backlightctl

#!/usr/bin/env bash

# Notify backlight status (0: no, 1: yes) can be overwrite by providing this value as a second argument
arg2=$2
notify=${arg2:-0}

# Get backlight name
name=$(ls /sys/class/backlight/ | awk '{print $1}')
# Get actual brightness
current=$(cat /sys/class/backlight/$name/actual_brightness)
# Get max brightness
max=$(cat /sys/class/backlight/$name/max_brightness)
# Store arg
arg=$1

plus() {
    arg=$(echo $arg | sed "s/+//g")
    value=$(( current + arg ))
    [ $value -gt $max ] && value=$max
    [ $value -lt 1 ] && value=1
    echo $value > /sys/class/backlight/$name/brightness
    msg="$value/$max"
    [ $notify -eq 1 ] && notify-send --urgency=low "💡 Backlight changed" "$msg" && exit
    echo $msg
    exit
}

minus() {
    arg=$(echo $arg | sed "s/-//g")
    value=$(( current - arg ))
    [ $value -gt $max ] && value=$max
    [ $value -lt 1 ] && value=1
    echo $value > /sys/class/backlight/$name/brightness
    msg="$value/$max"
    [ $notify -eq 1 ] && notify-send --urgency=low "💡 Backlight changed" "$msg" && exit
    echo $msg
    exit
}

value() {
    value=$arg
    [ $value -gt $max ] && value=$max
    [ $value -lt 1 ] && value=1
    echo $value > /sys/class/backlight/$name/brightness
    msg="$value/$max"
    [ $notify -eq 1 ] && notify-send --urgency=low "💡 Backlight changed" "$msg" && exit
    echo $msg
    exit
}

[ -z "$(echo $arg | grep "+")" ] || plus
[ -z "$(echo $arg | grep "-")" ] || minus
[ -z "$(echo $arg | grep "[0-9]")" ] || value

exit -1