#!/bin/bash

if [ $# -eq 1 ];
then
	PAST=`cat /sys/class/backlight/acpi_video0/brightness`
	CURRENT=$PAST

	if [ $1 == "inc" ];
	then
		if [ $CURRENT -lt 10 ];
		then
			((CURRENT++))
		fi
	elif [ $1 == "dec" ];
	then
		if [ $CURRENT -gt 1 ];
		then
			((CURRENT--))
		fi
	elif [ $1 == "get" ];
	then
		echo $PAST
	elif [ $1 -ge 1 ] && [ $1 -le 10 ];
	then
		CURRENT=$1
	fi

	if [ $CURRENT != $PAST ];
	then
		tee /sys/class/backlight/acpi_video0/brightness <<< $CURRENT > /dev/null
	fi
fi