GNU and Linux

In 1984 Richard Stallman began work on a free operating system called GNU (a reverse acronym, that is, an acronym that refers to itself, for GNU is Not UNIX). Stallman founded the Free Software Foundation, a nonprofit organization supporting the creation and sharing of free software, and in particular, the GNU project. The goal of the GNU project was to make GNU like UNIX, without using any UNIX source code. Stallman wanted to develop an operating system that could evolve through the work of a community, with users free to study the source code and to modify and publish enhancements to it. Because constructing an entire operating system, including the kernel and user utilities, is a daunting task, GNU was designed to be modular so that different people could develop different parts of the operating system and so that it could easily incorporate already existing free software. By 1990 GNU had its own versions of the almost all the utilities, tools, and core libraries of UNIX, as well as the emacs text editor and a C compiler, GCC. However, it lacked a kernel, and initial efforts to develop one were not entirely successful.

Meanwhile, in 1991 Linus Torvalds, then a student at the University of Helsinki, Finland, decided to build a kernel for a new UNIX-like operating system for PCs. Torvalds had been working with the Minix operating system built by Andrew Tannenbaum to illustrate features of UNIX. Torvalds wanted a UNIX version for PCs that captured the features of Minix. He considered his work on this new kernel, which was eventually named Linux, to be a hobby and thought his new operating system would never become anything remotely like a professional-quality operating system. Torvalds invited other people to download a copy of his new kernel over the Internet and to improve and add to it. Many people decided to take up Torvalds’s offer, relating to his goals and the inherent technical challenges. They worked alone, and in teams, to improve Linux. All this work was, and continues to be, done under the direction of Linus Torvalds, with communication and collaboration done over the Internet.

A key goal of the developers of Linux kernel is not to use any proprietary code. The kernel is legally protected by the GNU Public License; it is packaged with many executables making up a fully functional version of UNIX. Combined with GNU software, containing UNIX-like utilities, tools, core libraries, compilers, text editors, desktop environments, and other components, Linux (sometimes called GNU/Linux) provides a complete UNIX environment.

The latest major release of the Linux kernel is Linux 2.6, which was introduced in 2003; minor releases are frequently made. The Linux 2.6 kernel supports 64-bit computing (that is, computing that supports addressing up to 2⁶⁴ bytes of virtual memory, which far exceeds the amount needed to support even 4 GB of RAM) and hyperthreading (which allows multiple threads of computer code to run at the same time on Intel Pentium IV processors, providing improved performance and allowing more users to be supported on a server). It provides performance improvements for database applications and for networking and offers increased levels of security.

Linux has become increasingly popular and receives wide attention in the computer industry Linux has become popular because, among other reasons, it is free, a large community of developers is constantly adding new features and capabilities to Linux, and many people relate to the philosophy behind Linux. This philosophy, which endorses the notion that software should be open and free, runs counter to the way Microsoft has done most of its business. (For example, Microsoft has long kept the code for its Windows operating system closed.) To use Linux, you need to obtain a Linux distribution. We will discuss Linux distributions later in this chapter when we discuss widely used UNIX variants.

The SCO Lawsuit

Although Linux has been designed to be free of commercial code, in 2003 the SCO Group filed a lawsuit against IBM. The SCO Group claimed that IBM had contributed some code that was protected by an SCO Group copyright to Linux, violating the license IBM holds to use UNIX. Also, the SCO Group filed suits against other companies. This controversy has not yet been settled, although most experts feel that the SCO Group is incorrect in their assertions of copyright infringement. These experts feel that these SCO Group lawsuits will ultimately be dismissed.