#!/bin/bash
#
#  adjust screen brightness
#
#
# Script to adjust screen brightness
function usage_and_exit {
    echo "Usage: $(basename ${0}) <param1>"
    exit 1
}
# Exit if we have an incorrect number of arguments
if [ ${#} -ne 1 ]; then
    usage_and_exit
fi
BRIGHTNESS=$(( $(</sys/class/backlight/intel_backlight/brightness)+${1} ))
if (( $BRIGHTNESS < 7500 )) && (( $BRIGHTNESS > 0 ))
then
    echo $BRIGHTNESS > "/sys/class/backlight/intel_backlight/brightness"
fi
echo $(( 100*$BRIGHTNESS/7500 ))