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Linux Basics

In this chapter from Sams Teach Yourself Red Hat Linux in 24 Hours, you'll learn some of the most basic knowledge you’ll need to get around your new Linux system.

Now that you've installed Red Hat Linux, you might wonder what to do next. Whether you're the kind of person who learns by jumping right in and starting to play or if you prefer to have some structure when exploring a new subject, after this hour you will have some of the most basic knowledge you need to get around your new Linux system. This chapter assumes no knowledge of Linux, so if you are already familiar with Linux or UNIX, feel free to go on to Hour 4, "Exploring the Red Hat Linux Filesystem."

In this hour you will

  • Make a paradigm shift into the Linux way of thinking

  • Learn what happens when you start Linux

  • Log in to Linux using runlevel 3 or runlevel 5, and learn why you should not log in as root to do ordinary work

  • Study the structure of the Unix command and learn some of the most basic Unix commands

  • Get help with the man and info pages

  • Shut down Linux properly

Most topics explored this hour pertain to all flavors of Unix-like operating systems, including Linux and BSD. When that is the case we refer to the system as "Unix" (Title case), to encompass all flavors of *nix.

The Paradigm Shift

Many people are scared away from Linux because they think it's difficult to use. Linux is only difficult if you don't understand that with Linux comes power and freedom. You have more power to do things the way you want to, and you have more freedom to do tasks in different ways. With power and freedom comes responsibility to learn a little bit more about the reasons why you do things. In the end, a whole universe can open up to you, and using your computer will be a lot more fun and hassle-free than when you were forced to use only Windows.

When you use Linux, you communicate with your computer in a different way from when you use Windows or Macintosh. In Windows, 99% or more of the commands you give and the messages you receive are done via graphical user interface, or GUI. You point on a button with your mouse, click it, and something happens. It is possible to open an MS-DOS prompt and give commands the good old-fashioned way in DOS, but you are strictly limited in what you can accomplish. For almost every task in Windows, you must use the graphical interface.

In Linux, this simply is not the case. There is a graphical user interface in Linux called X, and it looks a lot like Windows. You point your mouse to a button or menu item and click to give a command. An example of X running the GNOME desktop environment is shown in Figure 3.1.

The difference with Linux is that for every task you perform with a mouse within X, there is a direct and usually more powerful way to do the same task by typing a command on the keyboard. When you type a command on the keyboard, you are usually in a shell environment (or shell, for short), and the place where you type the command is called the command line. The shell environment is pictured in Figure 3.2.

Figure 3.1
The X interface works on top of the operating system. It is not integrated into the operating system, like the interface is in Windows.

Figure 3.2
Don't be afraid of the shell! It doesn't look as friendly as X, but it's not hard to learn.

You can use Linux quite successfully without ever using the shell, but it is difficult, if not impossible, to advance beyond basic proficiency if you only use the graphical interface. To explore the true power of Linux, you must know how to use the command line. For this reason, we will start our exploration of Linux in a shell, as if X didn't even exist.

If this prospect makes you a bit nervous, maybe this analogy will help. Imagine that you are carrying on a conversation with a friend, but the only way you can communicate is by holding up little pictures to each other. Your conversation would be quite limited, wouldn't it? Now imagine that you and your friend were having a conversation using spoken language (or sign language!). Think of how much more you can communicate with words than with a limited set of pictures. This analogy is kind of rough, but giving commands to your Linux computer using the command line is much like carrying on a conversation. There are different words you can use to communicate the same command, and there are different options you can attach to your command that mean different things, much like the tone and inflection of your voice communicates different ideas when you say the same word.

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