set connected monitor brightness.

brightness.py

#! /usr/bin/env python3
from plumbum import local
import argparse
parser = argparse.ArgumentParser(description='Set all connected monitor brightness.')
parser.add_argument("brightness", type=int, help="brightness percentage")
args = parser.parse_args()

ddcutil = local["/usr/local/bin/ddcutil"]
displays_output = ddcutil["detect"]()

# get all display id's
displays = [int(l.split(" ")[1]) for l in displays_output.split("\n") if l.startswith("Display")]

for i in displays:
    ddcutil["-d"][i]["setvcp"]["10"][args.brightness]()