Arman Danesh and Michael Jang X Windowsacademy.delmar.edu/Courses/...GNOME_and_X-Windows.pdfCustomizing Xterm ... PM Page 161. 162 T his chapter looks at some X Windows and GNOME applications

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Mastering™ Linux

Arman Danesh and Michael Jang

Chapter 9: Using Applications with GNOME andX Windows

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C H A P T E RN I N E

Using Applications withGNOME and X Windows

■ Using Xterm

■ Customizing Xterm

■ X Windows Applications

■ X Windows Utilities

9

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This chapter looks at some X Windows and GNOME applications and howthey can be run and used within the GNOME desktop. These applications includexterm, the GNOME file manager (called Midnight Commander), a graphics pro-gram called The GIMP, and several X Windows utilities.

These applications have been selected based on one of two criteria: They areuseful in everyday Linux operations, or they are representative of the power orrange of many Linux applications.

This chapter should give you the confidence to begin experimenting with otherX Windows applications.

Using XtermWhile X Windows puts a nice-looking and user-friendly face on Linux and allowsthe creation of fully graphical applications, the fact remains that as a Unix clone,Linux is a command-line-oriented operating system.

Although it is possible to use Linux for everyday work without ever using thecommand prompt, to take advantage of the real power and flexibility of a Unix-like operating system, you need to make at least occasional forays into the worldof the command line.

Fortunately, this doesn’t mean abandoning the ease of X Windows. The xtermprogram provides a command prompt window that is fully integrated into the X Windows environment, with a scroll bar, a resizable window, and the ability tocopy and paste with other X Windows applications—all features that a standardLinux console lacks.

NOTE You can launch an xterm window in Red Hat Linux 7 by selecting Regular XTermfrom the System submenu of the Programs menu. GNOME includes a clone ofxterm, known as GNOME terminal. Nevertheless, this chapter describes xterm indetail, because it is available in other Linux graphical environments, including KDE.Many of the same commands work for GNOME terminal; some require slightchanges such as an extra dash. Only significant functional differences betweenthese two types of terminals are noted in this chapter.

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If you want to launch additional xterm windows, you can also do so from thecommand line of another xterm window using the command

$ xterm &

or, if you find that for some reason xterm isn’t on your path, use the command

$ /usr/X11R6/bin/xterm &

TIP You can locate most files easily with the locate command. If you want to find thedirectory where xterm is located, run the locate xterm command. Unfortu-nately, locate doesn’t work with recently created or moved files; in that case, usethe find command as described in Chapter 13, “Introducing Linux Commands.”

Alternatively, you can launch additional GNOME terminal windows from thecommand line of another xterm window using the command

$ gnome-terminal &

or you can just click the terminal icon on the default GNOME panel.

By default, this opens a window that is 80 characters wide and 24 lines deepwith a scroll bar. The window can be resized to provide more space for viewinginformation and working. As shown in Figure 9.1, the default color scheme fornew xterm windows in Red Hat Linux 7 is black characters on a white back-ground. The default title of the window specifies the current user and directory.

F I G U R E 9 . 1 :

An xterm window

Using Xterm

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Customizing XtermThe xterm program is highly customizable. Among other things, you can changethe following characteristics:

• The window’s font

• The color scheme

• The default window size

• The placement of new windows on the screen

• The title of the window

This section will look at these options and describe how to use them whenlaunching new xterm windows.

At first it might seem that this flexibility has no real value, but in reality it does.On different monitors, different color combinations produce the most readabletext, so being able to change the color scheme is a valuable feature. Also, if youregularly use several xterm windows for different tasks (such as running top formanaging system performance, reading your e-mail, and managing your files),being able to quickly identify which window is currently being used for whichtask makes switching between open windows much easier.

Flags and Arguments: A Quick Unix PrimerBefore going forward, you need a quick tutorial about how Unix commands work. A com-plete introduction to Unix and Unix commands as used in Linux comes in Chapter 13.

To execute a program (or command), you simply need to type the name of the program(and possibly the complete location of the program) and press the Enter key.

For instance, to launch xterm, you can use the command

$ xterm

or, if the directory where xterm is located is not on your path, use the command

$ /usr/X11R6/bin/xterm

The path is where Linux searches for commands. You can find the path with this command:

$ echo $PATH

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Most programs either require or can accept information that alters the way they behave orprovides information to be processed. Two types of information can be provided to a com-mand: flags and arguments.

Arguments are information provided to the program to be processed; they can be any-thing from filenames to text to search for.

Flags are options that alter the behavior of a program. They appear after the command,separated by one or more spaces and preceded by a dash. For instance, the flag -helpcauses xterm to print out a help message:

$ xterm -help

usage:xterm -options ... -e command args

where options include:

-help print out this message-display display name X server to contact-geometry geom size (in characters) and position-/+rv turn on/off reverse video-bg color background color-fg color foreground color-bd color border color-bw number border width in pixels-fn fontname normal text font-iconic start iconic-name string client instance, icon, and title

strings-title string title string-xrm resourcestring additional resource

specifications-/+132 turn on/off column switch

inhibiting-/+ah turn on/off always highlight-/+ai turn on/off active icon

Complex flags can also be created to provide information that the flag needs to functioncorrectly. For instance, to set the xterm title, you use the -T flag, but you also need to pro-vide the text that you want to appear in the title bar. The command

$ xterm -T Email

creates an xterm window with the word Email as the title. On the other hand, one simpleflag is the ampersand (&). For example, the command

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$ xterm &

opens another xterm window and returns the current xterm window to the command-line interface.

Arguments, on the other hand, are not configuration options but information provided toa program to be processed. Arguments are not preceded by a dash as are flags. Argu-ments are often the names of files to be opened, processed, or edited—as in the follow-ing example, which indicates that the file testfile should be opened for editing with theeditor emacs:

$ emacs testfile

Setting the Color SchemeUsing a variety of flags, it is possible to set almost all aspects of an xterm win-dow’s color scheme from border color to the color of the cursor. This sectionexamines the main elements of the color scheme: foreground color, backgroundcolor, and cursor color.

Understanding X Windows Colors

Before looking at the specific flags used to set colors of an xterm window, youneed to look at how colors are referred to in X Windows.

Colors in X Windows are specified in RGB (red-green-blue) format. RGB formatconsists of ordered triplets of numbers, with each number having a value from 0 to255. The numbers represent the value of the red, green, and blue channels respec-tively, with 0 representing no color and 255 representing the highest possible valueof the color.

Luckily, you don’t need to figure out the color channel combinations to getyour desired color. The work has already been done and is stored in a file that X Windows uses to map color names to their numerical triplets. This file, nor-mally called rgb.txt, is usually found in the directory /usr/X11R6/lib/X11/.

A selected list of values in the Red Hat Linux 7 rgb.txt file appears here tomake it easy to experiment with colors as you work through this section:

snow GhostWhite PapayaWhip LemonChiffon

AliceBlue LavenderBlush MistyRose white


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DarkSlateGray DimGray gray MidnightBlue

NavyBlue SlateBlue blue SteelBlue

turquoise cyan DarkGreen SeaGreen

LawnGreen green GreenYellow DarkKhaki

LightYellow yellow gold RosyBrown

IndianRed sienna beige wheat

tan chocolate DarkSalmon orange

tomato red DeepPink pink

maroon magenta violet orchid

purple DarkCyan DarkRed LightGreen

NOTE Depending on the color depth of your video display and the applications you arerunning, you may find that the colors you use don’t appear quite the way youexpect. This is due to video card limitations and differences between systems.

Background and Foreground Colors

Setting background and foreground colors allows you to control the appearanceof the text on your screen. Text appears in the foreground color while the back-ground color, logically, is assigned to the background of the window.

The usual default xterm window is black text on a white background. Use the -fg and -bg flags to set the foreground and background colors:

$ xterm -fg white -bg black &

This command provides exactly the reverse color scheme of the default xtermwindow, causing the background to be set to black and the foreground to white.The result looks like Figure 9.2.

NOTE The -bg and -fg flags are not specific to xterm. In fact, they are standard X Win-dows flags that can be used to change the color schemes of most X Windowsapplications. However, these flags do not work for the gnome-terminal com-mand. To find the right switches for GNOME terminal, run the gnome-terminal--help command.

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Cursor Color

If you tried the last example for setting colors, you probably noticed that the cur-sor stayed the same color as the default xterm color scheme. You can change thiscolor as well, using the -cr flag. For instance, if you want a dark blue cursor, youmight use the command

$ xterm -bg white -fg black -cr MidnightBlue &

Setting the Window Size and LocationWhen you open an xterm window (or any other application’s window, for thatmatter), the size of the window is set to a default size and the location of the win-dow is determined by the configuration of your window manager (you will seexterm commands in key files when you read Chapter 12, “Advanced X WindowsConfiguration”).

However, you can specify the exact size and placement of windows in X Win-dows using the -geometry flag. This flag is a standard X Windows flag (like -bgand -fg) and works with most X Windows programs.

The basic syntax of the flag is -geometry widthxheight+x+y. The variables in thiscommand are shown below:

• width specifies the width of the window in pixels.

• height specifies the height of the window in pixels.

F I G U R E 9 . 2 :

Controlling the colorscheme


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• x specifies the horizontal placement of the window as an offset in pixelsfrom the left side of the display.

• y specifies the vertical placement of the window as an offset in pixels fromthe top of the display.

Xterm accepts the use of the -geometry flag but handles the information in asomewhat nonstandard way. When you think about it, specifying the height andwidth of a terminal window in pixels doesn’t make a lot of sense. Instead, xterminterprets width and height as the number of columns and rows of characters todisplay and sizes the window according to the font being used.

The default window size is 80 columns by 24 lines of characters. But what ifyou want a small 10-character by 10-character window to be placed 200 pixelsfrom the left side of the screen and 300 pixels down from the top of the screen?You could use the command

$ xterm -geometry 10x10+200+300 &

to get a window like the one in Figure 9.3. Note the position of the window rela-tive to the left edge and the top of the screen.

F I G U R E 9 . 3 :

Using the -geometry flag

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NOTE The corresponding command for the GNOME terminal is gnome-terminal --geometry=10x10+200+300 &. However, the effect of this command is limitedsince GNOME terminals have a minimum width of 25 columns.

By adding the -fg and -bg flags, you can also change the default color schemeat the same time you define the size of the window when it opens:

$ xterm -geometry 10x10+200+300 -fg DarkRed -bg cyan &

The result looks like Figure 9.4.

Setting the Window TitleAs mentioned earlier, it is useful to be able to set the title of an xterm window tohelp identify what different windows are being used for. The easiest way to setthe title is with the -T or -title flag (they are the same). The command

$ xterm -title Email &

creates an xterm window with the title Email, as would the command

$ xterm -T Email &

In order to create titles consisting of more than one word (in other words, con-taining spaces and other separators), you need to quote the title so that xtermknows which part of the command to treat as the title. If you prefer to use the titleMy Email, use the command

$ xterm -T “My Email” &

By default, the name of an xterm or GNOME terminal window in Red HatLinux 7 is the name of the current working directory unless, as you will seebelow, an application is specified to run inside the xterm window when it opens.

F I G U R E 9 . 4 :

Combining the -geometryflag with the color flags


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NOTE Corresponding commands for the GNOME terminal are gnome-terminal -tEmail or gnome-terminal --title Email.

Running an Application in an Xterm WindowWhile the purpose of an xterm window is to use the command line to executecommands, you may want certain character-mode programs to run by defaultwhen you launch the xterm window. For instance, if you always keep top runninginside an xterm window while you work, you might want to have top launchwhen you open its xterm. This is done with the -e flag:

$ xterm -e top &

This command opens a window like the one in Figure 9.5.

When the program running inside the window quits, the xterm window closes.

It is important to note that the default window title when you use the -e flag inxterm is the name of the program launched with the -e flag.

NOTE While the -e flag works for the gnome-terminal command, it does not set thedefault window title.

F I G U R E 9 . 5 :

Launching top when anxterm window opens

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Setting the FontThe default font used by xterm is usually quite readable and suited to the averagemonitor. But if you have a particularly large or small monitor or use an unusuallylow or high resolution, you may find it wise to change the font you use in yourxterm windows.

In order to do this, use the -fn flag. But how do you refer to fonts? Fonts arereferred to by names that can be as simple as 7x13, which indicates 7 pixels wideand 13 pixels deep, or as complex as -sony-fixed-medium-r-normal--24-230-75-75-c-120-iso8859-1, which indicates the 24-point Latin character set, mediumweight, Roman-style font named fixed from the Sony font foundry.

X Windows offers a program, xlsfonts, that provides a list of available fonts onyour X Windows system. To see a list of available fonts on your system, use thefollowing command in an xterm window:

$ xlsfonts | more

The | more part of the command allows you to page through the long list offonts by hitting the spacebar to move forward a page.

So, to choose the 10x20 font, use the command

$ xterm -fn 10x20 &

to get a window with a large font like the one in Figure 9.6. When you comparethis to Figure 9.1, note that not only is the font bigger, but the xterm window isalso bigger to accommodate the bigger font with the same number of rows andcolumns.

In theory, any of these fonts can be used with the -fn flag and the xterm com-mand. In practice, though, this doesn’t work. The nature of xterm is that it needsfixed-width fonts—that is, fonts in which all characters occupy the same amountof space regardless of their comparative sizes. In the world of Microsoft Win-dows, an example of a fixed-width font is Courier.

By contrast, many fonts are proportionally spaced. This means that a letter “i”takes up less space than a “w” because the latter is a wider letter. Xterm doesn’tdo a good job of handling these proportionally spaced fonts, as can be seen inFigure 9.7 where the selected font is from the Times family.


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Listed below are some of the common (and easy-to-type) fixed-width fonts thatare available in the X Windows distribution included with Red Hat Linux 7:

5×7 6×13bold 7×14bold 9×15bold

5×8 6×9 8×13 10×20

6×10 7×13 8×13bold 12×24

F I G U R E 9 . 7 :

Using a proportionallyspaced font

F I G U R E 9 . 6 :

The 10x20 font

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6×12 7×13bold 8×16

6×13 7×14 9×15

If you want to experiment with other fonts, use xlsfonts to see a list of fonts,select a font, and then use the xfd command to display the font in a window. Forinstance, to display the Sony font -sony-fixed-medium-r-normal--24-230-75-75-c-120-iso8859-1 that you saw earlier, use the command

$ xfd -fn -sony-fixed-medium-r-normal--24-230-75-75-c-120-iso8859-1

Notice the use of the -fn flag to specify the font name. The font will be displayedin a window like the one in Figure 9.8.

Click the Quit button to close the window.

F I G U R E 9 . 8 :

Displaying fonts with thexfd command


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Other FeaturesXterm offers many more features than the ones listed here. You can find out

about them in the xterm man page. A man (short for manual) page provides infor-mation about how to use a specific program. To access the xterm man page, usethe command

$ man xterm

in an xterm window. This command displays a man page like the one shown inFigure 9.9. Use the arrow keys to scroll through the man page. To exit the manpage, type q.

NOTE As of this writing, there is no man page available for GNOME terminal. For moreinformation about this program, open up a GNOME terminal window, then clickHelp ➢ GNOME Terminal Users Guide.

X Windows ApplicationsSo far, you have seen two of the most basic of X Windows applications in action:xterm and the GNOME file manager. If there were nothing more than this, it would

F I G U R E 9 . 9 :

The xterm man page

X Windows Applications

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reinforce the views of the naysayers who complain that X Windows doesn’t haveany applications and that Windows and the Mac OS are where the action is.

The reality, though, is that powerful, effective applications do exist for the X Win-dows environment. Even among the free tools out there are those that rival the fea-tures of commercial applications.

This section looks at two of the components of the GNOME Office Suite: TheGIMP graphical utility and the Gnumeric spreadsheet. Because these are bothlarge programs with extensive feature sets, this section just provides an overviewof the applications and what they do and then points to where complete informa-tion on the applications is available. Mastering an application like The GIMP orGnumeric, after all, would require a book in itself.

NOTE Other components of the GNOME Office Suite include the AbiWord word proces-sor, the Dia program for Visio-style diagrams and flowcharts, and the GNOME-PIMpersonal information manager.

The GIMPThe GIMP (GNU Image Manipulation Program) is an attempt to offer the Linuxcommunity a freely available, full-featured image-editing package to rival thelikes of Adobe Photoshop or Corel PhotoPaint. Figure 9.10 shows The GIMP run-ning with several of its dialog boxes and tools open. The GIMP is designed tointegrate tightly into GNOME and is considered the standard image-editingapplication for GNOME and a showcase of a high-powered GNOME application.GNOME is included as part of Red Hat Linux 7.

Offered under the General Public License, The GIMP is under constant develop-ment by Spencer Kimball and Peter Mattis at the University of California–Berkeley.

The GIMP includes all the tools expected of a full-featured image-editing pack-age, including numerous brush types, special-effects filters, intelligent scissors,Bezier selection, layers, transparencies, and 24-bit image support.

The GIMP also provides a plug-in mechanism. Numerous plug-ins are freelyavailable on the Internet to perform a variety of tasks, including despeckling,mapping to a sphere, creating mosaics, generating lens flares, and more.


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In addition, the most recent version (1.2.1) includes a downloadable manualthat provides the in-depth instruction and documentation often lacking in freesoftware. This is all available from The GIMP Web site at manual.gimp.org. Theversion included with Red Hat Linux 7 is 1.1.25.

You can run The GIMP from an xterm window with the command

$ gimp &

or

$ /usr/bin/gimp &

Alternatively, from the main GNOME system menu choose Programs ➢ Graphics ➢The GIMP to start The GIMP.

The GIMP starts up by displaying its toolbar. This window, shown in Fig-ure 9.11, offers access to a wide range of tools plus the main File menu.

F I G U R E 9 . 1 0 :

The GIMP


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Let’s take a quick look at some of the main tasks in The GIMP: opening andsaving images, cropping an image, and capturing a window to an image file. Tolearn the full set of The GIMP features, refer to the manual for the software that ison The GIMP’s Web site, mentioned earlier.

Opening Images

To open an image, click File ➢ Open. A dialog box like the one in Figure 9.12appears.

F I G U R E 9 . 1 2 :

The GIMP Load Image window

F I G U R E 9 . 1 1 :

The GIMP toolbar


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This dialog box works in a vaguely Mac-like fashion. Above the list of files, yousee the name of the current directory. You can click the directory name to get a listof its parent directories and, by selecting one of these, quickly change to thatdirectory.

Select the filename of your choice. If you are not sure which file you need, youcan preview a thumbnail by clicking the Generate Preview button in the Previewsection of the Load Image window. When you see the file that you need, click theOK button. The file appears in the viewer window and the dialog box closes.

Saving Images

If you want to save an image, you need The GIMP main menu. While working onan actual image, right-clicking anywhere in the image brings up the completemenu for The GIMP, like the one shown in Figure 9.13.

To open the Save Image dialog box, click File ➢ Save As from The GIMP mainmenu. The result shown in Figure 9.14 is similar to the Load Image dialog box.Directory navigation works in the same fashion; you select existing filenames byclicking them in the file list, and clicking OK saves the current file to the namedisplayed in the Save File field.

If you want to save the image to a new filename, simply type the name youwant in the Selection field.

When saving an image, you also want to specify the type of image. In the middleof the dialog box is the Determine File Type button. By clicking this button, you canview a list of available file types. Select the file type you desire from the list. Onceyou are ready to save your file, click OK.

F I G U R E 9 . 1 3 :

The GIMP main menu


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Cropping an Image

Cropping an image is a simple process: Turn on cropping, select the area you wantto crop, and press the Crop button in the Crop & Resize Information window.

To turn on cropping, right-click an image. In the menu that opens, select Tools ➢Transform Tools ➢ Crop & Resize. To select an area for cropping, drag out a rec-tangle with the left mouse button in the viewer window. Figure 9.15 shows animage displayed in the viewer window with a rectangle indicating where the userhas dragged the mouse.

F I G U R E 9 . 1 5 :

Selecting a crop area

F I G U R E 9 . 1 4 :

The GIMP Save Image window


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Once you have selected an area to crop, simply click the Crop button in theCrop & Resize Information window. The result would be something like Fig-ure 9.16 for the previous example.

If you don’t like the results of your cropping, right-click the image. In the menuthat opens, select File ➢ Revert to return to the original image.

Capturing a Window

One of the popular uses of The GIMP is to create screen shots. If you want to cap-ture an open window to an image file, you can do this using the Acquire ScreenShot feature. When you have a window that you want to capture, click File ➢Acquire ➢ Screen Shot, which opens the Screen Shot dialog box like the one inFigure 9.17.

You can grab an individual window or the entire contents of your desktop. Tograb an individual window, select Single Window. Click OK, then click the win-dow of your choice.

If you don’t want to show the window frame or title, deselect With Decora-tions. For example, if you were to grab an xterm window of the top utility, withbackground and foreground colors reversed, the result would look almost as ifyou were not using the X window, as shown in Figure 9.18.

F I G U R E 9 . 1 7 :

The Screen Shot window

F I G U R E 9 . 1 6 :

The result of cropping


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Alternatively, you can grab the entire contents of your desktop in the ScreenShot window by selecting Whole Screen. Set the Seconds Delay box to give youtime to close or open other windows before The GIMP makes a screen shot ofyour desktop.

Once you have grabbed a window, the image of that window appears in theviewer window, and you can save it like any other image in The GIMP.

GnumericGnumeric is another component of the GNOME desktop environment, designedto manage numeric data through spreadsheets. This program offers Linux users afreely available full-featured spreadsheet program that can exchange data withother spreadsheet programs such as Microsoft Excel. It is installed by default onRed Hat Linux 7.

Offered under the General Public License, Gnumeric is under constant develop-ment by a number of independent developers, most prominently Miguel de Icazaand Jody Goldberg. Since the current version is 0.63, it is not “officially” ready forrelease; however, support as of this writing can be purchased from Ximian athttp://www.ximian.com.

Gnumeric includes most of the tools of normal spreadsheets. You can find moreinformation about Gnumeric at http://www.gnome.org/gnumeric, including a pub-lic list of “pending tasks.” If you are interested, you can contribute to the devel-opment of this spreadsheet.

F I G U R E 9 . 1 8 :

A screen shot of top


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Using Gnumeric

Let’s take just a quick look at using Gnumeric. This spreadsheet is part of a num-ber of standard Linux distributions, including Red Hat Linux 7. You can run itfrom an xterm window with the command

$ gnumeric &

or with the command

$ /usr/bin/gnumeric &

Alternatively, you can run Gnumeric by clicking the Main Menu button andchoosing Programs ➢ Applications ➢ Gnumeric.

Gnumeric starts with a blank spreadsheet, as shown in Figure 9.19. Like otherspreadsheet programs, Gnumeric includes a number of icons that serve as short-cuts to various tools for editing and creating formulas.

Now you can open up a Gnumeric file when you click the File ➢ Open com-mand. This takes you to a Load File dialog box where you can navigate to the filethat you need, in Gnumeric XML file format.

F I G U R E 9 . 1 9 :

The Gnumeric spreadsheet


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Importing Files

From the File menu, you can import Gnumeric data from a number of other fileformats. When you click File ➢ Import and then select a file, Gnumeric promptsyou to place the file in one of the following five categories:

HTML File Made By Gnumeric If you saved a spreadsheet as an HTMLfile from Gnumeric, you can re-import data from the HTML file.

Text File Import One common way to distribute data is in a text file,where commas separate each data point. This is sometimes known ascomma-delimited format. The Text File Import option allows Gnumeric touse each comma to assign data to different cells.

SC/xspread File Import Gnumeric can import data from other spread-sheet formats, including those based on Microsoft Excel, IBM (Lotus) 1-2-3,and Applixware spreadsheets.

Data Interchange Format (DIF) Import The Data Interchange Format is acommon way to exchange data between databases and spreadsheets. It isalso used as a common translation medium between spreadsheets whenthere are no other compatible file formats.

Simple Text Gnumeric can import text files as simple text. Each line in thetext file is assigned to consecutive cells.

Exporting Files

You can share Gnumeric files with people who use other spreadsheets. Gnumericsupports exporting to 14 different file formats. To set up this process, choose File ➢Save As. Enter the desired filename in the Selection box. Click the File Format boxto see your options, as shown in Figure 9.20. Select a file format, then click OK.

NOTE The ability to exchange files between different applications is typically less thanperfect. This premise holds true for Excel and Gnumeric. Some users have success-fully imported Excel 2000 files into Gnumeric; however, not all functions of thesetwo programs are compatible.


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Formulas

The heart of any spreadsheet application is its formulas. By definition, formulasare defined and embedded in specific cells in a spreadsheet. Formulas includefunctions such as SUM, which totals the cells in a specified range. When Gnumericconverts files from other spreadsheets, it converts these functions as well. If youdo not recognize a Gnumeric function, get help by choosing Help ➢ GnumericFunction Reference.

X Windows UtilitiesBefore closing this chapter, let’s look at a few handy X Windows utilities and howto use them. These utilities are as follows:

• gedit

• xclock

• xcalc

F I G U R E 9 . 2 0 :

The Save Workbook As window

X Windows Utilities

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Using GeditGedit is a GNOME application that provides functionality similar to Windows

Notepad. You can use it to open and change the contents of plain text files, searchand replace text, and create new files.

Admittedly, as Figure 9.21 shows, the gedit interface is a bit spartan, but forquick editing of simple text files, it does the trick.

You can launch gedit with the command

$ gedit &

or, if gedit is not on your path, with the command

$ /usr/bin/gedit &

or you can click the main GNOME System menu and choose Programs ➢ Appli-cations ➢ Gedit.

The interface is simple. Across the top is the toolbar with self-explanatory buttonsfor loading and saving files, cutting, copying, pasting, and searching for text.

F I G U R E 9 . 2 1 :

The gedit window


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To load an existing file, click the Open button or choose File ➢ Open. A dialogbox appears, where you can browse for and select a file to open. When a file isopened, it appears as shown in Figure 9.22.

You can save a file you have opened by clicking the Save button on the toolbaror by choosing File ➢ Save.

The Find button on the toolbar brings up the Find dialog box shown in Fig-ure 9.23. You can also open this dialog box by choosing Edit ➢ Find.

F I G U R E 9 . 2 3 :

The Find dialog box

F I G U R E 9 . 2 2 :

The results of loading a file

X Windows Utilities

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Using this dialog box is relatively simple: Fill in the text to search for and clickthe Find button. You can also indicate if you prefer to start your search at thebeginning of the document or the current cursor position and whether or not thesearch should be considered case-sensitive.

Replace takes things one step further. You can open the Replace dialog box byselecting Edit ➢ Replace. This dialog box looks like the Find dialog box exceptthat it has an additional field for indicating the text with which to replace eachfound item. In addition, you can use the Replace button to indicate that you wantto be prompted before replacing any text.

X Windows ClocksYou have probably noticed the clock that appears in the GNOME panel. Someusers, though, like to see a larger digital or analog clock on their desktop.

This can be achieved using the xclock program. Xclock is a basic clock programthat allows you to create an analog or digital clock. By default, xclock displays ananalog clock, so the command

$ xclock &

or

$ /usr/X11R6/bin/xclock &

creates a window like the one in Figure 9.24.

The -digital flag causes xclock to display a digital clock like the one shown inFigure 9.25.

F I G U R E 9 . 2 5 :

A digital xclock window

F I G U R E 9 . 2 4 :

The default xclock style


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The -digital flag is not the only flag accepted by xclock. The -hd and -hl flagshelp create a more interesting visual display for an analog clock. The -hd flag isused to specify a color for the hands of the clock, and the -hl flag specifies thecolor for the outline of the hands of the clock. (Remember the discussion of RGBcolors earlier? This is one instance where you would use RGB colors.)

For example, the command

$ xclock -hd yellow -hl green &

creates a clock that has yellow hands with green outlines as in Figure 9.26 (ofcourse, this is hard to see in the black-and-white reproduction you are looking at).

Notice the lack of contrast between the hands and the white face of the clock.This can be rectified with a standard X Windows flag: the -bg flag that you sawearlier in the discussion of xterm. By specifying a background color of black with

$ xclock -hd yellow -hl green -bg black &

you end up with something like Figure 9.27.

While the hands are now clearly visible, a new problem has arisen: The marksthat indicate the points of the clock are now invisible, since they are black andthey are drawn against a black background. These marks are considered part of

F I G U R E 9 . 2 7 :

Setting the backgroundcolor

F I G U R E 9 . 2 6 :

Setting the color of theclock’s hands

X Windows Utilities

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the foreground, and their color can be changed with the standard X Windows -fgflag. The command

$ xclock -hd yellow -hl green -bg black -fg cyan &

gives a result like Figure 9.28.

Using the GNOME CalculatorFinally, let’s take a quick look at the GNOME Calculator, the default GNOME cal-culator tool that should be available in every distribution of Linux that includesGNOME.

As you might expect by this point, you can run the GNOME Calculator withthe command

$ gcalc &

or with the command

$ /usr/bin/gcalc &

The GNOME Calculator can also be opened by selecting Simple Calculatorfrom the Utilities submenu of the main GNOME System menu.

The GNOME Calculator window looks like Figure 9.29.

The Calculator operates much as any standard scientific calculator does. It pro-vides all the expected scientific functions, including trigonometric and logarithmicfunctions, plus a memory. The actual use of such a calculator and its functions isnot really the subject of this chapter, and a full description of the meaning of thesefunctions is best left to a mathematics text.

F I G U R E 9 . 2 8 :

Setting the foregroundcolor


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Looking AheadBy now, you should be feeling fairly comfortable navigating your GNOME envi-ronment. You can control basic options of GNOME, you can launch applications,and you can manipulate windows.

As mentioned earlier, though, the power of both X Windows and GNOMEcomes from their flexibility and configurability.

Chapter 10, “Advanced GNOME Configuration,” looks at how to go about con-figuring GNOME to meet your personal needs. This includes customizing themain GNOME panel, changing your desktop appearance and themes, and per-forming other common GNOME configuration tasks.

F I G U R E 9 . 2 9 :

The GNOME Calculatorwindow

Looking Ahead

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Documents

Arman Danesh and Michael Jang X Windowsacademy.delmar.edu/Courses/...GNOME_and_X-Windows.pdfCustomizing Xterm ... PM Page 161. 162 T his chapter looks at some X Windows and GNOME applications