Automatically configure display to detect and use external monitor, if connected.

autoconfigure_display

#!/bin/bash

# Author: Pushpak Dagade

# This script automatically detects if an external monitor is connected,
# and if so, expands my screen with the monitor on the left and my 
# laptop screen on the right. If my laptop lid is shut & an external 
# monitor is connected, this script uses only the external monitor as 
# the display.
#
# TODOS:
# When external monitor is connected, automatically find out its maximum
#  supported resolution and set it. 
# As of now, it is hard coded to be 1600x900

export DISPLAY=:0   ## notify-send involves GUI

#notify-send "testing as user $USER"
xrandr | grep VGA | grep " connected "
if [ $? -eq 0 ]; then
    # External monitor is connected

	# If laptop lid open: Turn on both screens
	# If laptop lid closed: Turn only external monitor screen
	grep -q closed /proc/acpi/button/lid/LID/state
	if [ $? = 0 ]
	then
			# lid is closed
			xrandr --output VGA1 --mode 1600x900 --pos 0x0 --output LVDS1 --off --output HDMI1 --off
			notify-send 'Laptop lid state: Closed' 'Only external monitor turned ON' -i info			
	else
			# lid is open
			xrandr --output VGA1 --mode 1600x900 --pos 0x0 --output LVDS1 --mode 1366x768 --pos 1600x0 --output HDMI1 --off
			notify-send 'Laptop lid state: Open' 'Both screens are now turned ON. \nLEFT :\tExternal Monitor \nRIGHT :\tLaptop Screen' -i info			

	fi    

    if [ $? -ne 0 ]; then
        # Something went wrong. Autoconfigure the internal monitor and disable the external one
        xrandr --output LVDS1 --mode auto --output VGA --off
    fi
else
    # External monitor is not connected
    notify-send 'No external monitor connected' 'Only laptop screen turned ON.' -i info
    xrandr --output LVDS1 --mode 1366x768 --output VGA1 --off --output HDMI1 --off
fi