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Chapter 1
Introduction To Linux
Linux+ Guide to Linux Certification
Second Edition
Objectives
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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 .
AT & T
Free Software Foundation
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What is UNIX
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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 ….
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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.
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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
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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.
BUT …. The AT&T programmers in the group held onto a copy of
Multics. They were Ken Thompson, Dennis Ritchie
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They put Multics on an unused mainframe - Digital PDP-7
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AND they also renamed it to UNIX.
1970’s - Unix History & Development
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1971 -they developed the 1st UNIX user program
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Which was as a text processing tool for the patent department at Bell Labs.
the ability for user word processing and formatting.
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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:
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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.
2.
3.
4.
5.
6.
7.
8.
9.
a simple programmers environment
a simple user interface
simple utilities or commands that can be combined to perform powerful functions
a permanent hierarchical file system
simple interface to connect the OS to devices using a consistent file format
(device drivers)
multi-user functions
multi-process system functions
which was architecturally independent
All of which was permanent and transparent to the user.
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1970’s - Unix History & Development
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1972 - Unix was re-written mostly in C, a new programming language
developed by Dennis Ritchie.
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Being written in this high-level language greatly decreased the effort needed to
port it to new machines.
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This made it very easy to run it as a cross platform operating system.
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Allowing more sites/programmers to pick it up.
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Unix as an OS, had truly started.
1974 - Thompson and Ritchie publish a paper in a Communications
magazine describing the new Unix OS.
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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.
Thru the late 1970’s – Unix moves into the Uni’s
1974 - Berkeley University receives a copy of UNIX from AT&T.
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Many other universities also received a copy of UNIX
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This uptake of Unix into the universities ensured the further
development & popularity of UNIX.
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Most universities were now using UNIX to teach their computer science
students computer systems & programming.
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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.
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Whilst also sharing their code and ideas.
1977 - There are now about 500 Unix sites world-wide.
Berkeley University creates BSD
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1978 - Berkeley University re-wrote most of the existing code and
released their own version of UNIX called:
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BSD = Berkeley Software Development
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Berkeley has also made major enhancements to UNIX which made them
a major distribution center for their new version of UNIX.
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They have created and added different and new utilities.
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The most important being a new network functionality.
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1979 -
Called TCP/IP
A new small company called Microsoft releases
its own version of unix called Xenix !
Thru the 1980’s – UNIX went Commercial
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Lots of computer companies had used the UNIX source code to develop
their own proprietary versions of UNIX.
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Which they now sold to run on their own proprietary H/W
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So now, many different versions of proprietary unix existed.
AT&T
Berkeley University
Sun
IBM
Honeywell
Hewlett Packard
Digital DEC
Compaq
Microsoft
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System V Release 4
BSD 4.4
SunOS, Solaris
CPIX , AIX
GCOS
HP/UX
Ultrix
VMS, Tru64
Xenix
Different Proprietary OS’s are run by
different vendors on their own CPU.
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Thru the 1980’s …
Proprietary Vendors started controlling the IT industry.
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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.
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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
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1981 – IBM releases a new micro-processing PC running Microsoft DOS
But some people didn’t agree and still wanted to keep
the source code open and free to all users.
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Richard Stallman tried to ensure this freedom.
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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.
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Richard Stallman creating the Free Software Foundation
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To ensure continued co-operation within the IT industry
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He started writing his own free OS based on UNIX.
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Which he called GNU = ‘GNU’s Not Unix’
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He also developed the idea of a “copyleft” software license and started the GPL license.
The Free Software Foundation
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FSF – Free Software Foundation
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FSF is a non profit organization designed to protect and promote:
freedom for both the user and the IT industry.
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The term free software, refers to S/W freedom, not price.
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FREEDOM of Distribution NOT Free price
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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.
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It does not mean that they or companies cannot charge for it.
GPL Software License
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Software which is placed under the GPL are designed
to give people the right to ….
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receive the source code or have the right to get it if you want it.
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They can charge for this service if they wish.
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And the new user can copy or change the existing software code to
suit their needs.
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Or even use pieces of it, in any new GPL free programs they design.
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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”
Now lets discuss this diagram.
AT & T
Free Software Foundation
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Today there are many Software Models
Table 1-2: Software types
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The Opensource Community
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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.
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Today most of the major IT companies belong to this opensource community.
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Companies such as:
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Cisco Sun IBM Compaq HP CompTIA
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Netscape Adobe Oracle etc etc
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The Opensource Community
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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.
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http://www.opensource.org
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1991 - Welcome to Linux
Linus’s Pengin
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Linux is a clone of UNIX.
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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.
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The PC existed but it was commonly running the Microsoft operating systems
and used the Intel chip which did not support commonly unix.
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DOS didn’t meet his needs - Linus had developed an interest in minix.
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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.
The Creation of Linux
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Linus wrote a full complete version of a unix kernel.
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Which he called Linux.
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With the assistance of many other developers around the world.
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Linus believes in the opensource philosophy
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The Linux Kernel is written and distributed under the GPL license
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It’s main advantage is it’s - Compatibility for Intel systems.
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This meant it could be run on generic PC computer systems.
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He chose a Penguin to represent his kernel
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Linux is part of the opensource community which believe in the open development
& distribution of all sourcecode.
Understanding Kernel Versions
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Linux kernel versions are composed of:
 Major number
 Minor number
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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 Linux
1990 Richard Stallman had nearly completed his new GNU system
based on the UNIX system.
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He had most of the modules but was still missing the main part !
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The kernel.
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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.
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Linux was released under the GPL license.
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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.
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Different distributions of Linux start appearing.
There are now about 1000 Linux Users
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.
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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.
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The article takes the IT industry by storm.
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Eric Raymond becomes the defacto front man for the new opensource movement.
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Netscape is the 1st large company to go opensource.
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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
The 1990’s
1998
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Linus, Linux & the opensource movement starts becoming commonly known.
And gaining momentum.
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Linus appears on TV and on the front of the Forbes Business Magazine.
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IBM, Oracle, Compaq, SAP + others announce their support for Linux.
There are now about 1.5 million Linux Users
1999
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1st Linux World Conference – 6000 people attend
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Linus delivers the opening and keynote presentation.
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Red Hat goes public
The 2000’s
2003
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Red Hat splits into 2 versions
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An enterprise version with which you purchase support
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And a Home version with no free support
2003
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Novell buys SuSE Linux for $210 million
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Novell also buys Ximian – a desktop Linux software specialist.
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These purchases dramatically alter the Linux landscape.
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IBM now the most powerful backer of Linux.
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To counterbalance the world of Linux they make a 50 million dollar
investment in Novell.
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SuSE becomes the major competitor to Red Hat.
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Red Hat = No 1 Linux distribution
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SuSE
= No 2 Linux distribution
Linux Today
2007
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Today Linux has grown from being a hacker / home developed OS
being accepted world wide.
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As a commercially viable OS in the IT industry.
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It is highly regarded and runs many many major enterprises.
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Many sites are now also using it on their client machines.
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Linux has gone mainstream !!!
Linux currently has an estimated user figures ranging
from 20 to 30 million.
And growing!
Today MOST proprietary equipment also uses Linux
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Linux Distributions
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Remember Linus Torvalds only created the kernel
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Many different groups of programmers have all used this kernel and added user
functionality to it – then released it as a ‘package’
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These different ’packages of LINUX software' are known as distributions.
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There are many different distributions of Linux.
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Although these distributions often have their own unique flavour they are internally
essentially the same – due to the kernel.
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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.
Table 1-4: Common Linux distributions
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Table 1-4 (continued): Common Linux distributions
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Linux GUI Environments
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Most distributions ship with a GUI
The Core component of this GUI is called X Windows
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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:
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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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Fedora using GNOME
Figure 1-5: The GNOME Desktop
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Linux is also currently being used by many
companies as their Office Workstation
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With software designed for end users in office and home environments
 Office productivity suites
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Writer
Calc
Impress
Base
word processing
spreadsheets
slide show
database
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Graphics editing software
Desktop publishing software
Financial software
Games
All available as opensource applications.
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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.
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AND They are all inbuilt into the kernel
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Mail
Web
Proxy
DNS
DHCP
FTP
Firewall
File sharing
Network Printing
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Ease of Obtaining Support
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Lots & Lots of Linux documentation can be found on the Internet
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HOWTO documents
Frequently Asked Questions (FAQs)
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Lots of Linux Forums & Newsgroups on the Internet
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Linux User Group (LUG): Open forum of Linux users who meet
t
discuss &assist each other in using and modifying the Linux OS
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SLUG – Sydney Linux User Group
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Linux Tomorrow!
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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.
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All the major opensource IT companies are involved
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First - Microsoft chose to ignore opensource.
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But now Microsoft attends the conferences.
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Microsoft also now has regular stands at the Linux Trade Shows