Overview of Linux Operating System

OVERVIEW OF LINUX!

Like UNIX, Linux can be generally divided into three major components: the kernel, the environment, and the file structure. The kernel is the core program that runs programs and manages hardware devices, such as disks and printers. The environment provides an interface for the users. It receives commands from the user and sends those commands to the kernel for execution.

An environment acts an interface between the kernel and the user. It can be considered as an interpreter, because it interprets commands entered by the user and sends them to the kernel. Linux provides several kinds of environments: desktops, window managers, and command line shells.

The file structure organizes the way files are stored on a storage device, such as a disk. Files are organized into directories. Each directory may contain any number of sub directories, each holding files. Together, the kernel, the environment, and the file structure form the basic operating system structure. With these three, we can run programs, manage files, and interact with the system.

Advantages of Linux OS:

Linux is a fully functional UNIX OS. It has all the standard features of a powerful UNIX OS, including a complete set of UNIX shells such as bash, tcsh, and the Z shell.  Those familiar with the UNIX interface can use any of these shell, with the same UNIX commands, filters, and configuration features.

For the Internet, Linux has become a platform for very powerful Internet applications. With Linux, we can create our own Web, FTP, and Gopher sites.  Other users can access our Linux system, several at the same time, using different services.

Using Linux, we can control access, set up network connections, and install new devices.  Linux includes very powerful and easy-to-use, window-and Web-based configuration utilities like Lunuxconf and Webmin, which can be used to perform system administrative tasks such as installing printers, adding users, and establishing new network connections.

A wide array of applications operate on Linux.  Many personal versions of commercial applications such as WordPerfect and the Sybase database are available for Linux free of charge.  We can download them directly from the Internet.  Moreover, a massive amount of software is available at online Linux sites where we can down them and install them onto a Linux system.

Types of Linux Environment (UI):

Each user on a Linux system can have his (or her) own user interface.  Users can tailor their environments to their own special needs, whether they be shells, window managers, or desktops.  The shell interface is simple and usually consists of a prompt at which the users type a command, and then press ENTER. Over the years, several different kinds of shells have been developed and, currently, three major shells exist: Bourne, Korn and C shell.  Among these three, the C shell was developed for the BSD version of UNIX.

As an alternative to a command line interface, Linux provides two different versions of GUI - desktop and window manager.  A desktop provides a complete GUI, much like Windows and the MAC.  A window manager, on the other hand, is a reduced version of desktop, supporting only window operation, but it still enables the user to run any application.

In desktop environment, we have desktops, icons, and menus, all managed through mouse controls. Currently, two different desktops are freely available and both are included with most distributions of Linux: Gnome and KDE. With these two desktops - K Desktop Environment (KDE) and GNU Network Object Model Environment (GNOME), Linux now has a completely integrated GUI interface. We can perform all our Linux operations entirely from either interface.

Features of KDE and GNOME:

KDE and GNOME are fully operational desktops supporting drag-and-drop operations, enabling the user to drag icons to the desktop and to set up menus on an Application panel. Both rely on an underlying X Windows system, which means as long as they are both installed on a system, application from one can run on the other desktop.

We can run KDE programs like KDE mailer or the newsreader on the Gnome desktop. Gnome applications like the Gftp - FTP client can run on the KDE desktop.  We can even switch file managers running the KDE file manager on Gnome.  The major difference between these two desktops is that the K desktop has a complete set of Internet tools, along with editors, graphics, multimedia, and system applications, but Gnome has slightly fewer applications.

A great deal of Linux software is currently available from online sources.  We can download applications for desktops, Internet servers, Office suites, programming packages, among others. Software packages are distributed either in compressed archives or in RPM packages.  RPM packages are those archived using the Red Hat Package Manager. Compressed archives have an extension such as .tar.gz or .tar.Z, whereas RPM packages have an .rpm extension.

Samba and Apache:

The name Samba is derived from the Server Message Block protocol or SMB.  SMB is the protocol used by Microsoft OS to share files and printers.  Samba is a suite of programs that implement the SMB protocol on Linux.

Using Samba, we can share machines running Windows 95, Windows 98 or Windows NT with our Linux machine.  Not only files, but also printers managed by Windows OS can be shared with Linux through SMB.

 

Linux OS comes with a web server named Apache.  A Web server enables its users to access resources on a Wide Area Network or the Internet.  It is considered as a process that runs on the OS and enables users to access resources that have been published in the form of web pages.

For example, when the user enters the address of a web site, say www.apache.org, in a web browser, the Apache Web Server sends the home page of the web site to the client machine. Generally, a Web Server is referred to as a computer that delivers web pages.

 

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