On UNIX system, from which Linux was derived, the program used to interpret and manage commands are referred to as the shell. The linux shell illustrated in this chapter is called the bash shell. The name is derived from the fact that the bash is compatible with the one of the earliest UNIX shell, the Bourne shell ( named after its creator Stephan Bourne, and represented by sh command).
The following are the few major reasons to learn how to use shell:
1.) You will know how to get around any LINUX or UNIX like systems. You can even log in and run commands on any Android phone. All of them run Linux or similar systems on the inside.
2.) Special shell features enables you to gather data input and direct data output between commands and the Linux file system.
3.) You can gather commands into a file using programming constructs such as conditional tests, loops, and case statements to quickly do complex operations that would be difficult to retype over and over.
ABOUT SHELL AND TERMINAL WINDOWS
There are several ways to get to a shell interface in Linux. Three of the most common are the shell prompt, Terminal window, and virtual console, which you will learn about in the following section.
USING THE SHELL PROMPT
Typing commands from shell will probably be the primary means of using the Linux system.
The default prompt for a regular user is simply a dollar sign:
The default prompt for the root user is a pound sign (also called a hash mark)
In most Linux systems, the $ and # prompts are preceded by your username, system name, and current directory name.