XQuartz is an open-source version of X.Org X Window System that runs on macOS, it is required to run certain cross-platform applications on macOS. XQuartx was included with Mac OSX 10.5 (Leopard) to Mac OSX 10.7 (Lion), for all subsequent releases XQuartz is not included and must be downloaded separately.
1.Download the latest version of XQuartz from https://www.xquartz.org
2.Navigate to the downloads folder and open the XQuartz Disk Image (XQuartz-2.7.11.dmg)
3.Open the the XQuartz package (XQuartz.pkg)
4.Follow the installation steps, accepting the licence agreement and choose an installation destination.
5.Once installation is complete logout and log in.
6.Open the Terminal App
7.Login to Viper ssh -Y <username>@viper.hull.ac.uk
[username@login01 ~]$ ssh -Y <username>@viper.hull.ac.uk
|Note: -Y is used to enable the X window system..|
To test X11 support type xclock, an analogue clock should appear.
[username@login01 ~]$ xclock