#!/bin/bash

DIR="/sys/class/backlight"

if [[ -d "$DIR/acpi_video0" ]]; then
   DIR="$DIR/acpi_video0"
elif [[ -d "$DIR/intel_backlight" ]]; then
   DIR="$DIR/intel_backlight"
else
   echo " no backlight "
   echo "n/a"
   exit 33
fi

cat "$DIR/brightness" "$DIR/max_brightness" | gawk '
    NR==1 { cbr = $1 }
    NR==2 { mbr = $1 }
    END {
        printf("%d%\n", cbr / mbr * 100)
        printf("%d\n", cbr / mbr * 100)
        print("\n")
    }
'