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8/6/2019 Topic 1_NOS

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Linux:

Operating system

(Two parts)

kernel

system programs


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GNU/Linux:

GNU => Gnus Not Unix

In general, we use Linux to mean Linux Kernel and GNU/Linux

to mean total operating systems

Gnu: It is Free Software Foundation(FSF) project whose goal is to

build an entirely open source operating system that works likeUNIX.


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GNU/Linux:

GNU project was launched in 1984 by Richard Stallman to develop a

complete UNIX-like operating system

Richard Stallman started this project to make free operating system

but GNU operating system never took off.


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GNU/Linux:

In 1991, Finnish student named Linus Torvalds first developed Linux

in 1991 when he was experimenting with improving MINIX for x86

platform.

MINIX (Mini-UNIX, small educational version of UNIX

developed by Andrew Tannenbaum)

x86 platform was fast becoming standard in homes and businessesacross the world.


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GNU/Linux:

Key Feature of Linux Operating System was that Linus published Linux

underGNU Public License (GPL)

Since 1991, when source code for Linux was released, number of

software developers dedicating to improve Linux increased each year.

Linux Kernel was developed collaboratively and was centrally

managed; however many Linux add-on packages were developed freelyworldwide by members of hacker community who were interested in their

release.


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GNU/Linux:

During early and mid 1990s, Linux development was radical and during

this time, several distributions of Linux appeared

A distribution of Linux used commonly developed Linux Operating

system Kernel and libraries, and it was packaged with add-on software

specific to certain use.


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GNU/Linux:

Many distributions of Linux were formed:

RedHat

Mandrake

SuSE etc.

All distributions of Linux shared a common Kernel and utilities; but

they contain different add-on packages.

Linux Distributions may or may not useGUIs(Graphical User Interface)

Example of Linux that does not contain GUI is that fits on

floppy and can be used as router.

Linux which come with GUIs can be further customized to

suit needs of user


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GNU/Linux:

Core Component ofGUI in Linux is referred to as X Windows

Several Windows Managers and desktop environments are available,

which altogether affect the look and feel ofGUI

These components differ from distribution to distribution.

X Windows in combination with Windows Manager and Desktopenvironment is referred to as GUI Environment.


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GNU/Linux:

Two competingGUI environments are available in Linux:

GNU Network Object Model Environment (GNOME)

K Desktop Environment (KDE)

Both are less comparable in functionality, though users might have

personal preference for one desktop to another.


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GNU/Linux:

GNOME


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GNU/Linux:

KDE


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GNU/Linux:

GNOME is written in C programming language and uses gtk toolkit

KDE is written in C++ programming language and uses qt toolkit

Which language and toolkit best fits the need will be the preferred at

that time.

Most Linux distributions ship with both GNOME and KDE GUIenvironments, whereas others offer support for both to download and

install otherGUI environment.


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GPL:

GPL => GNU Public License

GPL says: You have right to copy, modify and redistribute the code

covered by agreement. If you redistribute code, you must also redistribute

same license with code, making code and license separable.

If source code for Accounting program is downloaded from Internet

that is under GPL, it can be modified and redistributed as executableversion of program. You must also distribute modified source code and

GPL agreement with it.


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Heritage of Linux: UNIX

As a version ofUNIX, history of Linux begins withUNIX.

In late 1960s, effort to develop operating system techniques were

occurred.

In 1968, a consortium of researchers from General electric, AT & T Bell

Labs, and Massachusets Institute of Techology carried out special

operating system research project called MULTICS (MultiplexedInformation and Computing Service). MUTICS incorporated many new

concepts in multitasking, file management, and user interaction.

In 1969, Ken Thompson, Dennis Ritchie, and other researches at AT& T

Bell Laboratories developed Unix Operating system, incorporating many

of the features of MULTICS research project.


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UNIX system became popular at Bell Labs as more and more

researchers started using system.

In 1973, Dennis Ritchie Collaborated with Ken Thompson to rewrite

programming code forUNIX system in C programming language.

UNIX gradually grew from one persons design to standard software

product distributed by different vendors such asNovell and IBM.

Initially, UNIX was research project. So first versions of Unix were

distributed free to computer science departments of many noted

universities.


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Throughout 1970s, Bell Labs began issuing official versions ofUnix

and licensing systems to different users.

One of the users was Computer Science Department ofUniversity of

California, Berkeley. Berkeley added many new features to system and it

became standard.

In 1975, Berkeley released its own version o Unix, known as BerkeleySoftware Distribution(BSD).


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BSD version and AT&T version were biggest contenders.

In 1983, AT & T released its first commercial version ofUNIX called

System 3.

Later, it was followed by System V, which became supported

commercial software product.

At same time, BSD version of UNIX was developing through several

releases.

In late 1970s, BSD Unix became basis of DARPA(Department of

Defenses Advanced ResearchProject Agency)


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In 1983, Berkeley released powerful version ofUNIX called BSD release

4.2.

This release included sophisticated file management as well as

networking features.

BSD release 4.2 was widely distributed and adopted by many vendors

such as Sun Microsystems.

Several other companies such as IBM and HP established Open

Software Foundation(OSF) to create a standard versions ofUnix.

Two commercial versions ofUnix were then existed: OSF version and

System V release 4s


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What is so good about Linux?

Applications : contains tools for graphics, work-processing,

networking, security and administration.

Peripherals : supports wide range of peripherals except

proprietary hardware.

Software : Browsers, mail clients etc

Platforms : All single as well as multiprocessor systems

Emulators : supports programs called emulators that run

code intended for other operating systems.


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Why Linux is popular with Hardware

companies and Developers?

Proprietary Operating Systems

Generic Operating Systems

Linux is Portable

C Programming Language


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Overview of Linux:

Kernel

Shells

Utilities


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Overview of Linux:

Kernel

Shells

Utilities


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Overview of Linux:

Kernel

Multiuser

Multitasking

Hierarchical File System

Links

Security


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Overview of Linux:

Shell

Bourne Again Shell (bash)

TC Shell (tcsh)

Filename Generation

Device independent Input and Output

Shell Functions

Job Control


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Overview of Linux:

Utilities

Inter-process Communication

System Administration


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Additional Features of Linux:

GUIs

Desktop Manager

GNOME

KDE

Window Manager

Inter-networkingUtilities

Software Development

C, C++, Ada, Fortran, Java, Lisp, Pascal, Perl, Python etc.


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References:1) Linux: The Complete Reference by Richard Peterson, Tata McGraw Hill

2) Linux Unleashed by Tim Parker, SAMS Publication

3) A Practical Guide to Linux by Sobell, Pearson Education

4) http://www.iitk.ac.in/LDP/LDP/intro-linux/intro-linux.pdf

5) http://www.computerhope.com/history/unix.htm

6) http://jobsearchtech.about.com/od/techcareersskills/p/Linux.htm7) http://linuxhelp.blogspot.com/2005/11/complete-concise-history-of-gnulinux.html

8) http://digital-domain.net/lug/unix-linux-history.html

9) http://lowfatlinux.com/linux-history.html

10) http://www.wifinotes.com/computer-operating-systems/architecture-of-linux.html

11) http://tldp.org/LDP/gs/node3.html

12) http://blog.friocorte.com/presentation-storage/intro/intro-handout.pdf13) http://i.thiyagaraaj.com/tutorials/linux-overview/linux-architecture

14) http://i.thiyagaraaj.com/tutorials/linux-overview/linux-kernal

15) http://i.thiyagaraaj.com/tutorials/linux-overview/linux-user-interface

16) http://en.wikipedia.org/wiki/Linux_architecture

17) http://www.sics.se/~amir/files/download/os-lab/linux1.pdf

18) http://www.techtinker.com/linux/LinuxArchitecture.html

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