Untitled

#!/usr/bin/env bash

bl_base=/sys/class/backlight/acpi_video0
cur_br=$(cat $bl_base/brightness)
min_br=0
max_br=$(cat $bl_base/max_brightness)
mid_br=$((($max_br+ $min_br) / 2))
delay=0.01

switch() {
    if [[ $cur_br -eq $1 ]]
    then
        echo $1 > $bl_base/brightness
    elif [[ $cur_br -lt $1 ]]
    then
        for i in $(seq $cur_br $1)
        do
            echo $i > $bl_base/brightness
            sleep $delay
        done
    elif [[ $cur_br -gt $1 ]]
    then
        for i in $(seq $cur_br -1 $1)
        do
            echo $i > $bl_base/brightness
            sleep $delay
        done
    fi
}

case $1 in
    min | mid | max)
        eval "switch \$${1}_br"
        ;;
    *)
        switch $1
        ;;
esac