Networking / Beginners

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Command Shell Basics

A shell is a program that accepts commands from a command prompt and executes them. The shell displays a prompt to let you know it's waiting for a command. When you type the command and press the Enter key, the system reads your command, interprets it, executes it, displays the results, and then displays the prompt again so that you can enter another command.

Getting to a shell

You can work with Linux commands directly from one of the six virtual consoles. If you like the responsiveness of text mode, virtual consoles are for you. To switch to a virtual console, press Ctrl+Alt+Fx. For example, press Ctrl+Alt+F1 to switch to virtual console 1. When you're in a virtual console, you have to answer the logon prompt with a valid username and password. To return to GNOME, press Ctrl+Alt+F7.

The alternative is to work in a terminal window within the GNOME environment. If you have an older computer, you may find that the terminal window is a little unresponsive. If your computer is relatively new, however, the terminal window will be just as responsive as the text-mode virtual console. Plus, you'll have the benefit of a scroll bar that lets you scroll to see text that otherwise would have flown off the screen.

To open a terminal window, choose Applications → System Tools → Terminal. This opens a command shell in a window right on the GNOME desktop. Because this shell runs within the user account GNOME is logged on as, you don't have to log on. You can just start typing commands. When you're done, type Exit to close the window.

For normal Linux users, the command shell prompt character is a dollar sign ($). If you see a hash mark (#) as the prompt character, it means you're logged on as root. Whenever you see a hash prompt, you should be extra careful about what you do because you can easily get yourself into trouble by deleting important files or otherwise corrupting the system.