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Debian Tutorial (Obsolete Documentation)
Chapter 2 - Introduction

2.1 What is Debian?

Debian is a free operating system (OS) for your computer. An operating system is the set of basic programs and utilities that make your computer run. At the core of an operating system is the kernel. The kernel is the most fundamental program on the computer: it does all the basic housekeeping and lets you start other programs. Debian uses the Linux kernel, a completely free piece of software started by Linus Torvalds and supported by (probably over 1000) programmers worldwide. A large part of the basic tools that fill out the operating system come from the (GNU project), and these tools are also free. Of course, what people want is application software: programs to help them get what they want to do done, from editing documents to running a business to playing games to writing more software. Debian comes with over 1000 packages (precompiled software bundled up in a nice format for easy installation on your machine) --- all of it free.

It's a bit like a tower. At the base is Linux. On top of that are all the basic tools, mostly from GNU. Next is all the application software that you run on the computer: much of this is also from GNU. The Debian developers act as architects and coordinators --- carefully organizing the system and fitting everything together into an integrated, stable operating system: Debian GNU/Linux.

2.1.1 What's an operating system, and what sort of operating system is Debian?

An operating system is the collection of software that makes a computer usable. It manages hardware devices and provides utilities and applications.

Debian GNU/Linux is based on the Unix operating system, which has a long history (see Unix History, Section D.1). Debian is basically compatible with Unix, but adds a significant number of additional features.

The design philosophy of GNU/Linux (and Unix) is to distribute its functionality into small, multipurpose parts. That way, you can easily achieve new functionality and new features by combining the small parts (programs) in new ways. Debian is like an erector set; you can build all sorts of things with it.

When you're using an operating system, you want to minimize the amount of work you put into getting your job done. Debian supplies many tools that can help you, but only if you know what these tools do. Spending an hour trying to get something to work and then finally giving up isn't very productive. This manual will teach you about the core tools that make up Debian: what tools to use in what situations, and how to tie these various tools together.

2.1.2 Who creates Debian?

Debian is an all-volunteer internet development project. There are hundreds of volunteers working on it. Most are in charge of a small number of software packages and are intimately familiar with the software they package.

These volunteers work together by following a strict set of guidelines governing how packages are assembled. These guidelines are developed cooperatively in discussions on internet mailing lists and internet relay chat (IRC) forums.

2.2 What's free software?

When Debian developers and users speak of "free software", they refer to freedom rather than price. Debian is free in this sense: you are free to modify and redistribute it, and will always have access to the source code for this purpose. The Debian Free Software Guidelines describe in more details exactly what is meant by "free". The Free Software Foundation, originator of the GNU project, is another source of information. You can find a more detailed discussion of free software on the Debian web site.

Free software is sometimes called Open Source (R) software --- Open Source is a certification mark. Since Open Source (R) is trademarked, only truly free software can call itself Open Source (R). You may encounter vendors who try to mislead you by claiming their software is "free", while in reality it has significant strings attached. The Open Source (R) trademark gives you some assurance that the software really is free software. 'Open Source software' is occasionally abbreviated 'OSS'.

You may be wondering: why would people spend hours of their own time to write software, carefully package it, and then give it all away? The answers are as varied as the people who contribute.

Many believe in sharing information and having the freedom to cooperate with one another, and feel that free software encourages this. There's a long tradition starting in the 1950s upholding these values, sometimes called the Hacker Ethic. (You can read more about it in Steven Levy's enjoyable book, Hackers: Heroes of the Computer Revolution.)

Others want to learn more about computers. More and more people are looking for ways to avoid the inflated price of commercial software. A growing crowd contribute as a thank you for all the great free software they've received from others.

Many in academia create free software to help get the results of their research into wider use. Businesses help maintain free software so they can have a say in how it develops --- there's no quicker way to get a new feature than to implement it yourself or hire a consultant to do so! Business is also interested in greater reliability and the ability to choose between support vendors.

Still others see free software as a social good, democratizing access to information and preventing excessive centralization of the world's information infrastructure. Of course, a lot of us just find it great fun.

Debian is so committed to free software that we thought it would be useful if it was formalized in a document of some sort. Our Social Contract promises that Debian will always be 100% free software. When you download a package from the Debian main distribution, you can be sure it meets our Free Software Guidelines.

Although Debian believes in free software, there are cases where people want or need to put proprietary software on their machine. Whenever possible Debian will support this; though proprietary software is not included in the main distribution, it is sometimes available on the ftp site in the non-free directory, and there are a growing number of packages whose sole job is to install proprietary software we are not allowed to distribute ourselves.

It is important to distinguish commercial software from proprietary software. Proprietary software is non-free software, while commercial software is software sold for money. Debian permits commercial software to be a part of the main distribution, but not proprietary software. Remember that the phrase "free software" does not refer to price; it is quite possible to sell free software. For more clarification of the terminology, see http://www.opensource.org or http://www.fsf.org/philosophy/categories.html.

2.3 How to Read This Book

The best way to learn about almost any computer program is at your computer. Most people find that reading a book without using the program isn't beneficial. The best way to learn Unix and GNU/Linux is by using them. Use GNU/Linux for everything you can. Experiment. Don't be afraid --- it's possible to mess things up, but you can always reinstall. Keep backups and have fun!

Debian isn't as intuitively obvious as some other operating systems. Thus, you will probably end up reading at least the first few chapters. GNU/Linux is like a race car, a master chef's kitchen, or a classic novel; its power and complexity make it difficult to approach at first, but far more rewarding in the long run.

The suggested way to learn is to read a little, then play a little. Keep playing until you're comfortable with the concepts, and then start skipping around in the book. You'll find a variety of topics are covered, some of which you might find interesting and some of which you'll find boring. After a while, you should feel confident enough to start using commands without knowing exactly what they do. This is a good thing.

A helpful thing to know: if you ever mistakenly type a command, or don't know how to exit a program, C-c (the Ctrl key and the lowercase letter c held simultaneously) will often stop the program.

2.4 The Linux Documentation Project

This manual borrows heavily from the Linux Documentation Project's Linux User's Guide, by Larry Greenfield. Thanks Larry! That project has a number of other excellent manuals, many of them targetted at more experienced users and system administrators. The LDP also maintains the Linux HOWTOs, an invaluable resource you should become familiar with. You can find the LDP at their homepage.

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Debian Tutorial (Obsolete Documentation)

29 Dezember 2009

Havoc Pennington hp@debian.org