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Home , Desktop environment, KDE Display Manager, Xfce

Role Name Affiliation Principal Investigator Dr. Savita Gandhi Professor, Dept. of Computer Science, Gujarat University, Ahmedabad Content Writer Mr. Hardik Joshi Asst. Professor, Dept. of Computer Science, Gujarat University, Ahmedabad Content Reviewer Dr. Hiren Joshi Professor, Dept. of Computer Science, Gujarat University, Ahmedabad

Item Description Subject Name Information Technology Paper Name Open Source Software Module No 5 Module Name Graphical Interface in GNU/ and Basic System Configurations Pre-requisite Knowledge of Objectives To be able to operate the Linux OS using GUI Keywords , GUI, CLI, GNOME, KDE, Display Manager, Session Manager

Graphical Interface in GNU/Linux and Basic System Configurations Overview Usually there are two different interfaces available in all operating systems. These interfaces are Command Line Interface (CLI) and (GUI). Most of the Linux distributions provide CLI and GUI. The hassle in using CLI is that we have to remember which programs and commands are used to perform tasks. Using the GUI is often quick and easy. It allows us to interact with the system through graphical icons and screens. CLI is usually preferred for repetitive tasks or for system administration. Linux provides variety of GUI known as desktop environment. Each desktop environment has peculiar features. The popular desktop environment available in Linux is GNOME, KDE, , LXDE, . GNOME is a widely used desktop environment with an easy to use GUI. GNOME is bundled as the default desktop environment for many distributions, including RHEL, Fedora, CentOS, SUSE Linux Enterprise, and . GNOME has menu- based navigation. KDE is another popular desktop environment, KDE is often used in SUSE and openSUSE. Figures 1,2,3 and figure 4 show different GUI of Linux distributions. Figure 5 illustrates the CLI available in Linux.

Figure 1: Desktop of CentOS

Figure 2: Desktop of

Figure 3: Desktop of Linux

Figure 4: Desktop of

Figure 5: Command Line Interface GUI Startup

In most of the Linux distributions, it is option to install desktop environment, when we install a desktop environment, it comes with . This X display manager starts at the end of the boot . It is responsible for starting the graphics system; the graphics system further provides GUI for logging in the user, and starting the user’s desktop environment. In case, if we have installed multiple desktop environments, we can often select from a choice of desktop environments when logging in to the system.

Display Manager

Display Manage graphical Load X Server Management logins

Display manager is a service that keeps track of the displays being provided. It loads the X server. The X server provides graphical services to different applications (X Clients). In Linux, the display manager works in Client-Server fashion. The display manager also handles desktop functionalities provided to the user after he logs in. The following is a list of popular desktop environments and their corresponding display managers:

GNOME  gdm Ubuntu  KDE  kdm

A desktop environment consists of a session manager, manager and few other utilities. The session manager starts and maintains the components of the graphical session while the controls the placement and movement of windows, window title-bars, and controls.

Desktop Environment

Session Manager Window Manager Utilities

Basic Operations

Linux provides efficient desktop environment through which the users can easily navigate different applications. The desktop environments provide short-cuts to launch applications. The GUI is well designed to easily any application and launch it.

Applications are found at different places in Linux:

 In CentOS, the Applications menu that is available in the upper-left corner of the screen.  In openSUSE, Activities menu found in the upper-left corner of the screen, applications can be opened from the activities menu  In Ubuntu, applications can be opened from the Dash button which is provided in the upper-left corner of the screen.  For KDE, and other environments, a button is provided in the lower-left corner to launch applications.

Submenus

Within the application menus are submenus. They are used for different types of applications which include:  Accessories  Games  Graphics  Internet  Office  Sound and Video  System Tools

Default Applications

There can be multiple applications installed in a system. For instance, there can be more than two browsers like Firefox, Chrome, , etc. When we click on any link or email address, Linux will launch the default application out of multiple apps installed in the system. We can configure the default application for each file type using the file managing program. The file managing program can be used to set the default application to be used for any particular file type.

System Management with GUI

Desktop environments provide menu items to lock screen, switch between users, set time preferences, set system preferences, etc. Figure 6 illustrates the screen from where the desired configurations can be made. Linux also provides a control centre to configure the system. A user can set preferences and can also customize the look and feel of the system. The desktop environment provides control centre through which various customizations can be done. For instance, we can change the desktop background or screen saver, we can configure the network, configure sound, etc. Figure 7 illustrates the control centre available in the GNOME dektop environment.

Figure 6: GNOME System Preferences Menu

Figure 7: Control Centre

Applications in Desktop Environment

Linux desktops provide a wide range of applications that can be launched from the GUI. There are many CLI based applications that can also be used. For instance, there are web browsers that work using CLI. Most of the applications are associated in GUI with the menu and its submenus. For a user, it is very easy to navigate the menu and locate an application. The following table lists few widely used applications available in Linux.

Category Application Name

Web Browser Mozilla Firefox, Chromium, Konqueror, Lynx(CLI)

E-mail Clients Graphical email clients like Thunderbird, Evolution,

Text Mode clients like Mutt, mail

Office Suite Open Office, Libre Office

Integrated Development Eclipse, , , Brackets, etc. Environment (IDE) Internet communications Pidgin, , FileZilla, Hexchat, etc applications

Sound / Media Player , Audacity, Rythmbox, etc.

Video VLC, MPlayer, , Totem, etc.

Multimedia Editing , Cinepaint, Blender, , FFmpeg, etc.

Image processing GIMP, Inkscape, eog, etc.

Let us summarize the key concepts covered in this module • Interfaces available for Linux. • Display Managers • Various tools and applications for communications, office applications, programming, audio/video applications.