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Chapter 1 Introduction To Linux Linux+ Guide to Linux Certification Second Edition

Chapter 1 Introduction To Linux Linux+ Guide to Linux Certification Second Edition

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Page 1: Chapter 1 Introduction To Linux Linux+ Guide to Linux Certification Second Edition

Chapter 1Introduction To Linux

Linux+ Guide to Linux Certification Second Edition

Page 2: Chapter 1 Introduction To Linux Linux+ Guide to Linux Certification Second Edition

Linux+ Guide to Linux Certification, 2e

2

Objectives Describe the origins of the Linux operating system Understand the term “Opensource Software” Identify the characteristics of various Linux distributions Common uses of Linux in industry today Key features of the Linux operating system

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To understand this diagram – we need to discuss

some history first .

Free Software FoundationAT & T

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What is UNIX It is an operating system which has been commonly used for the past 30 years. It was created in 1969 - long before Microsoft existed. It was the 1st worldwide commercial operating system. Unix has always commonly been used on mainframes. Today it is also commonly being used on PC’s.

Today it runs the global network, commonly called the Internet 80% of the worlds Internet Web servers are using UNIX. The Internet was built on UNIX. TCP/IP is a native UNIX protocol.

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In the beginning …. 1960’s –The American government gave out huge grants to groups willing to do R&D,

using their specifications for the needs of the new computer industry.

1965 – 3 companies AT&T, General Electric & MIT were jointly working on a project to design a new OS called Multics

Which would provide multi-user, multi-tasking, multi-processor functions & would make use of a multi-level (hierarchical) file system

1969 - AT&T was unhappy with the progress.

The development and the relevant costs were all unsatisfactory so they dropped out of the combined project.

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BUT …. The AT&T programmers in the group held onto a copy of Multics. They were Ken Thompson, Dennis Ritchie

They put Multics on an unused mainframe - Digital PDP-7 AND they also renamed it to UNIX.

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1970’s - Unix History & Development

1971 -they developed the 1st UNIX user program

Which was as a text processing tool for the patent department at Bell Labs. the ability for user word processing and formatting.

This 1st real use of UNIX justified further R&D to be supported by AT&T for the UNIX programming group.

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Unix was the first OS to supply: UNIX as an operating system caught on amongst the various industry system

programmers because it was offered them an environment with the following standard features:

1. a simple programmers environment

2. a simple user interface

3. simple utilities or commands that can be combined to perform powerful functions

4. a permanent hierarchical file system

5. simple interface to connect the OS to devices using a consistent file format (device drivers)

6. multi-user functions

7. multi-process system functions

8. which was architecturally independent

9. All of which was permanent and transparent to the user.

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1970’s - Unix History & Development 1972 - Unix was re-written mostly in C, a new programming language

developed by Dennis Ritchie. Being written in this high-level language greatly decreased the effort needed to

port it to new machines.

This made it very easy to run it as a cross platform operating system.

Allowing more sites/programmers to pick it up.

Unix as an OS, had truly started.

1974 - Thompson and Ritchie publish a paper in a Communications magazine describing the new Unix OS. This generated enthusiasm in the Academic community

They saw it’s potential for a great teaching tool for their students who were starting to study programming and systems development.

So AT&T gave it to the universities.

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Thru the late 1970’s – Unix moves into the Uni’s1974 - Berkeley University receives a copy of UNIX from AT&T.

Many other universities also received a copy of UNIX

This uptake of Unix into the universities ensured the further development & popularity of UNIX.

Most universities were now using UNIX to teach their computer science students computer systems & programming.

Each site had it’s own copy of the UNIX source code so they were able to keep developing it and were able to make modifications to the UNIX system they wanted.

Whilst also sharing their code and ideas.

1977 - There are now about 500 Unix sites world-wide.

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Berkeley University creates BSD

1978 - Berkeley University re-wrote most of the existing code and released their own version of UNIX called:

BSD = Berkeley Software Development

Berkeley has also made major enhancements to UNIX which made them a major distribution center for their new version of UNIX.

They have created and added different and new utilities.

The most important being a new network functionality.

Called TCP/IP

1979 - A new small company called Microsoft releases

its own version of unix called Xenix !

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Thru the 1980’s – UNIX went Commercial

Lots of computer companies had used the UNIX source code to develop their own proprietary versions of UNIX.

Which they now sold to run on their own proprietary H/W

So now, many different versions of proprietary unix existed.

AT&T - System V Release 4 Berkeley University - BSD 4.4 Sun - SunOS, Solaris IBM - CPIX , AIX Honeywell - GCOS Hewlett Packard - HP/UX Digital DEC - Ultrix Compaq - VMS, Tru64 Microsoft - Xenix

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Different Proprietary OS’s are run by different vendors on their own CPU.

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As many Unix variations went commercial they also went proprietary and stopped supplying the sourcecode with their version of the UNIX operating system.

NOW - users could no longer view or modify the source code. This locked users into their type of H/W architecture and also gave the vendor

total control over their own proprietary versions of UNIX. Software had started being copyrighted.

1980 – Hobbyist started to make people take the new concept

of micro-processing seriously

1981 – IBM releases a new micro-processing PC running Microsoft DOS

Thru the 1980’s … Proprietary Vendors started controlling the IT industry.

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But some people didn’t agree and still wanted to keep the source code

open and free to all users. Richard Stallman tried to ensure this freedom. He was a systems software developer at MIT and disillusioned with the fragmentation

of UNIX and the industry’s turn to propriety OS systems. So he resigned and started an alternative.

Richard Stallman creating the Free Software Foundation To ensure continued co-operation within the IT industry He started writing his own free OS based on UNIX.

Which he called GNU = ‘GNU’s Not Unix’

He also developed the idea of a “copyleft” software license and started the GPL license.

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The Free Software Foundation FSF – Free Software Foundation

FSF is a non profit organization designed to protect and promote:

freedom for both the user and the IT industry.

The term free software, refers to S/W freedom, not price.

FREEDOM of Distribution NOT Free price

People who put there software under the GPL believe in ‘Free Distribution’ meaning that they believe that the source code for the software cannot be withheld.

It does not mean that they or companies cannot charge for it.

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GPL Software License Software which is placed under the GPL are designed

to give people the right to ….

receive the source code or have the right to get it if you want it.

They can charge for this service if they wish.

And the new user can copy or change the existing software code to suit their needs.

Or even use pieces of it, in any new GPL free programs they design.

But because it originally came from a GPL software they are now obligated to place their new S/W under GPL as well and make their sourcecode available for others.

Software which is put under the GPL Software License is called “Opensource Software”

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Now lets discuss this diagram.

Free Software FoundationAT & T

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Today there are many Software Models

Table 1-2: Software types

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The Opensource Community This is the name given to the group of IT industry members who believe and follow the concepts of the GPL software license and opensource.

Today most of the major IT companies belong to this opensource community.

Companies such as:

Cisco Sun IBM Compaq HP CompTIA Netscape Adobe Oracle etc etc

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The Opensource Community It’s philosophy is based on the FSF philosophy.

They believe in open and distributed computing amongst the IT industry With free IT industry communication in open peer-to-peer exchanges. They believe in open & available sourcecode. They place some or all of their products under the GPL license making them

opensource products. They believe in the combined development & evolution of the IT industry for all.

http://www.opensource.org

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1991 - Welcome to Linux Linux is a clone of UNIX. Created by Linus Torvalds who had used Unix at Uni and wanted it at home but could not

afford the cost of proprietary hardware on which to run a UNIX system.

The PC existed but it was commonly running the Microsoft operating systems and used the Intel chip which did not support commonly unix.

DOS didn’t meet his needs - Linus had developed an interest in minix.

A small very basic UNIX-like system which was compatible with the Intel platform, being used in the universities for teaching.

1991 - So he created one based on minix.

Linus’s Pengin

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The Creation of Linux Linus wrote a full complete version of a unix kernel.

Which he called Linux.

With the assistance of many other developers around the world.

Linus believes in the opensource philosophy

The Linux Kernel is written and distributed under the GPL license

It’s main advantage is it’s - Compatibility for Intel systems.

This meant it could be run on generic PC computer systems.

He chose a Penguin to represent his kernel

Linux is part of the opensource community which believe in the open development & distribution of all sourcecode.

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Understanding Kernel Versions Linux kernel versions are composed of:

Major number Minor number

If odd, referred to as a developmental kernel If even, referred to as a production kernel

Revision number

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The History of Linux is linked to UNIX

Figure 1-4: Timeline of UNIX and Linux development

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History of Linux1990 Richard Stallman had nearly completed his new GNU system

based on the UNIX system. He had most of the modules but was still missing the main part !

The kernel.

Linus Torvalds was developing a new kernel for the Intel architecture based on the UNIX system.

1991 Linus Torvalds put the kernel he was working on out on an internet

FTP server for everyone else’s opinion & help. Linux was released under the GPL license.

Slowly but steadily news of Linux spread and work continued.

1992 Combined with the toolkit of GNU modules & utilities, the Linux kernel had

now become a fully useable operating system. Different distributions of Linux start appearing.

There are now about 1000 Linux Users

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Putting it all into Perspective

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The 1990’s 1993 Internet explosion starts and there’s also an ISP explosion which

cause’s the 1st viable Linux commercial application. The Apache Web Server.

1994 Mark Ewing creates a new distribution called Red Hat

There are now about 500,000 Linux Users

1997 Eric Raymond writes a paper called the ‘Catheral & Baazar’ in which he

analyzes the development & differences of the

‘proprietary’ software model verse the ‘opensource’ software models. The article takes the IT industry by storm.

Eric Raymond becomes the defacto front man for the new opensource movement.

Netscape is the 1st large company to go opensource.

Their director reads the article and in direct response freely releases the source code of the Navigator software.

There are now about 800,000 Linux Users

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The 1990’s1998

Linus, Linux & the opensource movement starts becoming commonly known. And gaining momentum.

Linus appears on TV and on the front of the Forbes Business Magazine. IBM, Oracle, Compaq, SAP + others announce their support for Linux.

There are now about 1.5 million Linux Users

1999 1st Linux World Conference – 6000 people attend Linus delivers the opening and keynote presentation. Red Hat goes public

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The 2000’s 2003

Red Hat splits into 2 versions An enterprise version with which you purchase support And a Home version with no free support

2003 Novell buys SuSE Linux for $210 million Novell also buys Ximian – a desktop Linux software specialist. These purchases dramatically alter the Linux landscape. IBM now the most powerful backer of Linux. To counterbalance the world of Linux they make a 50 million dollar

investment in Novell. SuSE becomes the major competitor to Red Hat.

Red Hat = No 1 Linux distribution SuSE = No 2 Linux distribution

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Linux Today2007

Today Linux has grown from being a hacker / home developed OS to being accepted world wide.

As a commercially viable OS in the IT industry.

It is highly regarded and runs many many major enterprises.

Many sites are now also using it on their client machines.

Linux has gone mainstream !!!

Linux currently has an estimated user figures ranging from 20 to 30 million.

And growing!

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Today MOST proprietary equipment also

uses Linux

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Linux Distributions Remember Linus Torvalds only created the kernel

Many different groups of programmers have all used this kernel and added user functionality to it – then released it as a ‘package’

These different ’packages of LINUX software' are known as distributions.

There are many different distributions of Linux.

Although these distributions often have their own unique flavour they are internally essentially the same – due to the kernel.

In most cases, they are available at no charge via FTP and in other cases they may be purchased on CD for a relatively low cost, or as a companion to a Linux book.

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Table 1-4: Common Linux distributions

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Table 1-4 (continued): Common Linux distributions

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Linux GUI Environments Most distributions ship with a GUI The Core component of this GUI is called X Windows

XWindows is the just the engine on which a desktop manager runs and supplies the GUI desktop.

The GUI environment is created by X Windows in combination with a window manager and desktop environment

There are 2 primary competing GUI environments in Linux: GNU Object Model Environment (GNOME) Kommon Desktop Environment (KDE) All the GUIs’ can be customized to suit needs of the user

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GNOME Desktop

Figure 1-2: A Linux graphical user interface

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Figure 1-5: The GNOME Desktop

Fedora using GNOME

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Linux is also currently being used by many companies as their Office Workstation With software designed for end users in office and home environments

Office productivity suites

Writer word processing Calc spreadsheets Impress slide show Base database

Graphics editing software Desktop publishing software Financial software Games All available as opensource applications.

See http://sourceforge.net for lots of opensource software

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Linux is also currently being used to provide many common Networking Server Services.

AND They are all inbuilt into the kernel

Mail Web Proxy DNS DHCP FTP Firewall File sharing Network Printing

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Ease of Obtaining Support

Lots & Lots of Linux documentation can be found on the Internet HOWTO documents Frequently Asked Questions (FAQs)

Lots of Linux Forums & Newsgroups on the Internet

Linux User Group (LUG): Open forum of Linux users who meet to discuss &assist each other in using and modifying the Linux OS

SLUG – Sydney Linux User Group

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Linux Tomorrow!

USA regularly holds government conferences with the opensource community.

to discuss the impact that the opensource community has on the global use of future IT.

All the major opensource IT companies are involved

First - Microsoft chose to ignore opensource.

But now Microsoft attends the conferences.

Microsoft also now has regular stands at the Linux Trade Shows

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