Every time you switch on your computer, you see a screen where you can perform different activities like write, browse the internet or watch a video. What is it that makes the computer hardware work like that? How does the processor on your computer know that you are asking it to run a mp3 file? Well, it is the operating system or the kernel which does this work. A kernel is a program at the heart of any operating system that takes care of fundamental stuff, like letting hardware communicate with software. So, to work on your computer you need an operating system (OS). In fact, you are using one as you read on your computer. Now, you may have used popular OS’s like Windows, Apple OS X but here we see what Linux is and what benefits it offers over other OS choices.

1. INTRODUCTION TO LINUX
Ankita Tiwari
M.Tech (EST)-1st Year
Amity School of Engineering and Technology
Amity University Lucknow
23-Aug-2016

2. i
Summary
Every time you switch on your computer, you see a screen where you can perform different
activities like write, browse the internet or watch a video. What is it that makes the computer
hardware work like that? How does the processor on your computer know that you are asking it to
run a mp3 file?
Well, it is the operating system or the kernel which does this work. A kernel is a program at the
heart of any operating system that takes care of fundamental stuff, like letting hardware
communicate with software.
So, to work on your computer you need an operating system (OS). In fact, you are using one as you
read on your computer. Now, you may have used popular OS’s like Windows, Apple OS X but
here we see what Linux is and what benefits it offers over other OS choices.

3. ii
Table of Contents
Summary i
Introduction 1
Classification of Operating Systems X
Multi-user X
Multiprocessing X
Multitasking X
Multithreading
Real time
What is LINUX X
Technical terms used in Linux X
Some examples of desktop environments X
Applications X
History X
Conclusions X
References X

4. 1
Introduction
The operating system (OS) is the most important program that runs on a computer. Every general-
purpose computer must have an operating system to run other programs and applications.
Computer operating system performs basic tasks, such as recognizing input from the keyboard,
sending output to the display screen, keeping track of files and directories on the disk and
controlling peripheral devices such as printers.
For large systems operating system has even greater responsibilities and powers. It is like a traffic
cop—it makes sure that different programs and users running at the same time do not interfere with
each other. The operating system is also responsible for security, ensuring that unauthorized user
do not access the system.
Classification of Operating Systems
Multi-user
Allows two or more users to run programs at the same time. Some operating systems permit
hundreds or even thousands of concurrent users.
Multiprocessing
Supports running a program on more than one CPU.
Multitasking
Allows more than one program to run concurrently.
Multithreading
Allows different parts of a single program to run concurrently.
Real time
Responds to input instantly. General-purpose operating systems, such as DOS and UNIX are
not real time.

5. 2
What is Linux?
Just like Windows7, Windows8, UNIX, Mac OS X, Linux is an Operating System.
Linux is a Unix-like and mostly POSIX-complaint computer operating system (OS)
assembled under the model of free and open-source software development and distribution. The
defining component of Linux kernel, an operating system kernel first released on October 5,1991by
Linus Torvalds. The free Software Foundation uses the name GNU/Linux to describe the operating
system, which has led to some controversy.
Linux was originally developed as a free operating system for personal computers based on the
Intel x86 architecture, but has since been ported to more computer hardware platforms than any
other operating system. Because of the dominance of Android on smart phones, Linux has the
largest installed base of all general-purpose operating systems. Linux is also the leading operating
system on servers and other big iron system such as mainframe computers and virtually all fastest
supercomputers.
Linux also runs on embedded systems, which are devices whose operating system is typically built
into the firmware and is highly tailored to the system; this include smart phones and tablet
computers running Android and other Linux derivatives, TiVo and similar DVR devices, network
routers, facility automation controls, televisions, video games consoles and smart watches.
The development of Linux is one of the most prominent examples of free and open-source software
collaboration. The underlying source code may be used, modified and distributed-commercially or
non-commercially-by anyone under the terms of its respective licenses, such as the GPU General
Public License. Typically, Linux is packaged in a form known as Linux distribution (for distro for
short) for both desktop and server use. Some of the most popular mainstream Linux distributions
are Arch Linux, CentOS, Debian, Fedora,Gentoo Linux, Linux Mint Mageia, openSUSE and
Ubuntu, together with commercial distributions such as Red Hat Enterprise Linux and SUSE Linux
Enterprise Server. Distributions include the Linux kernel, supporting utilities and libraries, many of
which are provided by the GNU Project, and usually a large amount of application software to
fulfil the distribution’s intended use.
Technical term used to Linux
The Bootloader
The software that manages the boot process of your computer. For most users, this will simply be a
splash screen that pops up and eventually goes away to boot into the operating system.

6. 3
The Kernel
This is the one piece of the whole that is actually called “Linux”. The kernel is the core of the
system and manages the CPU, memory, and peripheral devices. The kernel is the “lowest” level of
the OS.
Daemons
These are background services (printing, sound, scheduling, etc.) that either start up during boot, or
after you log into the desktop.
The Shell
It is a user program or it's environment provided for user interaction. Shell is an command
language interpreter that executes commands read from the standard input device (keyboard) or
from a file. Shell is not part of system kernel, but uses the system kernel to execute programs,
create files etc.
Desktop Environment
This is the piece of the puzzle that the users actually interact with. There are many desktop
environments to choose from (Unity, GNOME, Cinnamon, Enlightenment, KDE, XFCE, etc)

7. 4
Some examples of desktop environment
GNOME
Unity

8. 5
KDE
Cinnamon

9. 6
Applications
• Just like Windows and Mac, Linux offers thousands upon thousands of high-quality
software titles that can be easily found and installed
• Include App Store-like tools that centralize and simplify application installation. For
example: Ubuntu Linux has the Ubuntu Software Center which allows you to quickly
search among the thousands of apps and install them from one centralized location.

10. 7
History
Some histories of Linux begin with this message posted by Linus Torvalds to the
comp.os.minix newsgroup on August 25, 1991 (http://groups.google.com
/group/comp.os.minix/msg/b813d52cbc5a044b?pli=1):
Minix was a UNIX-like operating system that ran on PCs in the early 1990s. Like Minix,
Linux was also a clone of the UNIX operating system. With few exceptions, such as
Microsoft Windows, most modern computer systems (including Mac OS X and Linux)
were derived from UNIX operating systems, created originally by AT&T.
To truly appreciate how a free operating system could have been modeled after a proprietary
system from AT&T Bell Laboratories, it helps to understand the culture in which UNIX was
created and the chain of events that made the essence of UNIX possible to reproduce freely.
GNU transitions UNIX to freedom
In 1984, Richard M. Stallman started the GNU project,
recursively named by the phrase GNU is Not UNIX. As a project of the Free Software
Foundation (FSF), GNU was intended to become a recording of the entire UNIX operating
system that could be freely distributed.
The GNU Project page (http://www.gnu.org/gnu/thegnuproject.html) tells the
story of how the project came about in Stallman’s own words. It also lays out the problems
that proprietary software companies were imposing on those software developers
who wanted to share, create, and innovate.
Although rewriting millions of lines of code might seem daunting for one or two people,
spreading the effort across dozens or even hundreds of programmers made the project
possible. Remember that UNIX was designed to be built in separate pieces that could be
piped together. Because they were reproducing commands and utilities with well-known
interfaces, that effort could easily be split among many developers.
It turned out that not only could the same results be gained by all new code, but in some
cases, that code was better than the original UNIX versions. Because everyone could see
the code being produced for the project, poorly written code could be corrected quickly
or replaced over time.
Over time, the term free software has been mostly replaced by the term open source
Linus Benedict Torvalds
Hello everybody out there using minix -
I’m doing a (free) operating system(just a hobby, won’t be big and professional
like gnu) for 386(486) AT clones. This has been brewing since april, and is
starting to get ready. I’d like any feedback on things people like/dislike in
minix, as my OS resembles it somewhat (same physical layout of the filesystem
(due to practical reasons, among other things) . . . Any suggestions are
welcome, but I won’t promise I’ll implement them :-)
Linus (torvalds@kruuna.helsinki.fi )
PS. Yes — it’s free of any minix code, and it has a multi-threaded fs. It is NOT
protable[sic] (uses 386 task switching etc), and it probably never will support
anything other than AT-harddisks, as that’s all I have :-(.

11. 8
software. The term “free software” is preferred by the Free Software Foundation,
while open source software is promoted by the Open Source Initiative
(http://www.opensource.org).
To accommodate both camps, some people use the term Free and Open Source Software
(FOSS) instead. An underlying principle of FOSS, however, is that, although you are free
to use the software as you like, you have some responsibility to make the improvements
you make to the code available to others. In that way, everyone in the community can
benefi t from your work as you have benefi ted from the work of others.
To clearly defi ne how open source software should be handled, the GNU software project
created the GNU Public License, or GPL. Although many other software licenses
cover slightly different approaches to protecting free software, the GPL is the most well
known — and it’s the one that covers the Linux kernel itself. Basic features of the GNU
Public License include the following:
■ Author rights — The original author retains the rights to his or her software.
■ Free distribution — People can use the GNU software in their own software,
changing and redistributing it as they please. They do, however, have to include
the source code with their distribution (or make it easily available).
■ Copyright maintained — Even if you were to repackage and resell the software,
the original GNU agreement must be maintained with the software, which
means all future recipients of the software have the opportunity to change the
source code, just as you did.
There is no warranty on GNU software. If something goes wrong, the original developer
of the software has no obligation to fi x the problem. However, many organizations, big
and small, offer paid support packages for the software when it is included in their Linux
or other open source software distribution. (See the “OSI open source definition” section
later in this chapter for a more detailed definition of open source software.)
Despite its success in producing thousands of UNIX utilities, the GNU project itself failed
to produce one critical piece of code: the kernel. Its attempts to build an open source
kernel with the GNU Hurd project (http://www.gnu.org/software/hurd) were unsuccessful.
OSI open source definition
Linux provides a platform that lets software developers change the operating system
as they like and get a wide range of help creating the applications they need. One of
the watchdogs of the open source movement is the Open Source Initiative (OSI,
http://www.opensource.org).
Although the primary goal of open source software is to make source code available,
other goals of open source software are also defined by OSI in its open source definition.
Most of the following rules for acceptable open source licenses serve to protect the freedom
and integrity of the open source code:
■ Free distribution — an open source license can’t require a fee from anyone who
resells the software.
■ Source code — The source code must be included with the software and there
can be no restrictions on redistribution.
■ Derived works — The license must allow modifi cation and redistribution of the
code under the same terms.

12. 9
■ Integrity of the author’s source code — The license may require that those who
use the source code remove the original project’s name or version if they change
the source code.
■ No discrimination against persons or groups — The license must allow all people
to be equally eligible to use the source code.
■ No discrimination against fields of endeavor — The license can’t restrict a
project from using the source code because it is commercial or because it is associated
with a fi eld of endeavor that the software provider doesn’t like.
■ Distribution of license — No additional license should be needed to use and
redistribute the software.

13. 10
Conclusions
Linux gets its due attention
The main advantage of Linux was that programmers were able to use the Linux Kernel in order to
design their own custom operating systems. With time, a new range of user-friendly OS's stormed
the computer world. Now, Linux is one of most popular and widely used Kernel, and it is the
backbone of popular operating systems like Debian, Knoppix, Ubuntu, and Fedora. Nevertheless,
the list does not end here as there are thousands of OS's based on Linux which offer a variety of
functions to the users.
The benefits of using Linux
Linux now enjoys popularity at its prime and it's famous among programmers as well as regular
computer users around the world. Its main benefits are -
It offers a free operating system. You do not have to shell hundreds of dollars to get the OS like
Windows!
 Being open-source, anyone with programming knowledge can modify it.
 The Linux operating systems now offer millions of programs/applications to choose from,
most of them free!
 Once you have Linux installed you no longer need an antivirus! Linux is a highly secure
system. More so , there is a global development community constantly looking at ways to
enhance its security. With each upgrade, the OS becomes more secure and robust
 Linux is the OS of choice for Server environments due to its stability and reliability (Mega-
companies like Amazon, Face book, and Google use Linux for their Servers). A Linux
based server could run non-stop without a reboot for years on end.

14. 11
Is it for me?
Users, who are new to Linux, usually shun it by falsely considering it as a difficult and technical
OS to operate but, to state the truth, in the last few years Linux operating systems have become a
lot more user-friendly than their counterparts like Windows, so trying them is the best way to know
whether Linux suits you or not.
There are thousands of Linux based operating systems; most of them offer state-of-the-art security
and applications, all of it for free!
This is what Linux is all about, and now we will move on to how to install Linux and which
Distribution you should choose.

15. 12
References
www.wikipedia.com
www.google.com
www.webopedia.com
www.guru99.com
Linux-Bible (Christopher-Negus)