Introduction

What is Linux? Linux is a multiuser, multiprocessor, multiplatform operating system, which runs on different platforms, such as Intel, PowerPC, and more.

Linux was born from an idea by Linus Torvalds, a student at the University of Helsinki in Finland.

Public domain software has been popular for many years and was forged from programs like TeX, written by Dr. Donald Knuth, from the X-Window System created at MIT, from utilities, and from serious compilers originating from the Free Software Foundation (GNU project). All these tools found the missing link in Mr. Torvalds' Kernel for creating one operating system (OS) available for everyone as public property.

Therefore, the complete operating system is best known as GNU/Linux, Linux being only part of its name. What we call "Linux" actually consists of:

• A UNIX File System hierarchy: "/", "/etc/", "/usr/bin", and so on.
• The Shell, the program that allows you to send commands to the system.
• The Kernel, a set of objects which supports the hardware.
• The X-Window system, a graphical interface created at MIT and supported by the XFree86 organization.
• The utilities, programs, compilers, and editors developed by GNU.
• The connectivity files: TCP/IP, NFS, PPP, HTTP, and others.
• And thousands of programs that vary according to distribution.

UNIX® was born in the '60s in the Bell laboratories by Kerningham and Ritchie; Linux is in effect a copy of UNIX®. Linux makes use of a new philosophy developed at the University of California at Berkeley and legally ratified in the GPL (General Public License) by the Free Software Foundation. This philosophy allows a person to write a program that performs a certain task, even with the same interface as an existing program, but it must be written from scratch. That's how GNU has created development systems software such as gcc, instead of cc, and gawk, instead of awk, and others.

There are thousands of companies in the world that work on Linux. Then there are other companies like RedHat, Caldera, MandrakeSoft, and SuSE, who, starting from a freely downloadable version of Linux, have successfully created a commercial distribution. Why commercial? Can they? Yes, undoubtedly: GPL allows anyone to create their own Linux distribution. It has become commercial for obvious reasons: A company can't 'risk' using an operating system without a guarantee of product support.

The aim of Linux companies today is to give product assistance service, so that all the firms that use Linux feel safe. Caldera, RedHat, SUSE, and their distributors offer assistance to the client or company that utilizes a particular type of Linux distribution.

Why Linux? Linux, like UNIX®, is a complete operating system. Generally, a person who buys a PC with MSWindows 95 must buy tens or hundreds of other products, such as: Norton Utilities (to use the computer better), anti-virus programs, programs like WinZip for compressing files and directories, and office packages like MSOffice or Lotus SmartSuite. A few years ago, a program for navigating the Internet had to be bought; today, the program for browsing or reading e-mail or for conducting discussions, news groups, and others is free.

In Linux (and UNIX variants) commands are case-sensitive. For example, FTLinuxCourse in Linux and UNIX based systems is just how we wrote it, but on DOS it would be FTLINUXCOURSE. Linux commands generally run in lowercase.
For example, you may have two users, george and George, who have completely different enviroments and passwords.
 

Yes, Linux is multiuser. This means that the same machine may work with any number of users. Some years ago Unix versions like SCO (today it is a part of Caldera Systems), Interactive (today it is a part of SunSoft), and other multiuser features were available for an additional US $500 or more per user. Linux offers all its utilities, compilers, and graphical interface at no additional cost.

With Linux, a large number of these programs are included. For example, in choosing to use the ext2 File System, Linux doesn't have to perform the usual defrag for compressing space, because every new file is lined up at the end of the disk. Every distribution includes the gzip program, which is much more efficient than commercial ones, currently updated to bzip2. Every distribution also includes TCP/IP, PPP, and other programs for connecting to the Internet, and some also include Netscape Navigator for sending e-mail and consulting newsgroups. Every distribution includes a gcc, Tcl/Tk, or perl compiler. These tools allow you to develop multiplatform graphic or character applications. This capability can save a developer several millions of dollars. Every distribution includes the httpd Apache demon, the most used product for implementing Internet web servers in the world. Today, all distributions offer a complete suite of office programs, such as StarOffice, which includes: a word processor, an electronic worksheet, a program for sending e-mail, a program for making drawings and presentations, and it's completely compatible with the most well-known Office suites.

Additionally, Linux isn't damaged by the usual viruses. It would be contradictory to write virus programs for an open system like Linux; viruses have never been heard of even on UNIX.

In summary, we can say that among the reasons that make us decide to choose Linux are its low cost and the pleasure of having everything necessary to do a day's work.

Are there any other reasons? Certainly. The most important one is performance together combined with great reliability. Linux is much more reliable than any other operating system in use today. In comparison to MSWindows 95/98/NT or 2000, there's absolutely no comparison. Linux's performance is undoubtedly the best. A Linux system may run for years without any administration.

At this point we ask ourselves: Why would people who work with UNIX, Workstation UNIX: HP, IBM, DIGITAL, SUN, or MAC, MSWindows, or OS/2 change to Linux?

The answer is simple: Linux offers the same product with better performance, better reliability, and the same graphic interface, at a far lower price.

In fact the advantages that Linux offers are evident when compared with other UNIX versions. With respect to other interfaces, such as Windows or MAC, we should add that Linux offers the X-Window system, developed many years before the popular MSWindows. Thanks to its structure, the X-Window system can change its graphic interface and transform from a Windows95-like system to a MAC-like, Amiga-like, or any other type of system.

However, many companies have dedicated several years to developing their programs on SCO/UNIX, Macintosh, Windows, DOS, and other systems. How can they change to Linux without losing all those invested years?

Linux includes several emulators: some commercial, some free. Nearly all distributions include the iBCS emulator, which allows you to make use of binaries without any change. For example, the programs developed for SCO UNIX run exactly the same under Linux. Under DOS there's dosemu, included in Linux, while for Windows there's WABI, which supports MSWindows 3.1 applications, and Wine, which supports MSWindows 95 and 97 applications. There's also Executor for Macintosh. If you want to study these in more detail, you can consult Appendix E: The Linux Emulators. WMWare is the latest choice, which creates virtual machines on which it is possible to install any operating system.

In the end, Linux offers everything. No company can compete with excellent products at prices as cheap as those of Linux's commercial distributions.

All the major companies will port their product to Linux, including Adobe (Acrobat reader and FrameMaker) and Macromedia (Generator for RedHat Linux).

Corel already has its Linux Office suite, including Corel WordPerfect, PhotoPaint in its distribution.

Is it true that the latest market hardware drivers can't be found on Linux? As with other operating systems, Linux supports all hardware. However, there are some slight gaps for some parallel scanners or for viewing DVD films, but both are being resolved. You can consult Appendix H: Hardware Compatibility List.

What is the secret of Linux's success?

Linux's success is fundamentally due to its users. Linux was created by people who have worked, and continue to work, free of charge. In any case, it's very important to clarify that while Linux is free, its products or commercial distributions are not; however, serious companies likes RedHat, Mandrake, Caldera, and Corel offer their distributions of ISO images, 650 MB, for download the same day they release it.

StarOffice, better than MSOffice, is also available for free. Can you believe it? A complete Operating System and a complete Office suite-all at no cost. It's a new millenium-without bugs!