#!/bin/bash

if [[ ${#@} == 1 ]]; then
    red=$1
    green=$1
    blue=$1
    brightness=1
else
    red=$1
    green=$2
    blue=$3
    brightness=${4:-1}
fi

declare -a outputs=( $(xrandr --query --current | perl -nle 'm{^(\S+) connected} and print $1' ) )
for o in "${outputs[@]}"; do
    xrandr --output "$o" --gamma "${red}:${green}:${blue}" --brightness "$brightness"
done