Business leaders like Ransom Love, chief executive of Caldera, might say that revenues are the way forward for GNU/Linux, but Richard Stallman is having none of it. Linux is moving slowly but surely into the mainstream, taking over significant market share in servers and receiving the backing of blue-chips like IBM, who want open source, "free" software and proprietary software to coexist. But in a recent interview with ZDNet Germany, Stallman, founder of the Free Software Foundation and initiator of the Unix-like GNU operating system project, reminded the business world that he remains deadset against "non-free" software. Stallman has been credited with creating the wave of open source or free software that has made Linux Microsoft's number one enemy. He launched the GNU ("GNU's Not Unix") project in 1984 to create a freely-distributable version of Unix, the networking operating system used by telcos and high-end Web servers. In the 1990s, programmers began using a version of GNU with the Linux core, known as GNU/Linux. Following the success of GNU/Linux, the Open Source Foundation was created in 1998 to promote a new model of software development in which programmers could freely alter and redistribute operating systems and applications. But "open source", as a development model, is a much looser term than Stallman's "free software" idea. What's important to the FSF is that software should not be bound up in proprietary licences -- the GNU Public Licence (GPL) and others require that any alterations to source code must be made available to other developers. But some "open source" software, such as BSD, does not make such stringent requirements; Microsoft has made use of BSD code in its products and Apple's OSX is based on BSD. (See also: "Free software and fundamentalism".) That is where Stallman and open source differ. "The open source movement and the free software movement are rivals, not enemies. I disagree with the open source movement, and it's a mistake to say I support it, but I'm not against it either," Stallman told ZDNet Germany. "We, the project that developed GNU, reject the term 'open source'. We disagree with the open source movement, and we have never agreed with it. We are not part of it," Stallman said. Microsoft has recently attacked the GPL as an enemy of intellectual property and therefore of free enterprise. Companies like Caldera and IBM, on the other hand, argue that it's possible to find a middle ground where proprietary software can work with GPL-based "free" software. Stallman is against both arguments, and he called Caldera's Love a "parasite" in one conversation with ZDNet. "My criticism was specifically against Caldera, because of its development of programs that are not free," he elaborated. "Those programs are not open source either. Ransom Love's support for free software is just lip service." Love's response to Stallman is: "We add value to Linux, so it can become successful." But the Free Software Foundation chairman says Love's orientation is fundamentally at odds with what GNU/Linux is all about. "When Love says 'Linux', he is talking about a version of the GNU operating system, with Linux as the kernel," he said. "So he claims to be making GNU more successful. But what results does it really lead to? The purpose of GNU is to give users freedom -- GNU is a success if it gives freedom to many people. "When Caldera adds Caldera's non-free software to the GNU/Linux system, that system no longer gives freedom to its users. The GNU system as distorted by Caldera can't possibly achieve its purpose. What success could it have?" he asked. Of course, Love is arguing as a businessman, while Stallman is a dyed-in-the-wool idealist, and the free-software founder leaves little hope that there could be a common ground. "I understand Ransom Love -- he is not the first businessman try to claim that his profit justifies mistreatment of others," Stallman told ZDNet. "When the environmental movement began, the owners of factories that poluted the air and the water said the same thing: 'We're not trying to hurt anyone, we're just trying to make money.' Non-free software pollutes society's most important resource, the spirit of cooperation and goodwill towards other people. This psychosocial resource is vital for a good society, just as clean air and clean water are vital." Love argues that, in fact, the ultimate benefit that can come to GNU/Linux is profits, something that Stallman says he can never accept. "We must recognise that companies developing non-free software that works with GNU/Linux are not contributing to the system or to our community," he said. "Instead, they are trying to distract people and lead them away from freedom. Their 'investment' is like building a factory designed to pollute the air. It does harm, not good, to our community." Find out how the open source movement is revolutionising the high-tech world at ZDNet UK's Linux Lounge. Have your say instantly, and see what others have said. Click on the TalkBack button and go to the Linux lounge forum Let the editors know what you think in the Mailroom. And read other letters.