Abrindo Aplicativos Gráficos

métodos para abrir aplicativos de Interface gráfica do usuário, ou GUI, em vários ambientes.

Abrindo aplicativos gráficos a partir da linha de comando

Os aplicativos gráficos podem ser iniciados a partir de uma janela de terminal ou sessão de console simplesmente digitando o nome do aplicativo.

[fedorauser@localhost]$ firefox
Nomes de Arquivos x Nomes de Aplicativos

Os programas são abertos na linha de comando usando o nome do arquivo executável fornecido no pacote do programa. Uma entrada no menu da área de trabalho geralmente terá um nome diferente do arquivo que executa. Por exemplo, o utilitário de gerenciamento de disco GNOME aparece no menu como Discos, e o arquivo que executa é /usr/bin/gnome-disks.

Quando um programa é executado na linha de comando, o terminal fica ocupado até que o programa seja concluído. Quando uma aplicação gráfica é executada a partir da linha de comando, a saída de erro do programa, ou STDERR, é enviada para a janela do terminal. Isso pode ser especialmente útil ao solucionar problemas.

Example 1. Visualização de erros iniciando aplicativos gráficos a partir da linha de comando
[fedorauser@localhost]$ astromenace-wrapper
	AstroMenace 1.3.1 121212

	Open XML file: /home/fedorauser/.config/astromenace/amconfig.xml
	VFS file was opened /usr/share/astromenace/gamedata.vfs

	Vendor     : OpenAL Community
	Renderer   : OpenAL Soft
	Version    : 1.1 ALSOFT 1.15.1
	ALut ver   : 1.1

	Font initialized: DATA/FONT/LiberationMono-Bold.ttf

	Current Video Mode: 3200x1080 32bit

	Xinerama/TwinView detected.
	Screen count: 2
	Screen #0: (0, 0) x (1920, 1080)
	Screen #1: (1920, 0) x (1280, 1024)

	Supported resolutions list:
	640x480 16bit
	640x480 32bit
	640x480 0bit
	768x480 16bit
	<output truncated>

To launch a graphical application, but fork the additional output into the background and return the terminal for immediate use, use the shell’s job control feature.

[fedorauser@localhost]$ emacs foo.txt &
Ending a session

Applications that hold the command line prompt until they complete will close when the terminal session ends, even if they are forked into the background.

GUI programs can also be launched on one TTY and displayed on another by specifying the DISPLAY variable. This can be useful when running multiple graphical sessions, or for troubleshooting problems with a desktop session.

  1. Switch to another TTY using the key combination Ctrl+Alt+F2 and log in. Note that consoles are available by default with F2 through F6.

  2. Identify the X session you want to target. The DISPLAY variable is always an integer preceded by a colon, and will be :0 in most cases. Check the arguments of the currently running X process to verify the value. The command below shows both the DISPLAY variable as well as the TTY that X is running on, tty1.

    [fedorauser@localhost]$ ps aux|grep /usr/bin/X
    root      1498  7.1  1.0 521396 353984 tty1    Ss+  00:04  66:34 /usr/bin/X :0 vt1 -background none -nolisten tcp -auth /var/run/kdm/A:0-22Degc
    root     23874  0.0  0.0 109184   900 pts/21   S+   15:35   0:00 grep --color=auto /usr/bin/X
  3. Specify the DISPLAY variable when executing the program.

    [fedorauser@localhost]$ DISPLAY=:0 gnome-shell --replace &
  4. Switch back to the TTY the graphical session is running on. Since the example above shows X running on vt1, pressing Ctrl+Alt+F1 will return to the desktop environment.

Launching Applications with Alt+F2

Most desktop environments follow the convention of using the key combination Alt+F2 for opening new applications. Pressing Alt+F2 brings up a prompt for a command to be entered into.

Commands entered into this dialog box function much as they would if entered in a terminal. Applications are known by their file name, and can accept arguments.

GNOME command entry dialog box
Figure 1. Using Alt+F2 with GNOME
KDE command entry dialog box
Figure 2. Using Alt+F2 with KDE
LXDE command entry dialog box.
Figure 3. Using Alt+F2 with LXDE
MATE command entry dialog box.
Figure 4. Using Alt+F2 with MATE
XFCE command entry dialog box.
Figure 5. Using Alt+F2 with XFCE

Launching applications from the Desktop Menu

Applications can also be opened from the menu system provided by the desktop environment in use. While the presentation may vary between desktop environments, the menu entries and their categories are provided by the individual application and standardized by the freedesktop.org Desktop Menu Specification. Some desktop environments also provide search functionality in their menu system to allow quick and easy access to applications.

Using GNOME menus

The GNOME menu, called the overview, can be accessed by either clicking the Activities button in the top left of the primary display, by moving the mouse past the top left hot corner, or by pressing the Super ( Windows ) key. The overview presents documents in addition to applications.

Selecting an item from the menu is best accomplished using the search box. Simply bring up the overview, and begin typing the name of the application you want to launch. Pressing enter will launch the highlighted application, or you can use the arrow keys or mouse to choose an alternative.

Typing the name of an application into the overview search box will display matching menu entries. The search also matches descriptions
Figure 6. Using the GNOME search box

The overview can also be browsed. The bar on the left, called the dash, shows frequently used applications and a grid icon. Clicking on the grid icon brings up a grid in the center of the window that displays frequently used applications. The grid will display all available applications if selected using the All button at the bottom of the screen.

The GNOME menu has a bar on the left for frequently used applications
Figure 7. Browsing GNOME menu entries

To learn more about using GNOME shell, visit https://wiki.gnome.org/GnomeShell/CheatSheet

Using KDE menus

The KDE menu is opened by clicking the Fedora button at the bottom left corner of the screen. The menu initially displays favorite applications, which can be added to by right clicking any menu entry. Hovering over the icons in the lower portion of the menu will display applications, file systems, recently used applications, or options for logging out of the system.

The KDE menu displays applications in categories. The contents of the categories are displayed when clicked.
Figure 8. The KDE desktop menu.

Search functionality is also available in the KDE menu system. To search for applications, open the menu and begin typing. The menu will display matching entries.

The KDE menu will search for matching applications if you type into the search box. For example
Figure 9. Searching with the KDE menu.

Using menus in LXDE, MATE, and XFCE

Menus in LXDE, MATE, and XFCE have a varied appearance but a very similar structure. They categorize applications, and the contents of a category are displayed by hovering the cursor over the entry. Applications are launched by clicking on an entry.

Figure 10. The LXDE menu
MATE menu
Figure 11. MATE menu
Figure 12. XFCE Menu