monitor_brightness

#!/usr/bin/python3

import os
import subprocess
import sys
from os import path

bright = "/tmp/external_monitor_brightness.txt"
default_bright = "0.6"
arg1 = None

if len(sys.argv) > 1:
    arg1 = sys.argv[1]

if arg1 is None:
    sys.exit()

# set default value if file doesn't exist yet
if not path.isfile(bright) or os.stat(bright).st_size == 0:
    with open(bright, "w") as f:
        subprocess.run(["xrandr", "--output", "HDMI-A-0", "--brightness", default_bright])
        f.write(default_bright)
        current_bright = float(default_bright)
else:
    with open(bright) as f:
        current_bright = float(f.read())

if arg1 in ["up", "down", "default"]:
    with open(bright, "w") as f:
        if arg1 == "up":
            new_bright = str(round(min(1, current_bright + 0.05), 2))
        elif arg1 == "down":
            new_bright = str(round(max(0.1, current_bright - 0.05), 2))
        elif arg1 == "default":
            new_bright = default_bright

        subprocess.run(["xrandr", "--output", "HDMI-A-0", "--brightness", new_bright])
        f.write(new_bright)