Unix Overview

Because of growing market share from companies such as Red Hat, Sun, IBM, and Novell, it's no wonder that Unix is becoming more and more of a household name. Unix (and Linux, which is Linus Torvald's version of Unix) is now found in most firewall and Web-server-based systems as well as all the way to the desktop for end user productivity and development. Unix has deep roots in the computer industry. First surfacing in universities and the military, it began to grow more and more in use with the massive development and expansion of the Internet. Once Linux was released, the landscape of Unix changed forever. Now, Linux (an easier to use version of the Unix operating system) and Unix are both found almost everywhere you look, and to ignore them is simply impossible.

Some common versions of Unix (called distributions, or distros for short) you may have heard of are Sun Solaris, IBM AIX, FreeBSD, Red Hat Linux, SuSE Linux (also known as Novell SUSE), and SCO ACE. Although these versions of the Unix operating system have differences, they all share the same thing: a basic Unix kernel that can be openly worked on and developed by anyone with the knowledge to do so. In this book, we will focus on the similarities between all versions of Unix so that you can use any one of them and still be productive.

Unix is a very powerful multitasking operating system. Multitasking refers to performing multiple tasks at once; in this context, it more specifically means that a user can run multiple programs simultaneously within one single logon of the system. Unix is also a multiuser operating system. What this means is that many users can simultaneously (and securely) use the same machine. In addition, Unix is open source software, which means that users are free to look at and modify its code. This is not the case with proprietary versions of Unix, but most versions are open source, so unless you are working with a specific vendor that does not allow its version of Unix to be altered, it's safe to assume that most versions (especially Linux versions) can be modified. Another powerful tool to unleash with Unix is the power of coding and scripting. Entire user communities work with and help develop Unix programs, and this is what keeps the system growing, developing, and getting better each and every year. This is not commonly seen with other proprietary operating system platform vendors such as Microsoft. Most of these vendors release closed source systems, which means you cannot freely write code that works blindly with these systems.

There is much more to learn about Unix. You are encouraged to find out more about its history and origins on the Web; this way, we can focus more written pages on teaching you how to use Unix. (At the end of this book, however, there is a reference section that will help you locate additional information on Unix, its history, and where it is going in the future.) So, now that you know that Unix is rapidly growing in use, let's take a second to understand why this book is so important, how this book should be used, how this book is organized, and how you will learn Unix productively.