with import <nixpkgs> {};

pkgs.writeShellScriptBin "bright" ''
	#!/bin/sh
	f="/sys/class/backlight/*/brightness"
	if [ "$1" = up ] ; then
		echo $(($(cat $f) + 50)) | sudo tee $f
	fi
	if [ "$1" = down ] ; then
		echo $(($(cat $f) - 50)) | sudo tee $f
	fi
''