1 introduction to linux os

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Introduction to Linux OS


An operating system (OS) is a collection of software that

manages computer hardware resources and provides

common services for computer programs. The operating

system is a vital component of the system software in a

computer system. Application programs usually require an

operating system to function. OS is the interface between

hardware and user .All computers need an OS

OSes are used to run applications and control hardware.

Popular OSes include Windows, Linux, Mac OSX


Linux is a free open-source operating system based on

Unix. Linux was originally created by Linus Torvalds with the

assistance of developers from around the globe. Linux is

free to download, edit and distribute. Linux is a very

powerful operating system and it is gradually becoming

popular throughout the world. Linux is a Unix-like computer

operating system assembled under the model of free and

open source software development and distribution

Linux was originally developed as a free operating system


the underlying source code may be used, modified, and

distributed—commercially or non-commercially—by

anyone under licenses such as the GNU General Public

License. Typically Linux is packaged in a format known

as a Linux distribution for desktop and server use


Before Linux

In 80’s, Microsoft’s DOS was the dominated OS for PC

Apple MAC is better, but expensive

UNIX is much better, but much much expensive. Only

for minicomputer for commercial applications

People was looking for a UNIX based system, which is

cheaper and can run on PC

Both DOS, MAC and UNIX are proprietary, i.e., the

source code of their kernel is protected


GNU project

Established in 1984 by Richard Stallman, who believes

that software should be free from restrictions against

copying or modification in order to make better and

efficient computer programs GNU is a recursive acronym

for “GNU's Not Unix”

Aim at developing a complete Unix-like operating system

which is free for copying and modification Companies

make their money by maintaining and distributing the

software,


e.g. optimally packaging the software with different tools

(Redhat, Slackware, Mandrake, SuSE, etc) 1985,

Stallman started the Free Software Foundation and wrote

the GNU General Public License (GNU GPL) in 1989.

A famous professor Andrew Tanenbaum developed

Minix, a simplified version of UNIX that runs on PC

Minix was for class teaching only. No intention for

commercial use In Sept 1991, Linus Torvalds, a student

of Computer Science at the University of Helsinki,


developed the preliminary kernel of Linux, known as

Linux version 0.01

It was put to the Internet and received enormous

response from worldwide software developers

By March 1992 came version 0.95….. x-windows

It was put to the Internet and received enormous

response from worldwide software developers

By March 1992 came version 0.95….. x-windows


November 1992 SUSE , German version

August 1993 Debian & slackware

March 1994 kernel version 1.0

Oct 1994 Red hat & caldera

March 1996 kernel version 2.0

KDE 1998

Jan 1999 kernel version 2.2

2000 IBM invest 1 Billion$

Jan 2001 kernel version 2.4


Open Office 2002

Late 2003 Fedora

December 2003 kernel version 2.6

October 2004 Ubuntu

July 2011 kernel version 3.0


Linux Pros and Cons

Advantages over Windows

It's almost free to relatively inexpensive. Source code is

included. Bugs are fixed quickly and help is readily

available through the vast support in Internet. Linux is

more stable than Windows. Linux is truly multi-user and

multi-tasking


multiuser: OS that can simultaneously serve a number of

users. multitasking: OS that can simultaneously

execute a number of programs. Linux runs on

equipment that other operating systems consider too

underpowered, e.g. 386 systems, PDA, etc

Disadvantages compared with Windows

Isn't as popular as Windows.Less commercial company

is responsible for Linux.Linux is relatively hard to learn

and use as compared to Windows


Low cost:

There is no need to spend time and huge amount money to

obtain licenses since Linux and much of it’s software come

with the GNU General Public License. There is no need to

worry about any software's that you use in Linux.

Stability:

Linux has high stability compared with other operating

systems. There is no need to reboot the Linux system to

maintain performance levels.


Rarely it freeze up or slow down. It has a continuous up-

times of hundreds of days or more

Performance:

Linux provides high performance on various networks. It

has the ability to handle large numbers of users

simultaneously.

Flexibility:

Linux is very flexible. Linux can be used for high

performance server applications, desktop applications, and

embedded systems.


You can install only the needed components for a particular

use.

Compatibility:

It runs all common Unix software packages and can process

all common file formats.

Wider Choice:

There is a large number of Linux distributions which gives you

a wider choice. Each organization develop and support

different distribution. You can pick the one you like best; the

core function's are the same


Fast and easy installation:

Linux distributions come with user-friendly installation.

Multitasking & Multiuser:

Linux is a multitasking operating system. It can handle

many things at the same time.It is Also a true multiuser OS

Security:

Linux is one of the most secure operating systems. File

ownership and permissions make linux more secure.


Open source:

Linux is an Open source operating systems. You can easily

get the source code for linux and edit it to develop your

personal operating system.


Today, Linux is widely used for both basic home and office

uses. It is the main operating system used for high

performance business and in web servers. Linux has made

a high impact in this world. Today, Linux systems are used

in every domain, from embedded systems to

supercomputers


No threat of viruses

Linux systems are extremely stable

Linux is Free

Linux comes with most of the required software pre-installed

Linux never gets slow

Linux does not need defragmentation

Linux can even run on oldest hardware

Adding more software is a matter of a few clicks

Most Windows-only apps have their either their native version or

alternatives for Linux


Linux distributions

Today there are hundreds of different distributions available

popular Linux distributions include



