Red Hat Linux Operating System User Manual

Chapter 1
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Getting Acquainted with Linux
In This Chapter
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Describing Linux
Depending on GNU and the GPL
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Checking out popular Linux distributions
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Marveling at the Linux Company (or lack thereof)
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Telling Linux apart from the rest of the operating system pack
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Ford, you’re turning into a penguin. Stop it!
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— Arthur Dent
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elcome to the world of Linux, the operating system developed by over
a thousand people around the world! In this chapter, you find out
about Linux itself — what it is, where it comes from, and why it gets so much
attention in the news these days. Prepare to have your assumptions about
how software must be developed and sold challenged, and your mind opened
to new possibilities.
Is Free Really Free?
Understanding Linux requires a radical shift of thought regarding the way
that you acquire and use computer software. (Note: By radical, I mean getting
to the root of the matter rather than putting on beads and camping out in the
administration building.) Your first step toward shifting your mind-set is to
alter your general connotation of the word free to represent freedom, rather
than free lunch. That’s right; you can sell “free” software for a fee . . . and
you’re encouraged to do so, as long as you relay the same freedom to each
recipient of the software.
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Part I: Getting Your Feet Wet
Don’t scratch your head too hard; these concepts are tough to grasp initially,
especially when you consider the conditioning you’ve received from the marketing departments of the commercial software industry. Perhaps you don’t
know that when you purchase most proprietary, shrink-wrapped software,
you don’t actually own the software; rather, you’re granted permission to use
the software within the bounds dictated by the licensor.
Linux also has a license, but the motives and purpose of the license are much
different from those of most commercial software. Rather than use the license
to protect ownership of the software, the GNU General Public License (GPL)
that Linux is licensed under ensures that the software will always be open to
anyone. No company can ever own or dictate the way in which you use or
modify Linux — though they can have their own individual copyrights and
trademarks on their various brands of it, like Red Hat. In essence, you already
own Linux, and you can use it for anything you like, as long as you propagate
the GPL freedoms to any further recipients of the software.
Linux: Revolution or Just Another
Operating System?
Contrary to popular belief, penguins are not the salvation of modern
technology. Neither do they throw parties for the urban proletariat.
— Anonymous
Author note: Cute quote . . . obviously Anonymous has never been to a
Linux convention!
Before going any further into Linux, I need to get some terminology out of
the way.
Tux is the formal name of the mascot penguin that represents Linux. Rumor
has it that Linux’s creator, Linus Torvalds, is rather fond of these welldressed inhabitants of the Antarctic.
An operating system is the software that runs your computer, handling all of
the interactions between you and the hardware. Whether you’re writing a
letter, calculating a budget, or managing your recipes on your computer, the
operating system provides the essential air that your computer breathes.
Furthermore, an operating system isn’t just one program; it consists of hundreds of smaller programs and utilities that allow us humans to use a computer to do something useful. You then run other programs on top of the
operating system, like a word processor, to get everything done.
Chapter 1: Getting Acquainted with Linux
In recent technological history, Linux has evolved from water cooler techie
chatter to a rock-solid solution for the business enterprise. The same software that was once dismissed as rogue is now being adopted and promoted
by industry leaders such as IBM, Hewlett-Packard, Motorola, and Intel. Each
of these computer manufacturers has, in some way, determined that Linux
provides value for their customers (as well as for their own operations). Of
these companies, the only one that has publicly denounced Linux is Microsoft.
Note that one doesn’t have to look very far to conclude that Microsoft is
merely running scared from the threat that Linux poses to its personal computer operating system monopoly.
Linux has been accused of being “just another operating system.” On the surface, it may appear so, but if you look deeper, you can see that this isn’t so.
The Linux project is a flagship leading the current trend toward open source
and free (as in freedom, not free beer) software within the computing industry. A rock-solid operating system because of the model under which it was
(and continues to be) developed, Linux represents much that is good and
pure in software development.
Two fundamental distinctions separate Linux from the rest of the operating
system pack:
Linux is licensed under the unique and ingenuous GNU General Public
License, which you can read about in the next section.
Linux is developed and maintained by a worldwide team of volunteer
programmers, working together over the Internet.
Linux is great for many reasons, including the fact that the folks who built it
from the ground up wanted it to be:
Multiuser: More than one user can be logged in to a single computer at
one time.
Multiprocess: True pre-emptive multitasking enables the operating
system core to efficiently juggle several programs running at once.
This is important for providing multiple services on one computer.
Multiplatform: Linux currently runs on 24 platforms (hardware types),
including Intel-based PCs, Digital/Compaq Alpha, PowerPC-based Apple
Macintosh, Sun SPARC, Amiga, and StrongARM-based computers.
Interoperable: Linux plays nice with most network protocols (languages)
and operating systems, allowing you to interact with users and computers running Microsoft Windows, Unix, Novell, both Mac OS 9 and the
generation beginning with OS X, and other, more niche groups.
Scalable: As your computing needs grow, you can rely on Linux to grow
with you. The same Linux operating system can run on a desktop computer or a very large, industrial strength server system.
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Portable: Linux is mostly written in the C programming language. C is a
language created specifically for writing operating system-level software
and can be readily ported (translated) to run on new computer hardware.
Flexible: You can configure the Linux operating system as a network
host, router, graphical workstation, office productivity PC, home entertainment computer, file server, Web server, cluster, or just about any
other computing appliance that you can think of.
Stable: The Linux kernel (the operating system itself) has achieved a
level of maturity that makes most software developers envious. It’s not
uncommon to hear reports of Linux servers running for years without
crashing.
Efficient: The modular design of Linux enables you to include only those
components that you need to run your desired services. Even older
Pentium computers can utilize Linux and become useful again.
Free!: To most people, the most intriguing aspect of Linux is the fact
that it’s often free. How (the capitalists murmur) can anyone build a
better mousetrap with no incentive of direct monetary return?
So, where did Linux come from?
To understand Linux, you need to take a peek at
its rich heritage. Although programming of the
Linux core started in 1991, the design concepts
were based on the time-tested Unix operating
system.
Unix was developed at Bell Telephone
Laboratories in the late 1960s. The original
architects of Unix created it back when there
were few operating systems, with the desire to
have one that shared data, programs, and
resources both efficiently and securely —
something that wasn’t available at this time.
From there, Unix evolved into many different
versions, and its current family tree is so complicated it looks like a kudzu infestation!
In 1991, Linus Torvalds was a computer science
student at the University of Helsinki in Finland.
He wanted an operating system that was like
the Unix system that he’d grown fond of at the
university, but both Unix and the hardware it ran
on were prohibitively expensive. A Unix version
called Minix was available for free, but it didn’t
quite meet his needs. So, as a computer science student, Torvalds studied Minix and then
set out to write a new version himself. In his
own words (recorded for posterity on the
Internet since this was in an early version of an
online chat room), this was, “just a hobby, won’t
be big and professional like gnu.”
Writing an operating system is no small task.
Even after six months of hard work, Torvalds
had made very little progress toward the general utility of the system. He posted what he had
to the Internet and found that many people
shared his interest and curiosity. Before long,
some of the brightest minds around the world
were contributing to Linus’s project by adding
enhancements or fixing bugs (errors in the
code).
Chapter 1: Getting Acquainted with Linux
In this chapter, I intend to answer that last question for you. I also hope to
paint a picture of the open source software development model that created
Linux.
Anatomy of an Open Source
Software Project
Linux isn’t a product. Linux is an organic part of a software ecosystem.
— Michael Robinson, Netrinsics
To the casual observer (and some corporate IT decision-makers), Linux
appears to be a freak mutation — a rogue creature randomly generated by
anarchy. How, after all, can something so complex and discipline-dependent
as a computer operating system be developed by a loosely knit band of volunteer computer geeks from around the world?
Just as science is constantly attempting to classify and explain everything in
existence, technology commentators are still trying to understand how this
open source model can create superior software. Often, the reasons have much
to do with the usual human desire to fill a need with a solution. When a programmer in the Linux world wants a tool, the programmer simply writes one
or bands together with other people who want a similar package to write it
together.
GNU who?
Imagine — software created out of need rather than projected profit. Even
though Unix ultimately became expensive proprietary software, the ideas and
motives for its creation were originally based on need. What people usually
refer to in the singular as the Linux operating system is actually a collection of
software tools that were created with the express purpose of solving specific
computing problems.
Linux also wouldn’t be possible without the vision of a man whom Steven Levy
(author of the book Hackers) refers to as The Last of the Great MIT AI-LAB
Hackers — the original meaning of the word hacker, which meant someone
who plays with code, not the current meaning implying criminal intent. This
pioneer and advocate of freedom software is Richard Stallman.
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The Massachusetts Institute of Technology (MIT) has long held a reputation
for nurturing the greatest minds in the technological disciplines. In 1984,
Stallman, a gifted student and brilliant programmer at MIT, was faced with a
dilemma — sell his talent to a company for a tidy sum of money or donate
his gifts to the world. He did what we’d all do . . . right?
Stallman set out on a journey to create a completely free operating system
that he would donate to the world. He understands and continues to live the
original hacker ethic, which declares that “information wants to be free.” This
concept wasn’t new in his time. In the early days of the computing industry,
many advancements were made by freely sharing ideas and programming
code. Manufacturer-sponsored user groups brought the best minds together
to solve complicated problems. This ethic, Stallman felt, was lost when companies began to hoard software as their own intellectual property with the
single purpose of profit.
As you may or may not have gathered by this point, widespread and accessible
source code is paramount to successful software development. Source code is
the term for the human-readable text (as opposed to the unreadable ones
and zeros of binary code or an “executable”) that a programmer types to
communicate instructions to the computer.
Writing computer programs in binary is an extremely arduous task. Modern
computer software is usually written in a human-friendly language and then
compiled, or translated, into the computer’s native instruction set. To make
changes to this software, a programmer needs access to a program’s source
code. Most proprietary software comes only as precompiled, and the software
developer keeps the source code for those programs under lock and key.
After determining that his operating system would be built around the conceptual framework of Unix, Stallman wanted the project name to distinguish
his system from Unix. So, he chose the recursive acronym GNU (pronounced
ga-new), which means GNU’s Not Unix.
To finance the GNU project, Stallman organized the Free Software Foundation
(FSF), which sold free software to help feed the programmers who worked on
its continuing development. (Remember, we’re talking free as in free speech,
not free beer.) Although this organization and goal of creating a complete operating system was necessary and important, a much more important piece of
the puzzle had to be put into place to protect this new software from big
business pirates — a concern still all too relevant today as a former Linux
company tries to hijack ownership of decades of volunteer work from thousands of people around the world.
The GNU General Public License (GPL) is a unique and creative software license
that uses copyright law to protect the freedom of the software user, which is
usually the opposite of how a copyright works. Generally, a copyright is an
enforceable designation of ownership and restriction from duplication by
Chapter 1: Getting Acquainted with Linux
anyone but the copyright holder. When software is licensed under the GPL,
recipients are bound by copyright law to respect the freedom of anyone else
to use the software in any way they choose. Software licensed with the GPL is
also known as copyleft software. Another way to remember the GPL is through
its ultimate result: Guaranteed Public for Life.
Who’s in charge of Linux anyway?
As an open source project evolves, various people emerge as leaders. This
leader is often known as the project’s benevolent dictator. A person who
becomes benevolent dictator has probably spent more time than anyone
else on a particular problem and often has some unique insight. Normally,
the words democratic and dictator are never paired in the same sentence,
but the open source model is a very democratic process that endorses the
reign of a benevolent dictator.
Linus Torvalds is still considered the benevolent dictator of the Linux kernel
(the operating system’s core). He ultimately determines what features are
added to the kernel and what features aren’t. The community trusts his vision
and discretion. In the event that he loses interest in the project, or the community decides that he has gone senile, a new leader will emerge from amongst
the very competent people working with him.
Einstein was a volunteer
Someone who is a volunteer or donates their time to a project isn’t necessarily providing a second-rate effort or only working on weekends and holidays.
In fact, any human resource expert will tell you that people who choose to do
a job of their own free will produce the highest quality products.
The volunteers who contribute to open source projects are often leaders in
their field who depend on community collaboration to get useful work done.
The open source concept is no stranger to the scientific community. The
impartial peer-review process that open source projects foster is critical in
validating something as being technically correct.
Those who paint the open source community as copyright violators and
thieves often misunderstand or outright ignore these vital issues. Open
source programmers are very proud of their work and are also very concerned about their own copyrights, not wanting their work to be stolen by
others — hence licenses such as the GPL. This concern creates an atmosphere with the greatest respect for copyright. Those who claim that they are
just being “open source” when they steal other people’s hard work are
grossly misusing the term to soothe their own consciences.
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Many have also pointed out that if copyright is violated in open source, it is
easy to tell. Watch the news and notice how often large software corporations
are convicted of stealing other people’s code and incorporating it into their
own work. Tracking down such copyright violations is incredibly difficult in a
closed source scheme.
Packaging Linux: The Distribution
What people call a Linux distribution is actually the culmination of the GNU
project’s tools, the Linux kernel, and any number of other open source
(and closed source) software projects that sprang up along the way.
Robert Young, cofounder and current chairman of Red Hat, has coined an
analogy comparing Linux to ketchup. Essentially, the operating system called
Linux, with the GNU tools, Linux kernel, and other software, is a freely available commodity that, like ketchup, different distributors can package and
label in different containers. Anyone is encouraged to package and market
the stuff, even though the ingredients are fundamentally the same.
Linux is a complex, malleable operating system, and thus it can take on many
appearances. The greatest Linux advancement in recent years has been making
it easier to install. After all, the tools that today enable the casual PC user to
install Linux originally weren’t available. Companies such as Red Hat saw this
as an opportunity to add value to an existing product, and the concept took
off like gangbusters.
To draw again on the ketchup analogy, various distributions of Linux have a
slightly different flavor or texture; your distribution preference may be spicy,
mild, thick and gooey, or runny. However, you can rest assured that any of
the following distributions have the same Linux and GNU heart and soul.
Each short description includes a Web address where you can find more
information about each project:
Debian GNU/Linux: This distribution is one of the oldest and is a recognized favorite among advanced technical circles. Historically, it’s relatively difficult to install. The Debian team works closely with the GNU
project and is considered the most “open” of the Linux distributions.
Easier to install (and use) distributions with Debian underneath are
Xandros and Linspire (formerly known as Lindows).
www.debian.org
www.xandros.com
www.linspire.com
Mandrake: This distribution demonstrates the power of the GPL by
allowing this competing company to stand on the shoulders of giants.
Chapter 1: Getting Acquainted with Linux
Mandrake was originally based on Red Hat Linux, something that simply
could not happen in a closed source environment, but has since become
an excellent solution in its own right.
www.mandrakelinux.com
Red Hat and Fedora: Red Hat claims the prize for successfully mass
marketing the Linux operating system. Red Hat has validated Linux by
packaging the GNU and Linux tools in a familiar method of distribution
(shrink-wrapped) and has included value-added features to its product,
such as telephone support, training, and consulting services.
www.redhat.com
http://fedora.redhat.com/
Slackware: Of all the more recognized surviving Linux distributions,
Slackware has been around the longest. In fact, until about a year ago,
the installation interface remained unchanged. Slackware has a very
loyal following, but isn’t well known. Like Debian in terms of spirit, the
Slackware crowd is respected in Linux circles as the weathered old-timers
who share stories of carrying around a shoebox full of diskettes.
www.slackware.com
SuSE: (Pronounced soo-za) This distribution hails from Germany, where
it has a very loyal following. SuSE works closely with the XFree86 project
(the free X graphical server component of all Linux distributions). Consequently, SuSE has a terrific graphical configuration tool called SaX.
www.suse.com
As you can see, many paths (in the form of distributions) lead to Linux. It’s
important to note that, regardless of which distribution you choose, you’re
using the same basic ingredients: the GNU tools and the Linux kernel. The
major differences that you’ll encounter among distributions are
Installation programs: Each distribution has developed its own installation program to help you achieve a running system. Some installation programs are designed for the casual computer user (hiding the technical
details), whereas others are designed with the seasoned system administrator in mind. Some of the simpler ones offer an “expert mode” for
those who want to have more control right from the beginning.
Software versions: Different distributions may use different versions of
the kernel (the core of the operating system) and other supporting software packages. Open source projects are dynamic and release new versions regularly, as opposed to the often sluggish development cycle of
traditional commercial software.
Package managers: Even though one Linux program should be able to
run on any distribution, tools called package managers keep track of the
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software on your system and ensure that you have all the required supporting software as well. Distributions are usually dependent on one
particular package manager. More recent in the grand scheme of things,
package management has also come to involve adding easy-to-use update
routines as well as the ability to add software without needing a computer
science degree.
It would be impossible to account for every possible installation of every
Linux distribution. Okay, maybe not impossible, but you would need a forklift
to bring your Linux For Dummies book home from the bookstore if I did.
Consequently, I try to summarize the concepts needed to install any Linux
distribution into this one book with enough detail to get you through the
process. As you can imagine, this is a bit of a challenge!
I chose Fedora Core as the sample distribution because Red Hat has become
a recognized Linux standard, and its Fedora Core project is specifically aimed
at home and small business users who cannot afford or have no need to purchase higher-level products. Even better, if you do use Red Hat Enterprise
Linux (RHEL) in your office or organization, Fedora Core is a proving ground
for the technologies that will make their way into RHEL.
In addition to Red Hat coverage, I also include information about other popular distributions with beginners: Linspire, Mandrake, SuSE, and Xandros. I
certainly don’t wish to discount Slackware and Debian because these are
very powerful distributions. I just feel that they are more advanced than the
others and best left for your post-Linux For Dummies endeavors. Included
also is Knoppix, a Live CD that you can use to boot your computer into a full
desktop without having to install a thing!
In fact, the DVD that comes with this book contains more than just Fedora.
Check out Appendix B for a list of what you can find on the DVD.
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