What is shell program?

• A shell is a program that provides the traditional, text-only user interface for Unix-like operating systems. Its primary function is to read commands that are typed into a console (i.e., an all-text display mode) or terminal window (an all-text window) in a GUI (graphical user interface) and then execute (i.e., run) them. The term shell derives its name from the fact that it is an outer layer of an operating system. A shell is an interface between the user and the internal parts of the operating system (at the very core of which is the kernel).

• You can control and activate all the process in Linux from the shell .login for shell access. There are 7 terminals for Linux. 6 terminals are non - GUI and 1 terminal for GUI access. 

• You can login to each terminal using Alt + Ctrl + F1 , F2, .. F7. Each terminals will request your username and password for login. If you want to use the shell in the graphical interface (GUI), press Alt + F2 and type "konsole". User will have permission to access only your /home/user directory and other directories in it.