How to change the primary monitor in Ubuntu or other Linux distributions

Using dual or multiple monitors in Linux is relatively straightforward as most monitors are automatically detected on the major distributions. However, Gnome does not give an option for specifying which monitor is the primary – that is to say the monitor which holds the panels by default and is considered the ‘default’ display. Fortunately, the xrandr utility can easily switch which monitor is the primary. Copy and paste the following script into a text file called monitor-switcher.sh.