The Shell

In all version of Unix, the shell is a program that interprets commands and acts as an interface between the user and the kernel.

Multiple shells are available. In Linux systems, the default is the bash shell. MacOS formerly defaulted to bash as well, but has recently switch to zsh.

The shell displays a prompt, which indicates that it is ready to accept commands. In this tutorial, we will utilize the dollar sign $ as the prompt; yours may be different, and later in this tutorial we will learn how to customize it to your preferences.

To determine your current shell, at the prompt type

echo $SHELL

It is important to keep in mind that Unix in general and the shell in particular is case-sensitive. The commands LS and ls would not be the same.