Linux is a free and open-source operating system kernel that was created by Linus Torvalds in 1991. It forms the core of many Unix-like operating systems known as Linux distributions.

What is a Linux Shell?

• A Linux shell is a command-line interface (CLI) program that provides a text-based way for users to interact with the Linux-like operating system. It acts as an intermediary between the user and the kernel (the core of the operating system).

Why is the Shell Important?

• The shell allows users to issue commands to the operating system, execute programs, and perform various tasks efficiently.

• It is essential for system administration, automation, and software development on Linux-based systems.

• Many powerful tools and utilities are accessible primarily through the shell.

Different Linux Shells

• There are various Linux shells available, with Bash (Bourne Again Shell) being one of the most common and widely used.

• Other popular shells include Zsh (Z shell) and Fish (Friendly Interactive Shell).

• Each shell has its features and configuration options, but the basic principles are similar.

Before we proceed further, let's clarify some important concepts related to shell and terminal:

1. Terminal:

   • A terminal is a program or application that provides a graphical user interface for interacting with the shell.

   • It's often referred to as a "terminal emulator" because it emulates the behavior of a physical terminal.

   • In a terminal window, you can type commands, view their output, and interact with the shell.

2. Shell:

   • A shell is a command-line interface (CLI) program that interprets and executes commands entered by the user.

   • It's responsible for taking your text-based commands and translating them into actions that the operating system can understand and execute.

   • Shells, such as Bash, Zsh, and Fish, have their own set of features and capabilities.

Now, to open a terminal window on Ubuntu:

• Method 1: Using Keyboard Shortcut

  • You can open a terminal window by pressing Ctrl + Alt + T on your keyboard simultaneously. This keyboard shortcut is the default for most Ubuntu installations.

• Method 2: Using the Application Menu

  • Click on the "Applications" menu in the upper-left corner of your screen (it may look like a grid of dots or the Ubuntu logo).

  • Type "Terminal" in the search bar.

  • Click on the "Terminal" application that appears in the search results.

• Method 3: Using the Run Command

  • Press Alt + F2 to open the "Run a Command" dialog.

  • Type "gnome-terminal" (without quotes) and press Enter. This will open a terminal window.

Once you've opened a terminal window, you'll have access to a shell (typically Bash by default) where you can start entering Linux commands.

Here is what you will see.

Everything before @, is the username, after @ and before : is the computer's name and between : and # is the path of the working directory. The root is the super user (admin) who can things like install, remove, and update apps or operating systems; ...

To enter a command, we type after the # for root user and $ for standards (like you).

A command is a keyword entered in the terminal emulator to perform a specific task, such as creating a file or directory.

e.g: mkdir to create a directory; ls to list the content of a directory; cat print the content of a file.

Thank you for reading.

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