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Linux is one of the hottest buzzwords in the world of computers, but beyond that, what is it? Simply put, Linux is an operating system. Which of course begs the question, “what is an operating system?” In simple terms, an operating system is software that runs your PC. Microsoft Windows is another operating system, as is the Apple OS X®. Of course, you are familiar with the various applications you run on your PC, such as word processors, graphics utilities, spreadsheets, and even games. An operating system is like these other applications, except that rather than create a document or play a game, it actually runs your PC. When you move a file, delete a file, create a directory, load software, etc., it is your operating system that performs all of these tasks. Without an operating system, your PC is really just a pile of useless circuits, worth less to you than a toaster. The operating system is what is running your machine. In addition to communicating with your printer, displaying output to your monitor, and running your CD-ROM, it has other functions. Your operating system provides a context within which your applications run. For example, your favorite word processor must run within the context of your computer’s operating system. When you print, your word processor talks to the operating system, which in turn handles the printing. The operating system is, essentially, the soul of your computer.
There are other operating systems available for you to use. You are probably familiar with Microsoft Windows (Windows 98, 2000, or XP). Windows is a very popular operating system for home users and small businesses. In fact, in its various versions, Windows is the predominant desktop operating system. It is hard to find a modern office without computers running Windows. Most home users have a Windows PC. This is obvious when you go to any store that sells computer software. Most commercial software stores carry predominantly Windows software, with only a small selection of titles for other operating systems. Another popular operating system is Apple Macintosh OS (short for operating system). As of this writing, the Macintosh OS is up to version 10, popularly referred to as OS X. Macintosh is easy to use and has been particularly popular with the graphics and computer animation industries. Many very high-end computer graphics companies use Apple computers. Many of the special effects you see in movies were probably created, or at least augmented, with Apple computers. Another operating system that generally is used for high-end servers, not for desktops, is Unix, which is known for its stability and security, but also for its expense.
This brings us to Linux. Linux is a variant of Unix. In fact, many people now use the term nix to refer to Unix and its variants. Linux is an operating system that has some rather unique features. First, it is very stable and robust, being based on the time-honored Unix operating system (more on that in the next part of this chapter). Second, it is distributed under an open source license. Open source licensing is rather simple, yet elegant. Open source means that once you obtain a piece of software, it is yours to do with as you please. Would you like to make a copy or change the source code? Under open source, the source code of the software is open to the public, and when you purchase a product, it is yours to do with as you will. In case you did not realize it, this is radically different from Microsoft, Oracle®, Sun®, and most commercial software. For example, when you buy Microsoft Windows, the manufacturer’s licensing agreement that comes with the product places rather significant restrictions on what you can do with that product. Violating that license agreement can result in losing the license to that software and, in some extreme cases, in lawsuits. Each vendor’s licensing agreement stipulates what is acceptable use of its software and what is not. Most commercial vendors do not allow you to alter their software, nor do they allow you to have access to the source code for the software. Most vendors also do not allow you to make or distribute copies of their software after you purchase it. One example of software licensing restrictions is that if you purchase a computer that comes with Windows, you cannot later sell that copy of Windows, even if you have disposed of the machine. Several eBay® sellers have been shut down by Microsoft for just that sort of activity. Also, you most certainly do not have access to its source code. With open source software, you can do anything you want with the software once you get it, and you have complete access to the source code.
For those readers who may not know what source code is, it is the programming commands that were written to create a piece of software. With commercial software, source code is usually carefully guarded. With open source software, it is freely distributed.
Access to source code may not be particularly intriguing to many readers. You have to be a rather highly skilled programmer to make much use of it. However, if you have skilled programmers on staff, they can take the Linux source code and make modifications to customize the operating system for your particular needs.
One note of caution is in order. What you can do with open source software is not completely unlimited. For example, you cannot put your own label on open source software and resell it. The open source license does not give you this right. If you put Red Hat® Linux and your name on a CD-ROM and then started selling copies, you might find yourself the target of litigation and possible criminal charges. The author does not claim to be an attorney and recommends that with any software, you read the licensing agreement carefully. Open source software has the least restrictive licensing of any software you can find, far less restrictive than commercial software. However, there are still some limitations. It is recommended that you look at www.opensource.org/ to see a wealth of information and links on open source software.
One advantage of an open source operating system is that a lot of the software written for the operating system also is open source. This means that, although the software selection for Linux in an average retail store might be slim, the selection of freely downloadable software on the Internet is vast.
You will also find that the Linux community is rather supportive of itself. You will find several links in the appendices of this book, and it is even possible that you might find a Linux users group in your area, especially if you live in a major metropolitan area. These people can be quite helpful to the Linux novice.
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