gistfile1.txt

#!/bin/bash
# /usr/local/bin/brightness
# wrapper script to change brightness values
# make script executable

# constants - edit as required
UPPER=4882
LOWER=1
INCREMENT=100
DECREMENT=100

# current value
CURRENT=`cat /sys/class/backlight/intel_backlight/brightness`
NEW=$CURRENT

#if [ $CURRENT -eq 0 ]; then
#	CURRENT=1;
#fi


case $1 in
	up)
		if [ $(($CURRENTi+$INCREMENT)) -le $UPPER ]; then
			NEW=$(($CURRENT+$INCREMENT))
		fi
	;;
	down)
		if [ $(($CURRENT - $DECREMENT)) -ge $LOWER ]; then
			NEW=$(($CURRENT - $DECREMENT))
		fi
	;;
	*)
	;;
esac

# set the new brightness value 
echo $NEW > /sys/class/backlight/intel_backlight/brightness

exit 0