#!/bin/sh
# adjust backlight

brightness=$(cat /sys/class/backlight/intel_backlight/brightness)
max_brightness=$(cat /sys/class/backlight/intel_backlight/max_brightness)
step=$((max_brightness/20))

while getopts ud opt; do
	case $opt in
		u)
			case "$brightness" in
				0) echo 1;;
				1) echo "$step";;
				*) echo "$((brightness+step))";;
			esac
		;;
		d) 
			case "$brightness" in
				1) echo 0;;
				"$step") echo 1;;
				*) echo "$((brightness-step))";;
			esac
		;;
		\?) exit 1;;
	esac
done | sudo tee /sys/class/backlight/intel_backlight/brightness > /dev/null