Exploring SUSE Linux Enterprise Server

In the first chapter of this book, you learned how to install SUSE Linux Enterprise Server. Assuming that this is your first time on Linux, this chapter will help you get familiar with the Linux operating system. I'll teach you the most essential skills to allow you to manage a SUSE server. Specifically, in this chapter you'll take a tour of the server desktop from a graphical perspective, and you will learn how to work from the GNOME graphical environment that is installed by default. Also, you will learn what default directories are installed on SUSE Linux Enterprise Server. Basically, I'll introduce many topics in this chapter to get you going as fast as possible in the SUSE Linux Enterprise Server desktop. Already know how it is organized? In that case, you can safely skip this chapter.

Logging In

Linux is a multiuser operating system. This means several users are defined on it, and several users can be logged in to it at the same time. So, before you can work on a Linux box, you must tell the system what user account you want to use for logging in. Therefore, the first screen you will see after your server has successfully booted after installation is a graphical login prompt. At this prompt, you will specify who you are, and if you like, you can also choose the graphical environment from which you want to work. In this chapter, I won't make it any more difficult than necessary, so I'll show just how to work with the GNOME environment, which is loaded by default.

Tip Don't like the graphical login? No problem, you can change your server so it will boot with a text interface by default. Check Chapter 10 for more details on how to do that.

Exploring the Linux User Accounts

To log in to your system, you need a valid user account. Although you are the administrator of your server, it is not too sensible to make a habit of logging in with the account of the user root, the administrator for your server. The most important reason for this is to protect you from making mistakes. This is because in most situations your Linux operating system will not ask you whether you are sure you want to perform a certain action. If you give a command and hit the Enter key, your Linux operating system will just do as asked. Linux assumes you know what you're doing. Therefore, to protect yourself, it is a good idea to log in as a regular user and become the administrative user root only if you really need to do so.

Working with Virtual Consoles

After booting your server, you'll see a graphical login screen. But what if something is wrong with your graphical environment and you can't log in from there? In that case, it is nice to know you can work from six virtual consoles as well. These are like physical monitors connected to your server that are hidden under some key sequences. You can open these consoles by pressing the Ctrl+Alt+F1 to F6 keys. (In the nongraphical environment, you would access them with the Alt key only.) From there, you can work from a text-based environment, which can help you if your graphical environment is broken or if you want to experiment while being logged in as another user on your server. You'll learn more about this in Chapter 4.

You can activate the text-based virtual consoles whenever you want. You can do it when you see the graphical login screen, but you can also activate them after you have logged in to the system. If you want to leave the text-based virtual console and return to your graphical environment, you can press Ctrl+Alt+F7.

When you are working with more than one virtual console, it's easy to get confused about the console you are actually using. If this is the case, there are some means to find your way back. The first help is the login prompt you see when activating the virtual console; it will say which console you are working with by means of something like (tty2), as shown in Figure 2-1. Specifically, tty2 means that this is the second terminal (virtual console) attached to your computer. You have activated it with the Ctrl+Alt+F2 key combination.

Welcome to SUSE Linux Enterprise Seruer 10 (ยก506) - Kernel Z.6.16.Zl-0.0-default Ctty4). BTN login:

Figure 2-1. When you activate a virtual console, you see the tty number of the virtual console.

You can also find out which console is active while you are working. Whenever you get confused about your identity, you can open the GNOME terminal from the GNOME menu (click Computer in the lower-left part of the screen) and from there enter the command who am i (basically if you do that, you use the command who followed by the options am and i, which in fact is a clever trick to refer to the option -m for who). This command will always show you the console you are using. Don't confuse who am i with whoami; the latter will just show you your login name and nothing else.

Getting Administrative Access

As I said before, it is good practice not to log in as an administrative user to your server but as a normal user. However, what if you need administrative access to perform some task? In that case, you can use the command su from a text-based console or a GNOME terminal. When you enter the command su, you will be prompted for a password. The server expects you to enter the password of the user root now. Once finished, you are temporarily root, and you can perform any task you like with the privileges of this system administrator account. Done with your work as root? Then you can use exit to return to the environment in which you started.

It might sound cool to become root from a text-based console, but this is not the only way you can work. Another option is to work from the graphical environment. Sometimes when you start a tool that usually needs root access, such as the configuration utility YaST, you will be prompted for root's password, although this works only for programs that have been programmed to do this. Once you have entered the password for user root, you will have root privileges for that program only; in other programs, you will have the permissions only of your regular user account.

One of the characteristics when working with su is that it doesn't overwrite the environment variables of the original user who was logged in before you used su to become root. This could lead to problems, especially when you try to start a graphical program from your su console window in a graphical session. To prevent these problems, on SUSE Linux you can use sux - instead. This command is typical for SUSE and doesn't work on other Linux distributions. If you use sux -, all the environment variables will be set correctly. The result is that this prevents you from getting error messages when you are trying, for example, to start graphical programs from a console window.

If you want to start an administrative program such as the overall SUSE configuration tool YaST, you don't have to think hard how to do that. If you start YaST as a normal user, it will prompt you to enter the root password (see Figure 2-2).

Note Ever heard about KDE? KDE is one of the graphical interfaces you can use on any kind of SUSE Linux. In earlier releases of SUSE Linux Enterprise Server, KDE was the default interface. Since Novell has a lot of knowledge about the GNOME desktop because of its acquisition of Ximian in 2001, SUSE Linux Enterprise Server defaults to the GNOME desktop. If you really want, you can select KDE to be your default desktop environment when performing an installation; however, for the topics discussed in this book, it doesn't really make a difference. The key components to administer SUSE Linux Enterprise Server are YaST and the command line, and these are always the same, no matter what graphical environment you are using. When I'm discussing the graphical desktop in this book, it will be the GNOME desktop environment since it's the default.

Figure 2-2. When you start YaST as a user other than root, you are prompted for the password of the user root.

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