control laptop backlight via xbacklight and send notification via libnotify

backlight.sh

#!/bin/bash

# You can call this script like this:
# $./backlight.sh up
# $./backlight.sh down

function get_brightness {
    cat /sys/class/backlight/intel_backlight/brightness;
}

function max_brightness {
    cat /sys/class/backlight/intel_backlight/max_brightness;
}

function send_notification {
    brightness=`get_brightness`
    max_brightness=`max_brightness`
    percent=$(echo "scale=2; ($brightness / $max_brightness)*100" | bc)
    percent=${percent%.*}
    echo $percent
    # Make the bar with the special character ─ (it's not dash -)
    # https://en.wikipedia.org/wiki/Box-drawing_character
    bar=$(seq -s "─" $(($percent / 5)) | sed 's/[0-9]//g')
    # Send the notification
    notify-send "$percent% $bar" -t 5000 -r 1001
}

case $1 in
    up)
	xbacklight -inc 2
	send_notification
	;;
    down)
	xbacklight -dec 2
	send_notification
	;;
esac