The word "Linux" refers to an operating system kernel, which in practice is used in a lot of different operating systems. These could be broadly divided between GNU/Linux and various other Linux distributions that do not use GNU operating system components (e.g., Android). The focus here will generally be GNU/Linux-derived OSes. This provides a general overview of some of the commands. It is strongly recommended you refer to your Linux distribution's documentation for details.
Some ways to find basic information about your Linux-based host. Reasonably universal commands below:
Different distributions using the Linux kernel have varying virtualization methods. KVM is the most universal method.