Fire Up your own Linux Server

Chapter 2. Day-to-day Usage

Unlike Windows, Linux doesn't offer a standard user interface, but provides a number of desktop environments that can be installed on top of the Linux kernel. Fedora Core comes with the KDE and GNOME desktop environments; in this book, we'll be looking primarily at GNOME.

The GNOME Desktop

Most graphical user interfaces are fairly similar; Microsoft Windows, Mac OS, and the GNOME desktop have a lot in common. You likely won't have much trouble finding your way around, but GNOME does do a few things differently. Here's a brief run-down of the GNOME basics to get you up and running.

A Tour of the Desktop

The GNOME desktop, shown in Figure 2.1, displays a bar at the top and a bar at the bottom; in GNOME, these bars are called panels.

Figure 2.1. The GNOME desktop.

The Bottom Panel

The bottom panel offers a clickable button for each window that's open, similar to the Windows Taskbar, as shown in Figure 2.2.

Figure 2.2. The bottom panel of the GNOME desktop.

On the right-hand side of the bottom panel is the workspace switcher, illustrated in Figure 2.3. A workspace (also known as a virtual desktop) is a way to organize your open windows.

Figure 2.3. The workspace switcher displaying in the bottom panel.

As you open windows and move them around, you'll see a little illustration of the window layout appears in the first square. If you then click on the second square, all of the windows will disappear from the screen—the windows are still open, but you can't see them because you've switched to a different workspace. Click on the first square in the workspace switcher, and you'll see that your original windows return.

You can move windows between workspaces by right-clicking on a window's title bar and selecting a workspace from the Move to Another Workspace menu.

By default, you have four workspaces, but you can change this default in the Workspace Switcher Preferences window (right-click on the workspace switcher and select Preferences… to access this).

The Top Panel

The top panel is divided into three sections: the menus and "shortcut" icons are shown on the left, while the notification area appears on the right, as depicted in Figure 2.4.

Figure 2.4. The top panel of the GNOME desktop.

Top Panel Menus

The top panel menus give us access to everything on the computer. The Applications menu shown in Figure 2.5 categorizes all installed applications as Games, Graphics, Internet, Office, and so on. If you installed Firefox, for example, you could find it in the Internet menu

Figure 2.5. Locating Firefox through the Applications menu.

The Places menu depicted in Figure 2.6 lists file locations that may be useful: your home folder, your desktop, drives on the computer, and network locations.

Figure 2.6. The Places menu.

The Desktop menu provides access to configuration—user preferences and system settings—as well as online help, screen locking, log out, and shut down options. These are shown in Figure 2.7.

Figure 2.7. The Desktop menu.

Top Panel Shortcut Icons

The shortcut icons, located in the Launcher Panel next to the menus, provide quick access to common applications.

Figure 2.8. Displaying shortcut icons in the Launcher Panel.

By default, the icons provide shortcuts to the Web browser (Firefox) and the email client (Evolution), as well as the three main OpenOffice.org applications (word processing, spreadsheet, and presentation tool packages) if you have these installed.

Using Windows

The display of windows that comprise the GNOME GUI is similar to the user interface on the Windows platform. Figure 2.9 shows the display of a GNOME window.

Figure 2.9. A GNOME window.

If you've used other operating systems, you're not going to have any trouble with GNOME's windows.

Starting Up and Shutting Down

Because Linux is a true multi-user system, you'll need to log into your system account before you use the system. In GNOME, the default application for handling this task is the GNOME Display Manager (GDM). The GDM login screen will open after all your system's devices and drives have been properly mounted. You'll log in to the system using the account name and password you created after installation.

Keep Out Of root!
It's never advisable to log in to your system as root. Remember that root is the omnipotent account in Linux, and is capable of performing any action on the system. Those actions include deleting system-critical files, which completely disables the system, making it very difficult to recover. root access should always be used sparingly. When logging in to your system, first log in to the user account; then, if necessary, you can perform administrative tasks by switching over to root temporarily.

Remember that it's important to shut down your Linux box gracefully, just as you would a Windows machine. This allows any buffered data to be written to the disk before the system shuts down. You can shut down either by selecting Desktop > Log Out, or through the command line. Let's look first at the graphical tool for shutting down your machine.

Selecting Log Out from the Desktop menu, as shown in Figure 2.10, will give you the options to log out of your system account (returning you to the login screen), to reboot the machine, or to shut down the machine completely.

Figure 2.10. Linux's logout options.

The Linux Filesystem

Drives and Partitions

If you're used to the drive-oriented layout of Windows, the Linux filesystem structure might be a bit confusing. There is no C: drive; in fact, there are no drives as such, only partitions. To muddy the waters a little more, the partitions' actual locations on the hard drive aren't identified clearly. The Linux filesystem is much more abstract than that.

Let me give you an example. My workhorse machine at home, cortex, contains two physical hard drives. One is an old 40GB drive that contains the operating system and all the programs I use. The other is a new, 160GB behemoth I added later, which is partitioned into two sections. The first section contains my personal files: the photos I've taken with my digital camera, my MP3 collection, and few odds and ends. I leave the second section free for temporary files created by my programs.

On a Windows system, these drives would most likely be seen by both the system and the user as C:, D: and E:. Windows would be installed at C:\WINDOWS\, Firefox would live in C:\Program Files\Mozilla Firefox\, my digital photos would reside in a directory called D:\Photos\, and so on. With Windows, the directory name is directly related to the partition, and therefore the hard disk, on which it's stored. This concept is illustrated in Figure 2.11.

Figure 2.11. How C:, D: and E: relate to my physical hard disks.

The Linux filesystem hides this unnecessary detail from you (until, of course, you want to see it). The operating system kernel is stored in a directory called /boot/, Firefox is in /usr/lib/firefox-1.0.4/, my photos and MP3s go into directories called /home/username/photos/ and /home/username/music/, and temporary files go into a directory called /tmp/. There are no obvious signs that these directories reside in different partitions or on different hard disks.

The Linux filesystem assigns each partition a different mount point: a directory through which we access the partition. In our example, the D: in Windows is analogous to /home/tony/ on our Linux system, E: is similar to /tmp/, and C: would be /, the top of the filesystem hierarchy. This structure is depicted in Figure 2.12.

Figure 2.12. The same partitions viewed in Linux.

There's no doubt that it's confusing when you first make the transition from the physical disk-oriented view of Windows to the hierarchical filesystem of Linux. In time, however, you get over the shock and start to see the sense in viewing the system holistically, rather than as separate compartments.

The ext3 Filesystem

Linux is deservedly renowned for its ability to work with many different filesystems. A modern Linux distribution will read, write, and keep track of files in nearly all the Microsoft filesystems—from the original FAT through to NTFS—as well as filesystems used by Mac OS X, OS/2, and all sorts of esoteric operating systems. For Linux, it's a simple matter of loading the appropriate kernel module and mounting a partition. This makes it easy to handle files written on other systems on your Linux machine. In this section, we'll look at the filesystem that's native to your Fedora Core server: ext3.

The ext3 filesystem is an extension of the native Linux filesystem, ext2, and is now the default filesystem for Fedora Core. ext3 extends ext2 with a journaling layer that facilitates quick system recovery, and ensures a high level of data integrity. The journal is constantly updated with notes of file actions that are pending, and those that have been completed.

Journaling protects against data corruption with speed and ease. All pending and completed operations are logged to the journal. The system checks the journal when rebooting, and completes those operations that were pending at the time of a system failure or "dirty shutdown." This protects the consistency of the data that was buffered at the time the system went down.

Recovery time is also decreased by the use of a journaling layer. Rather than checking each file, bit by bit, for consistency, the system merely completes any pending writes noted in the journal. This reduces what was once a 20- to 30-minute reboot operation to mere seconds—an improvement that's especially critical in an enterprise environment.

Filesystems Galore
Other Linux distributions utilize different filesystems. SuSE Linux, for example, uses the ReiserFS filesystem by default. Extensive benchmarking has shown that ReiserFS can more efficiently handle large numbers of small files than can ext3. However, we won't have time to look at these other filesystems. If you'd like more information on the other filesystem options available for your Linux system, you can find a detailed list, descriptions and installation instructions online at Linux Gazette.