The objective is to install KDE plasma desktop as an alternative desktop environment.
We will be using the tasksel command to install KDE plasma desktop. In case the tasksel command is not available on your system you can install it by:
$ sudo apt install tasksel
This is a companion discussion topic for the original entry at https://linuxconfig.org/how-to-install-kde-plasma-desktop-on-ubuntu-18-04-bionic-beaver-linux
NOTE: SOME OF THE POSTS BELOW ARE TRANSFERRED FROM LINUXCONFIG DISQUS COMMENTS.