Timelapse script; Usage: `timelapse.sh -d 1 -i 3` to record display 1 (main display) with an interval of 3 seconds OR use `timelapse.sh` and manually select display. An interval of 3 is default.

timelapse.sh

#!/bin/bash

# Check if ffmpeg is installed
if ! command -v ffmpeg &> /dev/null; then
    echo "Error: ffmpeg is not installed or not in the PATH." >&2
    echo "Please install ffmpeg to use this script." >&2
    exit 1
fi

interval=3
display=""

counter=1
datetimestamp=$(date +"%Y%m%d-%Hh%Mm%Ss")
folder=~/Movies/Timelapse/${datetimestamp}
timelapseFilePath="${folder}/timelapse-${datetimestamp}.mp4"

mkdir -p ${folder}

# Function to list displays
list_displays() {
    system_profiler -json SPDisplaysDataType | 
    sed -n '/spdisplays_ndrvs/,/]/p' |
    grep -o '"_name" : "[^"]*"' | 
    sed 's/"_name" : "//;s/"$//' |
    awk '{print NR ") " $0}' > /dev/tty
}

# Function to select a display
select_display() {
    echo "Available displays for recording:" >&2
    list_displays >&2
    echo "" >&2
    read -p "Select a display (enter number): " choice >&2
    echo "$choice"
}

# Parse command-line options
while getopts ":d:i:" opt; do
  case $opt in
    d) display="$OPTARG" ;;
    i) interval="$OPTARG" ;;
    \?) echo "Invalid option -$OPTARG" >&2; exit 1 ;;
    :) echo "Option -$OPTARG requires an argument" >&2; exit 1 ;;
  esac
done

# If no display is set, use interactive selection
if [ -z "$display" ]; then
    display=$(select_display)
fi

generate_video() {
  echo ""
  echo "Generating timelapse video..."
  ffmpeg -loglevel error -framerate 30 -pattern_type glob -i "${folder}/*.png" -vf scale=1920:1080 -c:v libx264 -pix_fmt yuv420p ${timelapseFilePath}
  open ${timelapseFilePath}
}

# Set up the trap to run the generate_video script on exit
trap 'echo ""; generate_video; echo ""; echo "Done."' EXIT

echo ""
echo "Recording goes to ${folder}"
echo "Using display: ${display}"
echo ""
echo "To end recording press ctrl+c"

while true; do
  # Take a fullscreen screenshot and save it to $folder with a sequential name
  screencapture -D${display} -x ${folder}/${counter}.png
  
  # Increment the counter
  ((counter++))
  
  # Wait for the specified interval
  sleep "$interval"
done