basic redshift like implimentation with bash

rshift.sh

#!/bin/bash


monitors=$(xrandr --listactivemonitors | tail -n +2 | awk '{print $4}')


# Get the current hour
if [ "$#" -eq 1 ]; then
    current_hour="$1"
else
    current_hour=$(date +%H)
fi

# define what hours we use to decide when to shift
morning=6
evening=20
night=23



# Define the gamma values
gamma_normal="1.0:1.0:1.0"
gamma_red_start="1.0:1.0:1.0"
gamma_red_end="0.95:0.8:0.7"

# Function to interpolate between two values
interpolate() {
    echo "$(awk "BEGIN {print $1 + ($2 - $1) * ($3/6)}")"
}

# Check the time and adjust gamma accordingly
if (( current_hour >= $morning && current_hour < $evening )); then
    for monitor in $monitors; do
        xrandr --output $monitor --gamma $gamma_normal
    done
elif (( current_hour >= $evening && current_hour < $night )); then
    # Calculate how far into the 2PM-8PM period we are, in hours
    hours_into_period=$(( current_hour - $evening ))

    # Interpolate gamma values
    red=$(interpolate $(echo $gamma_red_start | cut -d: -f1) $(echo $gamma_red_end | cut -d: -f1) $hours_into_period)
    green=$(interpolate $(echo $gamma_red_start | cut -d: -f2) $(echo $gamma_red_end | cut -d: -f2) $hours_into_period)
    blue=$(interpolate $(echo $gamma_red_start | cut -d: -f3) $(echo $gamma_red_end | cut -d: -f3) $hours_into_period)

    for monitor in $monitors; do
        xrandr --output $monitor --gamma "$red:$green:$blue"
    done
else
    for monitor in $monitors; do
    xrandr --output $monitor --gamma $gamma_red_end
    done
fi