In Appendix A, we said that JDS is based on Linux, which provides key system functions such as handling users, files, memory, and networking. We also mentioned that the desktop (the graphical user interface) was GNOME, heavily customized by Sun Microsystems to provide its own branded look. GNOME, in turn, is built on more basic GUI functions provided by the X Window System.

Separating critical system functions from the desktop is not unusual. Mac OS X offers a GUI called Aqua and an underlying operating system called Darwin that is very similar to Linux. Microsoft Windows used to have the same structure: the graphical interface was layered on top of an operating system called MS-DOS. While Microsoft gradually brought all the functions into an integrated graphical operating system, it still provides a command-line interface, known as the MS-DOS prompt.

Some reasons for the separation of desktop and underlying functions is historical. Operating systems were accessible at first only to batch jobs written in programming languages. Then command-line interfaces were added. Desktops came even later.

But there are other reasons for the separation. One is to facilitate the development of new and better desktops. Another is to allow access by the command line, which is a very powerful and efficient interface for advanced users. (Users with even more training can write scripts or programs that manipulate the operating system functions very efficiently.)

The Nautilus file manager works a lot like a web browser. But Nautilus lets you see your operating system and other computers on your network, while your web browser finds web pages.

Nautilus makes it easy to manage files and the rest of your system. Figure 3-1 presents an example of a window displayed by Nautilus.

Figure 3-1. The Nautilus browser

Files reside on your hard drive or on the drive of a remote system you have rights to.Think of your computer and operating system as a downtown office building and think of Nautilus as an elevator with a full view of each floor. With the elevator’s monitor, you can see thumbnails of everything on each floor as you reach it and therefore everything in the building.

For example, if you work in a forty-story office building, your company may be on the twentieth floor, and your office may be in suite 2050. Your desk sits in corridor D, in the third cubicle from door 2 on the right. Your project files reside in your lower-righthand desk drawer, in alphabetical order. This is an example of a hierarchy, an inverted tree structure describing everything in the building.

Now think of the JDS files and folders as your office building. The contractors created a hierarchical addressing scheme, with the penthouse at the top. The penthouse is the root of the tree, represented by / (a slash). Figure 2-21 in Chapter 2 showed a part of the hierarchy.

On several of the floors of your office building, activities occur which do not require your attention. You do not need to know much about the shipping docks, maintenance areas, security, air-conditioning, etc. Even on your company’s floor, you may not need to know what goes on in the executive offices, in recruiting, or in the conference rooms. And you may not be given access to these areas.

Similarly, with JDS, you know that other things occur in the operating system that don’t concern you. You probably do not need to know the hard drive locations of the files that connect you to the Internet. But Nautilus is there to take you throughout the hierarchy where you do want to go, if you have access rights (permissions).

To explore Nautilus, double-click on the icon called Documents on your desktop. A window opens and you can see the contents of this folder. It may be empty if you have not yet used StarOffice to create any documents. In that case, you can find another folder that has something in it. Click your mouse in the Location box, erase the word Documents, and press the Enter key. Nautilus will display your home directory with all its contents.

The window contains icons that represent the files and folders under the current location. For example, if you created a folder called work and saved a file in it, you can find the file by clicking on the work icon. You can then click on the icon for the file, and JDS opens it, using an application that it chooses based on the filename’s suffix.

The Nautilus file manager helps you:

Let’s add something to your open Documents folder. Select File → New Folder from the drop-down menu at the top. You see a folder icon with the text “untitled folder” beneath it. Type My Novel and press Enter. You have a subfolder under the Documents folder, in which you can save files from the StarOffice tools described in Chapter 7 and Chapter 8, or from other applications.

If you don’t actually want to write a novel, right-click on the folder you just created and choose the "Move to Trash” option from the resulting menu. The folder disappears, but JDS keeps it around in case you change your mind.

Select Go → Trash from the drop-down menu, and your missing folder appears. To get rid of this folder permanently and free up the disk space it uses, right-click on it and select “Delete from Trash” from the menu that appears.

Nautilus also has the hidden task of managing the files that control how your desktop looks and feels. You shouldn’t have to deal with these files. They simply record what you do through JDS’s graphical interface.

Icons of various types let you know what the items are in Nautilus and on the desktop. Some of the icons you encounter on a regular basis are shown in Table 3-1.

Table 3-1. Common icons

Icon	Represents
	A folder icon, representing a Linux directory. Each folder can contain files and other folders. Double-click on a folder to see the contents.
	Indicates you chose the Information button. When you press that button, this icon appears on the side pane of your file browser.
	An associated file, meaning that the file identified by this icon has an application associated with it. When you click on the icon, the application is invoked to open the file. In this case, the file has an .sxw extension and can be opened by StarOffice Writer.
	Another associated file. In this case, the file has a .doc extension. It can also be opened by StarOffice Writer.
	A nonassociated file. The system does not know which application to use to open this file.
	A spin box, which lets you increase or decrease a numerical value by typing in a new value or by clicking on the arrows at the right.

Some icons reveal the contents of the files with which they are associated. For instance, if you store a photograph in a JPEG file, its icon actually shows a tiny image of the photograph; this type of icon is called a thumbnail. Examples are shown in the file manager window in Figure 3-2.

Figure 3-2. Thumbnails in the Pictures folder

Let’s look at few of the things you can do in the file manager. First, here are the main parts of the window and what they do:

The Nautilus file manager window also provides pop-up menus for fast and convenient access to specific tools. To open a pop-up menu, right-click in a file manager window. The choices listed in this menu depend on where you right-click. For example, when you right-click on a file or folder, you can choose things to do with the file or folder. When you right-click on the background of a view pane, you can choose the way things look in the view pane.

Looking through the hierarchy of folders

As you use JDS, you soon build up so many files that you want to organize them by task or topic. It’s a good idea to think right from the start about how to break up files into different folders.

The Tree view of the file manager’s side pane, discussed in the previous section, can be very useful to help you navigate among different directories. For instance, if you type a slash (/) into the Location window and press Enter, you see a tree in the side panel, similar to the one shown in Figure 3-3. Most of these files are infrastructure to keep the system working and should not be changed by users, but browsing the hierarchy can get you used to using the file manager. Click on the triangle to the left of any folder. This expands the list of folders to show the contents of the folder you clicked on and turns the arrow into a triangle pointing down. Click on this triangle, and the list of folders contracts again.

Figure 3-3. The JDS directory

In JDS, the This Computer icon, shown in Figure 3-4, lets you access all the drives on your computer (such as the CD reader), open documents, launch programs, and customize your system. It’s the JDS equivalent to My Computer in Microsoft Windows. We looked briefly at This Computer in the previous chapters, and now we can explore it in detail.

Figure 3-4. This Computer icon

This Computer is a Nautilus window, like the Documents window. When you double-click on the icon, it opens a window, with the location called system:///. We can see this in the Location area of the window, shown in Figure 3-5. A recap of the items in the This Computer folder is shown in Table 3-2.

Figure 3-5. This Computer window, or System Folder

Any time you manipulate and save data or some other setting on your computer, you are interacting with a file. The file extension or suffix (the final part of the filename, following a period) are the way in which most desktop systems know how to handle files—that is, which files go with which applications. In Table 3-3, we list some common extensions for files and what they mean, to give you an idea how this works.

If you have used Windows or Mac OS, you may want something similar to Windows Explorer or the Finder Icon on JDS. You can do this in a few steps. Although many JDS applications offer basic file management, a home directory accessible through the file manager can provide the most powerful tool for organizing your files. This window allows you to create new folders, copy and move files between folders, delete files, and rename files.

First, place your cursor on some empty space on your JDS desktop area. Then right-click your mouse. You notice a small window called a Context menu. From the Context menu, choose New Launcher. (See Figure 3-6.)

Figure 3-6. Context menu: choose New Launcher

Next, you see another window titled Create Launcher. Type:

               Home

in the Name and “Generic name” input areas (Figure 3-7). Next, go to the Type area and click on the right side of the bar with the two small arrows pointed up and down. Chose Link from that menu.

Figure 3-7. Create Launcher window

Next, type the path of your home directory, /home/your-directory_name. You can browse to it (using the button to the right of the URL) if you don’t know the name of your home directory.

After you fill in the text fields, press the icon button and choose one that suits you. In our example, we selected the yellow folder with the little house next to it, titled Blueprint-gnome-fs-home.png, in Figure 3-8.

Figure 3-8. Choose an icon

After you click OK, your Create Launcher window should look similar to the one in Figure 3-9. If everything looks correct, click OK, and you should have an icon on your desktop that resembles the icon you selected. When you click on it, you see a window with your directories in it, similar to Figure 3-10.

Figure 3-9. Completed Launcher window

Figure 3-10. Home Directory window and Launcher icon

You now have a shortcut to your Home Directory, similar to that in Windows Explorer.

Adding applications to the Panel and Launch menu

Let’s look at a useful customization you can make to your desktop. The second item from the bottom of the System Tools menu, the Terminal, represents a tool many people use regularly. If you find a need to go beyond the menus and icons on your desktop and enter some Linux commands by hand, the Terminal may prove important to you. So here we show how to add a launcher for the Terminal to make it easier to start up.

You can see in Figure 3-11 that a Terminal launcher was added to the panel on the bottom of the screen: it appears as an icon, near the center of the bottom of the figure. Clicking this icon has exactly the same effect as choosing Launch → Applications → Systems Tools → Terminal.

Figure 3-11. Terminal Launcher on panel

Figure 3-12 summarizes the menus you have to pull up to add the Terminal icon to the panel.

Figure 3-12. Adding Terminal to the Gnome panel

Start by finding an open spot on the Gnome panel and right-click your mouse. The menu in Figure 3-13 appears. We refer to this menu as the Panel menu.

Figure 3-13. Panel Menu

At this point, you can select the menu entry Add to Panel. This puts up a menu that gives you a large selection of tools, many of which you cannot find in the Launch menus.

Figure 3-14 shows the Add to Panel selections. Notice the menu item that says Launcher from menu. That selection allows you to add anything you want from the main Launcher menu. You can see the available options by selecting the Panel menu and exploring the applications.

Figure 3-14. Add to Panel selections

Let’s go ahead and add the Terminal to the Panel and move it into position. Right- click on the Panel and the Context menu appears. Use your mouse to reach the Terminal by selecting Add to Panel → Launcher from menu → System Tools → Terminal. Release your mouse button to select the Terminal.

Another way to achieve the same effect is to follow the cascading menus as if you were selecting Terminal from the Launch menu. Then right-click on Terminal and select “Add this launcher to panel.”

As you can see in Figure 3-15, the Terminal icon appears to the left of the Add to Panel menu. You can similarly add any item in the main menu or any of the applications on the Add to Panel menu.

Figure 3-15. Terminal icon added to the Gnome panel

If you want to move a panel icon into another position, place your mouse pointer over the icon, such as the Terminal, right-click it, and select Move. The icon will float along the panel, following your mouse (note that the cursor changes its shape into a cross). Click when you have finished moving it to anchor the icon, then right-click the icon again and select “lock.” Your icon now appears in the same location any time you log in to JDS.

Utilities you can add to the Gnome JDS panel

Let’s look at some popular utilities that you may use every day and may want to add to your panel. The first set comes from the Accessories menu. See Figure 3-16.

Figure 3-16. Accessories you can add to your Gnome panel

If you do not have a clock on your panel, select the Clock icon, and it immediately appears on your panel.

The Clock icon on your panel has options you can select by right-clicking the icon and selecting Preferences. You can have the icon show seconds, the date, UTC (Greenwich) time, and/or the city. When the date and time appear on the panel, you can drag them and paste them into a document.

Now let’s look at Figure 3-17 and consider some actions you may want available on your desktop.

Figure 3-17. Actions you can add to your Gnome panel

As you can see, you have some interesting choices. Force Quit uses the Unix command xkill. When you use this, it ends a process that is running on the desktop. This is normally not a good way to close a window; usually you should click on the button with the cross at the top of the window, or close it using the File menu. But once in a while you find a window that’s hung and won’t respond to anything you ask it to do; Force Quit is valuable for these extreme situations.

For example, suppose you encounter a spike in your Internet connection when you are receiving mail. This can cause the screen to freeze until the Internet connection recycles. If you do not want to wait for the connection to recycle, you can clear the desktop by pressing the Force Quit icon and by placing the cursor over the application. When you click your mouse, a small dialog box will appear and ask if you want to force the application to quit. Press OK to terminate the application.

The Screenshot icon has many uses, especially for writers or people who want to do art work from images off the Web. If you come across an image on your desktop you want to capture, select the Screenshot icon, and it lets you save a screenshot in the directory html under your home directory.

If you try out an icon and decide you no longer want it, right-click on it and select Remove From Panel.

Let’s look at one more menu of items you can add to your panel; you can try out the remainder on your own. Just remember that whatever you add, you can also remove with a right-click of your mouse.

You may find the Utility menu in your Add to Panel selections valuable for two reasons. First, you may delete an icon by mistake, such as your Window List. Second, depending on the kind of work you do, items from the Utility menu can increase your productivity.

Let’s look at the Window List icon, which reserves space on your panel to show what open applications exist on your desktop. For example, you may have Mozilla, StarOffice Writer, and Email open but minimized. If so, you can see that they are active and minimized. Without the Window List, all you can see is which applications are minimized in one particular virtual workspace.

Tip

Even experienced Linux users accidently delete icons from their panels. Rest assured that you can replace them by going to the Utility menu to add them back. (See Figure 3-18.)

Figure 3-18. Utilities you can add to your Gnome panel on the left side

If you use a laptop, you may want the Battery Charge Monitor on your panel. Palm Pilots users can syncronize their PDAs by adding the Pilot Applet. Most of the remaining icons are self-explanatory.