PREFERENCES FOR THE GNOME TERMINAL EMULATOR

Programs that antedate graphical user interfaces often rely on a terminal emulator for input and output facilities -- the input from the keyboard alone, and the output as if to a character-oriented display. Specifically, the GNOME terminal emulator imitates the facilities of a DEC VT220 (roughly). On MathLAN, the prime examples of programs that depend on a terminal emulator are shells (command-language interpreters, such as bash and the C shell) and MATLAB.

The GNOME terminal emulator comes with a configuration tool, which you can use to modify its appearance and behavior. To start the configuration tool, move the mouse pointer onto the word Settings in the menu bar at the top of a terminal window, click the left mouse button, move the mouse pointer onto the word Preferences on the menu that appears, and click the left mouse button again. A window pops up, with its initial panel (General) displaying some of the configuration options, and other panels containing other options represented by tabs (Image, Colors, Scrolling). Moving the mouse pointer onto a tab and clicking the left mouse button brings up the configuration panel whose name is on the tab.

Since most of the configuration options satisfy very specialized needs or tastes, this handout deals only with the ones that are most commonly changed.

Type font

The type font used by default in the GNOME terminal emulator, which is called ``fixed,'' is rather small and lightweight, making it difficult to read, especially on a high-resolution display. The font-configuration option on the General panel allows you to substitute a different font.

The name of the current font is displayed in the text field labelled Font:, and one way to select a different font is to edit that text field to contain the name of the font you want. Unfortunately, most of the fonts available on MathLAN have cumbersome names, such as -adobe-courier-medium-r-normal--12-120-75-75-m-70-iso8859-1, so it's usually easier to get the machine to pick out the one you want than to find it and type in its name yourself. That's what the button labelled Browse..., to the right of the text field, is for.

Move the mouse pointer onto the Browse... button and click the left mouse button. A new window entitled Pick a Font appears, offering three tabbed panels. Each panel presents a different way to specify a font; we'll consider only the Font panel, which is perhaps the easiest to use.

At the left of the window is a list of font families, long enough to require a scroll bar. Moving the mouse pointer onto any item in this list and clicking the left mouse button causes a sample of the font to appear in the text field labelled Preview:, at the bottom of the window. For the terminal emulator, you should definitely select a ``fixed-width'' font, in which every character takes up the same amount of space along a line, rather than a ``proportional-width'' font in which, say, a capital W is much wider than a lower-case i. (The reason is that the terminal emulator does not compute the correct spacing between letters when a proportional-width font is used.) Clean, Courier, and Lucida Typewriter are popular choices.

Selecting the font family also changes the contents of the lists labelled Font Style: and Size:, presenting you with the available alternatives within that font. The font style controls the weight (light, medium, or bold) and slant (unslanted, italic, or oblique) of the letters. Move the mouse pointer onto the desired entry in each of these lists and click the left mouse button to select the font style and size. When the preview matches what you want to see in your terminal emulator, move the mouse pointer onto the button labelled OK at the bottom of the Pick a Font window and click the left mouse button. The window disappears, and the name of the particular font that you have selected is automatically entered in the Font: text field in the configuration tool.

Foreground and background colors

The default configuration for the GNOME terminal emulator specifies ``white'' characters against a black background, where ``white'' is actually implemented as medium gray. Like the default font, this unwisely chosen color scheme greatly reduces legibility.

Here's how to change the color scheme to something more appropriate. Move the mouse pointer onto the word Colors on the third tab in the configuration tool and click the left mouse button. On the panel that appears, you'll see a choice widget labelled Fore/Background Colour:. Move the mouse pointer onto the widget and click the left mouse button; a menu of five choices appears. Unless one of the four canned color schemes listed there appeals to you (Black on light yellow is perhaps the least obnoxious), move the mouse pointer onto the phrase Custom colors and click the left mouse button.

You now have the opportunity to select any colors you want for the foreground (that is, the visible text) and background.

To select the foreground (text) color, move the mouse pointer onto the color sample labelled Foreground color: and click the left mouse button. A new window entitled Pick a color appears.

In this window, think of a color as being determined either by its hue, its saturation, and its value (that is, its brightness), or by the intensities of its red, green, and blue components. On the color wheel at the left of the window, hue is measured in degrees counterclockwise from the upwards vertical axis (so that, for example, 60o denotes a yellow hue and 290o a bluish-violet one). Saturation, value, and component intensities are scaled into the interval from 0.0 (minimum) to 1.0 (maximum).

You can specify the color you want in several different ways:

The selected color appears in the right half of the rectangle below the color wheel. (The left half contains that color that it will replace.) When the color is correct, move the mouse pointer onto the button labelled OK and press the left mouse button. The Pick a color window disappears, and the color sample labelled Foreground color: is now the newly selected color.

Go through the same process to select the background color. You can see what the terminal window looks like with the currently selected color combination by moving the mouse pointer onto the button labelled Apply at the bottom of the configuration tool and clicking the left mouse button. The terminal window changes immediately to show the new colors.

Terminal classes

When you are satisfied with the font, the colors, and anything else that you have tinkered with in the configuration tool, you can store the configuration for future use by moving the mouse pointer onto the button labelled OK at the bottom of the configuration tool window and clicking the left mouse button. The resulting configuration file is consulted whenever you subsequently start the GNOME terminal emulator.

Before you click OK, however, you might want to consider defining a separate terminal class for the configuration that you have specified. In effect, you can give a name to this configuration; by later specifying this name when you start the GNOME terminal emulator, you can direct it to use that configuration.

This feature is useful only if you plan to use different configurations on different occasions. For instance, you might have a Classroom configuration, using a larger-than-usual font, for occasions in which the terminal emulator window is displayed on the overhead monitors in the department's classrooms.

To give the configuration a new name, edit the text field labelled Terminal Class at the top of the General configuration panel so that it contains the new name. Then move the mouse pointer onto the button labelled OK at the bottom of the configuration tool window and click the left mouse button.

A pop-up window sometimes appears at this point, noting that you have changed the class of the terminal-emulator window that you started from and asking whether to impose the changes on that window. Move the mouse pointer to the Yes button if you want to store the new configuration and change the appearance and behavior of the existing window, the No button if you want to store the new configuration without changing the existing window, or the Cancel button if you don't want to store the new configuration after all. Then click the left mouse button.

Subsequently, whenever you want to configure a terminal-emulator window as belonging to a particular terminal class, you can move the mouse pointer onto the word Settings in the menu bar at the top of the window, click the left mouse button, move the mouse pointer onto the word Preferences on the menu that appears, click the left mouse button again, move the mouse pointer onto the downwards-pointing triangle to the right of the Terminal Class text field, click the left mouse button again, move the mouse pointer onto the name of the terminal class you want, click the left mouse button again, move the mouse pointer onto the OK button, and click the left mouse button one last time. If this seems like too much mousework, you can instead use a command-line argument, as described in the next section.

Command-line options

The executable file containing the GNOME terminal emulator is /usr/bin/gnome-terminal, and you can start it from a shell just like any other executable program, by typing the file name at the shell prompt.

You can add some command-line options, of which the following are particularly useful:

Launching from the front panel

If you can start the GNOME terminal emulator by moving the mouse pointer onto some icon on the front panel and clicking the left mouse button, it might be interesting to find out exactly what command is being executed. If you move the mouse pointer onto that icon, click the right mouse button, move the mouse pointer onto the word Properties on the menu that appears, and click the left mouse button, the exact text of the command is displayed in one of the text fields shown in the window that appears.

You may find, for instance, that the command includes options that force the terminal emulator to use a particular font, foreground, and background. If you have other preferences, you may want to edit that text field, removing these options or replacing them with something like --tclass=MyFavorite.

If you plan to use different configurations frequently, you might even want to have two or more launchers on your front panel, both starting gnome-terminal, but with different --tclass options. To make an extra copy of your existing front-panel launcher, move the mouse pointer onto it, press and hold the left mouse button, drag to the position on the front panel that you want the copy to occupy, and release the mouse button. You can then bring up the Properties window and edit the Command: text field of the copy, as just described.

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created August 2, 2000
last revised June 28, 2001

John David Stone (stone@cs.grinnell.edu)