How to change hostname on Ubuntu 18.04

This tutorial will guide you through the process of changing a hostname on a Ubuntu 18.04 system. The hostname is set at the time when the Ubuntu operating system is installed or if you are spinning up a virtual machine it is dynamically assigned to the instance at startup. The method described in this tutorial will work without the need of restarting your system. Although this tutorial is written for Ubuntu 18.04 Bionic Beaver the same steps can be used for Ubuntu 16.04 Xenial Xerus.