set_primary_display.sh -- a bash script to set your primary display inside a Linux desktop environment using the terminal

set_primary_display.sh

#!/bin/bash

# print a terminal-wide horizontal line with '-' characters
function hr_prn(){
printf '%*s\n' "${COLUMNS:-$(tput cols)}" '' | tr ' ' -
}

# Get the list of connected displays and their resolutions
DISPLAYS=($(xrandr | grep " connected" | awk '{print $1}'))
CURRENT_PRIMARY=$(xrandr --query | grep " connected primary" | awk '{print $1}')

# Get the list of resolutions for each display
for i in ${!DISPLAYS[@]}; do
    RESOLUTIONS[$i]=$(xrandr | grep "${DISPLAYS[$i]}" | awk '{print $4}')
done

# Print the list of displays and their current status
hr_prn &&
echo "::: Available displays:" &&
hr_prn &&
for i in ${!DISPLAYS[@]}; do
    if [[ ${DISPLAYS[$i]} == $CURRENT_PRIMARY ]]; then
        echo "$i. ${DISPLAYS[$i]} (${RESOLUTIONS[$i]}) *"
    else
        echo "$i. ${DISPLAYS[$i]} ${RESOLUTIONS[$i]})"
    fi
done

# If command line argument is given, use that as choice
if [[ $# -eq 1 ]]; then
    CHOICE=$1
else
    # Ask the user to choose a display to set as the primary display
    hr_prn &&
    echo "::: [* = Current main display]"
    hr_prn &&
    read -p "Enter the number of the display to set as primary: " CHOICE
fi

# Check if the display number exists
if [[ $CHOICE -ge 0 && $CHOICE -lt ${#DISPLAYS[@]} ]]; then
    # Check if the display is already the main display
    if [[ ${DISPLAYS[$CHOICE]} == $CURRENT_PRIMARY ]]; then
        hr_prn &&
        echo "::: [ERROR!] Display ${DISPLAYS[$CHOICE]} is already the primary display!" &&
        hr_prn
    else
        # Set the chosen display as the primary display
        xrandr --output ${DISPLAYS[$CHOICE]} --primary
        hr_prn &&
        echo "::: Display ${DISPLAYS[$CHOICE]} set as primary display." &&
	hr_prn
    fi
else
    hr_prn &&
    echo "::: [ERROR!] Invalid display number. Please choose a valid number from the list."
fi