Now that we have the legalities out of the way, let us now talk about the shell of the Linux operating system. So what is a shell? The shell of an operating system is the screen that you use to interact with the operating system. If you’re thinking about Microsoft Windows, the Windows shell is that graphical user interface where we have the little mouse pointer which we use to go around and click on the various elements of the desktop, such as folders, icons, etc.
The shell is of two types. The first one is the graphical user interface, or GUI. The second one is called the line user interface, or LUI. The LUI basically looks like DOS prompts. So, if you ever played with the Microsoft Windows DOS prompt, the line user interface is exactly that. It is that black and white screen where you type in different commands to get a particular output from the computer.
In Linux, since this is a much more technical operating system preferred by programmers, geeks, engineers, or what have you, they prefer to use the line user interface. So when you go and install Linux, you can either have a graphical component where you can click things in the desktop much like a normal operating system, or you just have that little line user interface.
The main thing that you have to remember about the shell is that the line user interface (LUI) is much more powerful than the graphical user interface (GUI) However, when you install Linux with just a line user interface for the shell, all you are going to get is a prompt. If you don’t know what you need to do with the command prompt, like the various shell commands for that operating system, you will be stuck.
There are many cases where people install Linux with an LUI, but doesn’t know any Linux shell commands for the LUI. So basically, that’s the thing with the Linux line user interface. You are going to have to understand the commands in order to get the computer to do anything that you need it to do.