#!/bin/bash

operation="${1}"

case "$operation" in
  up)
#    brightnessctl set +5% | sed -En 's/.*\(([0-9]+)%\).*/\1/p'
    brighness_change="+5%"
    ;;&
  down)
#    brightnessctl set 5%- | sed -En 's/.*\(([0-9]+)%\).*/\1/p'
    brighness_change="5%-"
    ;;&
  up|down)
    brightnessctl set "${brighness_change}"
    ;;
esac