Auto adjust brightness with remaining battery

batteryBrightness.sh

#! /bin/bash

while true
do
    chargingState=$(grep "charging state:" /proc/acpi/battery/BAT0/state | awk '{print $3}')
    batteryFull=$(grep "design capacity:" /proc/acpi/battery/BAT0/info | awk '{print $3}')
    batteryRemaining=$(grep "remaining capacity:" /proc/acpi/battery/BAT0/state | awk '{print $3}')

    batteryPercentage=$((batteryRemaining * 100/batteryFull))

    if [ $chargingState == "discharging" ] 
    then
        if ((batteryPercentage > 30))
        then
            xbacklight -set $batteryPercentage
        else
            xbacklight -set 0
        fi
    fi

    sleep 60
done