Introduction Of Linux

Introduction Of Linux

We will start with an overview of how Linux became the operating system it is today. We
will discuss past and future development and take a closer look at the advantages and
disadvantages of this system. We will talk about distributions, about Open Source in general
and try to explain a little something about GNU.


This chapter answers questions like:
♦ What is Linux?
♦ Where and how did Linux start?
♦ Isn't Linux that system where everything is done in text mode?
♦ Does Linux have a future or is it just hype?
♦ What are the advantages of using Linux?
♦ What are the disadvantages?
♦ What kinds of Linux are there and how do I choose the one that fits me?
♦ What are the Open Source and GNU movements?

1.1. History
1.1.1. UNIX
In order to understand the popularity of Linux, we need to travel back in time, about 30 years ago...
Imagine computers as big as houses, even stadiums. While the sizes of those computers posed substantial
problems, there was one thing that made this even worse: every computer had a different operating system.
Software was always customized to serve a specific purpose, and software for one given system didn't run on
another system. Being able to work with one system didn't automatically mean that you could work with
another. It was difficult, both for the users and the system administrators.
Computers were extremely expensive then, and sacrifices had to be made even after the original purchase just
to get the users to understand how they worked. The total cost per unit of computing power was enormous.
Technologically the world was not quite that advanced, so they had to live with the size for another decade. In
1969, a team of developers in the Bell Labs laboratories started working on a solution for the software
problem, to address these compatibility issues. They developed a new operating system, which was
1. Simple and elegant.
2. Written in the C programming language instead of in assembly code.
3. Able to recycle code.
The Bell Labs developers named their project "UNIX."

The code recycling features were very important. Until then, all commercially available computer systems

were written in a code specifically developed for one system. UNIX on the other hand needed only a small

piece of that special code, which is now commonly named the kernel. This kernel is the only piece of code

that needs to be adapted for every specific system and forms the base of the UNIX system. The operating

system and all other functions were built around this kernel and written in a higher programming language, C.This language was especially developed for creating the UNIX system. Using this new technique, it was much easier to develop an operating system that could run on many different types of hardware.

The software vendors were quick to adapt, since they could sell ten times more software almost effortlessly.

Weird new situations came in existence: imagine for instance computers from different vendors

communicating in the same network, or users working on different systems without the need for extra

education to use another computer. UNIX did a great deal to help users become compatible with different

systems.

Throughout the next couple of decades the development of UNIX continued. More things became possible to do and more hardware and software vendors added support for UNIX to their products.
UNIX was initially found only in very large environments with mainframes and minicomputers (note that a
PC is a "micro" computer). You had to work at a university, for the government or for large financial
corporations in order to get your hands on a UNIX system.
But smaller computers were being developed, and by the end of the 80's, many people had home computers.
By that time, there were several versions of UNIX available for the PC architecture, but none of them were
truly free and more important: they were all terribly slow, so most people ran MS DOS or Windows 3.1 on
their home PCs.
1.1.2. Linus and Linux
By the beginning of the 90s home PCs were finally powerful enough to run a full blown UNIX. Linus
Torvalds, a young man studying computer science at the university of Helsinki, thought it would be a good
idea to have some sort of freely available academic version of UNIX, and promptly started to code.
He started to ask questions, looking for answers and solutions that would help him get UNIX on his PC.
Below is one of his first posts in comp.os.minix, dating from 1991:
From: torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds)
Newsgroups: comp.os.minix
Subject: Gcc-1.40 and a posix-question
Message-ID: <1991Jul3.100050.9886@klaava.Helsinki.FI>
Date: 3 Jul 91 10:00:50 GMT
Hello netlanders,

Due to a project I'm working on (in minix), I'm interested in the posix

standard definition. Could somebody please point me to a (preferably)

machine-readable format of the latest posix rules? Ftp-sites would be

nice.

From the start, it was Linus' goal to have a free system that was completely compliant with the original UNIX.
That is why he asked for POSIX standards, POSIX still being the standard for UNIX.
In those days plug-and-play wasn't invented yet, but so many people were interested in having a UNIX system of their own, that this was only a small obstacle. New drivers became available for all kinds of new hardware, at a continuously rising speed. Almost as soon as a new piece of hardware became available, someone bought it and submitted it to the Linux test, as the system was gradually being called, releasing more free code for an ever wider range of hardware. These coders didn't stop at their PC's; every piece of hardware they could find was useful for Linux. 
Back then, those people were called "nerds" or "freaks", but it didn't matter to them, as long as the supported hardware list grew longer and longer. Thanks to these people, Linux is now not only ideal to run on new PC's, 


Two years after Linus' post, there were 12000 Linux users. The project, popular with hobbyists, grew steadily,
all the while staying within the bounds of the POSIX standard. All the features of UNIX were added over the
next couple of years, resulting in the mature operating system Linux has become today. Linux is a full UNIX
clone, fit for use on workstations as well as on middle-range and high-end servers. Today, a lot of the
important players on the hard- and software market each have their team of Linux developers; at your local
dealer's you can even buy pre-installed Linux systems with official support - eventhough there is still a lot of
hard- and software that is not supported, too.
1.1.3. Current application of Linux systems
Today Linux has joined the desktop market. Linux developers concentrated on networking and services in the beginning, and office applications have been the last barrier to be taken down. We don't like to admit that
Microsoft is ruling this market, so plenty of alternatives have been started over the last couple of years to
make Linux an acceptable choice as a workstation, providing an easy user interface and MS compatible office applications like word processors, spreadsheets, presentations and the like.
On the server side, Linux is well-known as a stable and reliable platform, providing database and trading
services for companies like Amazon, the well-known online bookshop, US Post Office, the German army and many others. Especially Internet providers and Internet service providers have grown fond of Linux as
firewall, proxy- and web server, and you will find a Linux box within reach of every UNIX system
administrator who appreciates a comfortable management station. Clusters of Linux machines are used in the
creation of movies such as "Titanic", "Shrek" and others. In post offices, they are the nerve centers that route
mail and in large search engine, clusters are used to perform internet searches.These are only a few of the
thousands of heavy-duty jobs that Linux is performing day-to-day across the world.
It is also worth to note that modern Linux not only runs on workstations, mid- and high-end servers, but also
on "gadgets" like PDA's, mobiles, a shipload of embedded applications and even on experimental
wristwatches. This makes Linux the only operating system in the world covering such a wide range of
hardware.
1.2. The user interface
1.2.1. Is Linux difficult?
Whether Linux is difficult to learn depends on the person you're asking. Experienced UNIX users will say no, because Linux is an ideal operating system for power-users and programmers, because it has been and is being developed by such people.
Everything a good programmer can wish for is available: compilers, libraries, development and debugging
tools. These packages come with every standard Linux distribution. The C-compiler is included for free - as
opposed to many UNIX distributions demanding licensing fees for this tool. All the documentation and
manuals are there, and examples are often included to help you get started in no time. It feels like UNIX and
switching between UNIX and Linux is a natural thing.
In the early days of Linux, being an expert was kind of required to start using the system. Those who mastered Linux felt better than the rest of the "lusers" who hadn't seen the light yet. It was common practice to tell a beginning user to "RTFM" (read the manuals). While the manuals were on every system, it was difficult to became easily discouraged from learning the system.
The Linux-using community started to realize that if Linux was ever to be an important player on the
operating system market, there had to be some serious changes in the accessibility of the system.
1.2.2. Linux for non-experienced users
Companies such as RedHat, SuSE and Mandriva have sprung up, providing packaged Linux distributions
suitable for mass consumption. They integrated a great deal of graphical user interfaces (GUIs), developed by the community, in order to ease management of programs and services. As a Linux user today you have all the means of getting to know your system inside out, but it is no longer necessary to have that knowledge in order to make the system comply to your requests.
Nowadays you can log in graphically and start all required applications without even having to type a single
character, while you still have the ability to access the core of the system if needed. Because of its structure,
Linux allows a user to grow into the system: it equally fits new and experienced users. New users are not
forced to do difficult things, while experienced users are not forced to work in the same way they did when
they first started learning Linux.
While development in the service area continues, great things are being done for desktop users, generally
considered as the group least likely to know how a system works. Developers of desktop applications are
making incredible efforts to make the most beautiful desktops you've ever seen, or to make your Linux
machine look just like your former MS Windows or an Apple workstation. The latest developments also
include 3D acceleration support and support for USB devices, single-click updates of system and packages,
and so on. Linux has these, and tries to present all available services in a logical form that ordinary people can understand. Below is a short list containing some great examples; these sites have a lot of screenshots that will give you a glimpse of what Linux on the desktop can be like:
• http://www.gnome.org
• http://kde.org/screenshots/
• http://www.openoffice.org
• http://www.mozilla.org
1.3. Does Linux have a future?
1.3.1. Open Source
The idea behind Open Source software is rather simple: when programmers can read, distribute and change
code, the code will mature. People can adapt it, fix it, debug it, and they can do it at a speed that dwarfs the
performance of software developers at conventional companies. This software will be more flexible and of a
better quality than software that has been developed using the conventional channels, because more people
have tested it in more different conditions than the closed software developer ever can.
The Open Source initiative started to make this clear to the commercial world, and very slowly, commercial
vendors are starting to see the point. While lots of academics and technical people have already been
convinced for 20 years now that this is the way to go, commercial vendors needed applications like the
Internet to make them realize they can profit from Open Source. Now Linux has grown past the stage where it was almost exclusively an academic system, useful only to a handful of people with a technical background.
                Now Linux provides more than the operating system: there is an entire infrastructure supporting the chain of effort of creating an operating system, of making and testing programs for it, of bringing everything to the users, of supplying maintenance, updates and support and customizations, etcetera. Today, Linux is ready to accept the challenge of a fast-changing world.
1.3.2. Ten years of experience at your service
While Linux is probably the most well-known Open Source initiative, there is another project that contributed enormously to the popularity of the Linux operating system. This project is called SAMBA, and its achievement is the reverse engineering of the Server Message Block (SMB)/Common Internet File System (CIFS) protocol used for file- and print-serving on PC-related machines, natively supported by MS Windows NT and OS/2, and Linux. Packages are now available for almost every system and provide interconnection solutions in mixed environments using MS Windows protocols: Windows-compatible (up to and includingWinXP) file- and print-servers.
Maybe even more successful than the SAMBA project is the Apache HTTP server project. The server runs on UNIX, Windows NT and many other operating systems. Originally known as "A PAtCHy server", based on existing code and a series of "patch files", the name for the matured code deserves to be connoted with the native American tribe of the Apache, well-known for their superior skills in warfare strategy and inexhaustible endurance. Apache has been shown to be substantially faster, more stable and more feature-full than many other web servers. Apache is run on sites that get millions of visitors per day, and while no official support is provided by the developers, the Apache user community provides answers to all your questions. Commercial support is now being provided by a number of third parties.
In the category of office applications, a choice of MS Office suite clones is available, ranging from partial to
full implementations of the applications available on MS Windows workstations. These initiatives helped a
great deal to make Linux acceptable for the desktop market, because the users don't need extra training to
learn how to work with new systems. With the desktop comes the praise of the common users, and not only
their praise, but also their specific requirements, which are growing more intricate and demanding by the day.
The Open Source community, consisting largely of people who have been contributing for over half a decade, assures Linux' position as an important player on the desktop market as well as in general IT application. Paid employees and volunteers alike are working diligently so that Linux can maintain a position in the market. The more users, the more questions. The Open Source community makes sure answers keep coming, and watches the quality of the answers with a suspicious eye, resulting in ever more stability and accessibility.