O.S.Lab Experiment 1

Introduction to LINUX

In 1980`s and 90`s, people had to choose between inexpensive, market driven PC operating system from Microsoft and expensive technology driven operating system such as UNIX. At that time, there was a need of a common platform and a free software was being created all over the world known as LINUX.

Red Hat LINUX is the most popular commercial distribution of LINUX. Red Hat LINUX distribution includes 2 desktop environments known as KDE and Gnome.

LINUX also has certain graphical administrative tools to simplify administrative tasks.

LINUX offers the same icons and menus to help standardize your system just similar to windows.

Features of LINUX help you to :-

• To connect your computer to LAN or Internet.
• Create documents and publish your work on paper.
• Work with multimedia content to manipulate images, view, ideas and even burn your own CD`s.
• Play games individually or over a network.
• Configure a computer to act as a print server, web server, file server, etc.

What is LINUX ?

LINUX is a free operating system that was created by Linus Torvalds when he was a second year student of computer science at university of Helsinki in Finland in 1991.

Torvalds started LINUX by creating a Kernel (heart of OS). Torvalds then released the system to his friends on Internet and asked them to work on it and enhance it. Today there are hundreds of software developers contributing software to Linus`s efforts. Since the source code of the software is freely available anyone can work on it, use it and change it.

Hardware Requirements for LINUX :-

To run LINUX on a system, following are the basic requirements to be fulfilled in terms of processing power, memory size and disk space. We need 16-bit microprocessor and

3 MB of RAM. The hard disk should be 80 MB or more.

Features of LINUX :-

Every kernel of LINUX offers following features :-

1. Multi-user: Not only you can have many accounts available on LINUX, you can also have multi-users logged in and working on the system at a time users can even have their environments arranged the way they want i.e. they can have their own desktop interface with icons, menus and applications arranged to suit them. Users accounts can be password protected so that user can control application and data access.

2. Multi-tasking: In LINUX, it is possible to have many programs running at the same time which means not only you can have many programs going at once but that LINUX operating system have programs running at the backgrounds(daemons).

3. GUI (X-Windows system): The powerful framework for working with graphical applications with LINUX is referred to as X-Windows system. It provides you the look and feel of GUI icons, menus, colors, etc.

4. Hardware Support: LINUX can configure support for any system network that can be connected to a computer.

5. Networking Connectivity: To connect LINUX to a network, LINUX offers support for variety of LAN boards, modems and serial devices.

6. Network Server: LINUX provides network services to client computers on LAN or entire Internet. A variety of software packages are available that enable LINUX to be used as print server, mail server, ftp server, etc.

The best assets of LINUX are its price and reliability. The initial price of LINUX is free and its reliability is compared to UNIX and is more reliable than desktop oriented system.

Other advantage is its availability on Internet and if u need something fixed, you can patch the codes yourself.

7. System Security: There are three levels of security.

· First Level: First level of security is called system security.

This ensures that not just anybody can start running LINUX on your system without a login session.

· Second Level: Second level is incorporated to LINUX when

it comes to accessing files.

· Third Level: Third level allows you to encrypt data files on

disk that even if someone manages to access

one, he cannot make much sense of it.

Structure of LINUX :-

Kernel :-

LINUX Kernel is core of system. It controls all the task schedules of all processes and it carries out all crucial functions of OS. Among major duties of Kernel is to keep track of programs that are executed, allot processor time to each and decide when one program starts and other stops. The Kernel handles information exchange between computers and its resources.

Shell :-

It is command interpreter of OS. It accepts commands from user, interprets user commands and starts appropriate executable file. It then requests Kernel to carry out the actual transfer of data which finally leads to the output displayed on the terminal.

There are three shells :-

1. B shell (Bourne shell).
2. C shell.
3. K shell (Korn shell).