FILE"
  else
    echo `expr $ACTUAL_BRIGHTNESS + $STEP` > "$BRIGHTNESS_FILE"
  fi

  ;;

'down')
  if [  `expr $ACTUAL_BRIGHTNESS - $STEP` -lt "1" ]
  then
    echo "1" > "$BRIGHTNESS_FILE"
  else
    echo `expr $ACTUAL_BRIGHTNESS - $STEP` > "$BRIGHTNESS_FILE"
  fi

  ;;

'off')
  echo "0" > "$BRIGHTNESS_FILE"

 ;;

*)
    echo "usage: $0 { up | down | off }"

    ;;

esac

exit 0