Opening Graphical Applications

Opening graphical applications from the command line

Graphical applications can be launched from a terminal window or console session by simply typing the name of the application.

[fedorauser@localhost]$ firefox

When a program is executed on the command line, the terminal is occupied until the program completes. When a graphical application is executed from the command line, the program’s error output, or STDERR, is sent to the terminal window. This can be especially useful when troubleshooting.

Example 1. Viewing errors by launching graphical applications from the command line

[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 &

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.

Figure 1. Using Alt+F2 with GNOME

Figure 2. Using Alt+F2 with KDE

Figure 3. Using Alt+F2 with LXDE

Figure 4. Using Alt+F2 with MATE

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.

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.

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.

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.

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

Figure 11. MATE menu

Figure 12. XFCE Menu