Successful marketing of UNIX systems at the time, however, was happening with other computer companies. SCO had found a niche market, primarily selling PC versions of UNIX running dumb terminals in small offices. Sun Microsystems was selling lots of UNIX workstations (originally based on BSD but merged with UNIX in SVR4) for programmers and high-end technology applications (such as stock trading).
Other commercial UNIX systems were also emerging by the 1980s. This new ownership assertion of UNIX was beginning to take its toll on the spirit of open contributions. Lawsuits were being initiated to protect UNIX source code and trademarks. In 1984, this new, restrictive UNIX gave rise to an organization that eventually led the path to Linux: the Free Software Foundation.
GNU transitions UNIX to freedom
In 1984, Richard M. Stallman started the GNU project (https://gnu.org), recursively named by the phrase GNU is Not UNIX. As a project of the Free Software Foundation (FSF), GNU was intended to become a recoding of the entire UNIX operating system that could be freely distributed.
The GNU Project page (https://gnu.org/gnu/thegnuproject.html) tells the story of how the project came about in Stallman's own words. It also lays out the problems that proprietary software companies were imposing on those software developers who wanted to share, create, and innovate.
Although rewriting millions of lines of code might seem daunting for one or two people, spreading the effort across dozens or even hundreds of programmers made the project possible. Remember that UNIX was designed to be built in separate pieces that could be piped together. Because they were reproducing commands and utilities with well-known, published interfaces, that effort could easily be split among many developers.
It turned out that not only could the same results be gained by all new code, but in some cases that code was better than the original UNIX versions. Because everyone could see the code being produced for the project, poorly written code could be corrected quickly or replaced over time.
If you are familiar with UNIX, try searching the hundreds of GNU software packages, which contain thousands of commands, for your favorite UNIX command from the Free Software Directory (https://directory.fsf.org/wiki/GNU). Chances are good that you will find it there, along with many, many other available software projects.
Over time, the term free software has been mostly replaced by the term open source software. The term free software is preferred by the Free Software Foundation, while open source software is promoted by the Open Source Initiative (https://opensource.org).
To accommodate both camps, some people use the term Free and Open Source Software (FOSS) instead. An underlying principle of FOSS, however, is that although you are free to use the software as you like, you have some responsibility to make the improvements that you make to the code available to others. This way, everyone in the community can benefit from your work, as you have benefited from the work of others.
To define clearly how open source software should be handled, the GNU software project created the GNU Public License, or GPL. Although many other software licenses cover slightly different approaches to protecting free software, the GPL is the most well known—and it's the one that covers the Linux kernel itself. The GNU Public License includes the following basic features:
Author rights: The original author retains the rights to their software.
Free distribution: People can use the GNU software in their own software, changing and redistributing it as they please. They do, however, have to include the source code with their distribution (or make it easily available).
Copyright maintained: Even if you were to repackage and resell the software, the original GNU agreement must be maintained with the software, which means that all future recipients of the software have the opportunity to change the source code, just as you did.
There is no warranty on GNU software. If something goes wrong, the original developer of the software has no obligation to fix the problem. However, many organizations, large and small, offer paid support (often in subscription form) for the software when it is included in their Linux or other open source software distribution. (See the section “OSI open source definition” later in this chapter for a more detailed definition of open source software.)
Despite its success in producing thousands of UNIX utilities, the GNU project itself failed to produce one critical piece of code: the kernel. Its attempts to build an open source kernel with the GNU Hurd project (https://gnu.org/software/hurd/) were unsuccessful at first, so it failed to become the premier open source kernel.
BSD loses some steam
The one software project that had a chance of beating out Linux to be the premier open source kernel was the venerable BSD project. By the late 1980s, BSD developers at University of California (UC), Berkeley realized that they had already rewritten most of the UNIX source code they had received a decade earlier.
In 1989, UC Berkeley distributed its own UNIX-like code as Net/1 and later (in 1991) as Net/2. Just as UC Berkeley was preparing a complete, UNIX-like operating system that was free from all AT&T code, AT&T hit them with a lawsuit in 1992. The suit claimed that the software was written using trade secrets taken from AT&T's UNIX system.
It's important to note here that BSD developers had completely rewritten the copyright-protected code from AT&T. Copyright was the primary means AT&T used to protect its rights to the UNIX code. Some believe that if AT&T had patented the concepts covered in that code, there might not be a Linux (or any UNIX clone) operating system today.
The lawsuit was dropped when Novell bought UNIX System Laboratories from AT&T in 1994. Nevertheless, during that critical period there was enough fear and doubt about the legality of the BSD code that the momentum that BSD had gained to that point in the fledgling open source community was lost. Many people started looking for another open source alternative. The time was ripe for a college student from Finland who was working on his own kernel.
NOTE
Today, BSD versions are available from three major projects: FreeBSD, NetBSD, and OpenBSD. People generally characterize FreeBSD as the easiest to use, NetBSD as available on the most computer hardware platforms, and OpenBSD as fanatically secure. Many security-minded individuals still prefer BSD to Linux. Also, because of its licensing, BSD code can be used by proprietary software vendors, such as Microsoft and Apple, who don't want to share their operating system code with others. MacOS is built on a BSD derivative.
Linus builds the missing piece
Linus Torvalds started work on Linux in 1991, while he was a student at the University of Helsinki, Finland. He wanted to create a UNIX-like kernel so that he could use the same kind of operating system on his home PC that he used at school. At the time, Linus was using Minix, but he wanted to go beyond what the Minix standards permitted.
As noted earlier, Linus announced the first public version of the Linux kernel to the comp.os.minix newsgroup on August 25, 1991, although Torvalds guesses that the first version didn't actually come out until mid-September of that year.
Although Torvalds stated that Linux was written for the 386 processor and probably wasn't portable, others persisted in encouraging (and contributing to) a more portable approach in the early versions of Linux.