set-resolution.sh

#!/usr/bin/env bash

script_name="${0##*/}"
if [ "$#" -ne 2 ]; then
  echo "Usage: $script_name width height refresh"
  exit 1
fi

width=$1
height=$2
refresh=${3:-60}

if [ "$(xrandr | grep -c "${width}x${height}")" -eq 1 ]; then
  xrandr -s "${width}x${height}"
  exit 0
fi

_cvt=$(cvt "$width" "$height" "$refresh" | tail -1)
mode=${_cvt//Modeline}
name=$(echo "$_cvt" | awk '{ print $2 }' | tr -d '"')
display=$(xrandr | grep -e " connected [^(]" | sed -e "s/\([A-Z0-9]\+\) connected.*/\1/")

# shellcheck disable=SC2116
message="Do you wish to add and change the resolution to ${width}x${height} at ${refresh}hz?$(echo $'\ny/n> ')"
while true; do
  read -rep "$message" yn
    case $yn in
      [Yy]*) 
        xrandr --newmode "$mode"
        xrandr --addmode "$display" "$name"
        xrandr -s "$name"
        exit
        ;;

      [Nn]*) 
        exit
        ;;
    esac
done