Understanding Unix and Linux

Unix is another popular operating system. It is a 32-bit, multiuser, multitasking operating system. Linux is a derivative of the Unix operating system.

Unix

shareware

Software that is generally available for trial use. If you like the software, you should pay a small licensing fee.

freeware

Software that you can use without payment.

Unix was first developed in the late 1960s as an operating system for mainframe computers. The original development team consisted of Bell Telephone Laboratories, General Electric, and Massachusetts Institute of Technology (MIT). During the early development of Unix, many universities were able to obtain the Unix operating system by signing nondisclosure agreements that allowed them to use the software for educational purposes. Computer science students gained experience with Unix and contributed to its development.

Today two major versions of Unix exist:

• Unix System Laboratories (USL) System V UNIX

• Berkeley Software Distribution (BSD) Unix

There also are many other flavors of Unix, but most are derivatives of the versions listed above.

Different versions of Unix have been produced as commercial software, shareware, and freeware. Each variation has its own features and offers different levels of hardware and software support. Different versions of Unix are also designed to support specific hardware platforms-for example, Intel, RISC, Alpha, and PowerPC.

Because the Unix operating system was designed for engineers by engineers, it has a stigma of being difficult to use and is not as user-friendly as other operating systems. A standard for Unix called X Windows provides a graphical interface for Unix, making it easier to use.

Note 

You may notice that Unix is referred to as both Unix and UNIX. When Unix is used, it specifies Unix in general. When UNIX is used, it specifies the Unix used by USL and is a trademark name.

Linux

Linux is an independent operating system that is similar in nature to Unix. The beauty of Linux is that it uses no proprietary code and is freely distributed. The code for Linux is developed and produced by the Free Software Foundation's Gnu's Not Unix (GNU) project. Linux is offered as freeware through the Web, and many applications have been written for Linux as shareware.

open source

Providing the source code for software free for anyone to develop to improve the application, with some licensing, authoring, and other restrictions.

College student Linus Torvalds first introduced Linux to the world in 1991 as a hack operating system. By the end of the year, 100 people were using the operating system, sending feedback, and adding contributions to the code. In 1999, it was estimated that there were more than 20 million Linux users worldwide.

Linux is a popular version of Unix because it is open source software and can be distributed only for free or for a minimal cost. Many of the utilities included with the distribution of Linux are also freeware or shareware. This makes Linux an attractive offer for people who want a powerful desktop operating system at little or no cost.

Linux supports all the major software that is produced for the Unix operating system. It is mostly compatible with System V, BSD, and POSIX. It is primarily designed to run on an Intel platform but has been ported to other platforms.

The advantages of Linux include the following:

• It is a true 32-bit operating system.

• It supports preemptive multitasking.

• It offers the capability to support multiple users and includes networking capabilities.

• Security features are included, such as login/password, and directory and file permissions.

• The distribution software includes development software.

The disadvantages of Linux include the following:

• The software that ships with Linux tends to be very basic.

• Text-based versions of Linux are difficult to learn. X Windows Linux is easier to use.

• Linux accesses hardware directly, as opposed to going through a software interface, so hardware problems are more common under Linux than with Windows 2000/XP or other Unix operating systems.