#!/bin/bash

backlight=$(ls /sys/class/backlight/)

current=$(cat /sys/class/backlight/$backlight/brightness)
max=$(cat /sys/class/backlight/$backlight/max_brightness)

echo "Brillo actual: $current"

[[ $# -eq 0 ]] && exit 1

_p1=$1
lst="${_p1:${#_p1}-1:1}"

if [[ $lst == 'p' || $lst == '%' ]]; then
    _p1=${_p1#+}
    per="${_p1:0:${#_p1}-1}"
    new=`echo "($current * $per / 100) + $current" | bc`
else
    new=$1
fi

[[ $new -gt $max ]] && { echo "Valor máximo es $max"; exit 1; }


echo -n 'Seteando en '
echo $new | sudo tee "/sys/class/backlight/$backlight/brightness"
logger "Brillo del backlight $backlight establecido a $new"