In the world of computers, a shell is a program that serves as an interface between the user and the operating system. There are two types of shells:
- Command-Line Interface(CLI): In this type of shell, the user gives commands by typing text commands in a Terminal.
- Graphical User Interface (GUI): This type of shell presents the user with a graphical interface that includes menus of options. The user generally selects by clicking buttons with minimal text entry as necessary.
In Unix/Linux systems, there are two main CLI-type shells:
- Bourne Again Shell, called Bash
- Z Shell, named Zsh.
Bash is the most common shell in Linux systems. Typing the command echo $SHELL displays the SHELL type.