GNU/Linux is getting seriously successful. Every month brings high-profile corporate converts to the free operating system's combination of low-cost power, flexibility, security and stability. Newcomers to the penguin appreciation club include Unilever, Oracle and Dell. Meanwhile, increasing numbers of manufacturers are adopting it for non-computer products: for example, at the beginning of July, eight leading consumer electronics (CE) companies - Hitachi, Matsushita, NEC, Philips, Samsung, Sharp, Sony and Toshiba - set up the CE Linux Forum to "promote broad usage of Linux for CE products".
The US Department of Energy's next-generation supercomputer project Red Storm (capable of several hundred thousand billion computations per second) has joined IBM's Blue Gene (a million billion operations per second) in using GNU/ Linux as the core operating system. For those who need something cheaper - IBM's Blue Gene will cost around $100m - the National Center for Supercomputing Applications at the University of Illinois has an alternative: a top-flight number cruncher built from a cluster of 65 Sony PlayStation2s running GNU/Linux.
Perhaps more important in the long run are developments at the other end of the computing spectrum. For the first time, open source suppliers like SuSE and Ximian have brought out products aimed at the corporate desktop. The decision by the city of Munich to replace Windows by GNU/Linux on 14,000 computers was a propaganda blow to Microsoft. Similarly, the announcement by the Spanish regional government of Extremadura that it has put 80,000 computers running only open source into its schools is a significant straw in the wind.
Success in the business and education markets also prepares the way for GNU/Linux's triumph in the home sector. The natural reluctance of high-street chains to take a chance on relatively unconventional offerings means the consumer market is likely to be Windows' last bastion. But once enough people have become familiar with the benefits of open source, the emerging market for end-user products will be too attractive for major outlets to ignore.
Nor are the Europeans alone in moving away from proprietary systems: the advantages of open source are particularly compelling for developing countries unable to afford massive licensing fees for nationwide roll-outs of proprietary programs. As the president of India said in May: "Open source code software will have to come and stay in a big way for the benefit of our billion people."
Finally, two academics studying "software bug dynamics" have demonstrated that "for a given set of parameters, debugging in open source projects is always faster than in closed source projects." No wonder Steve Ballmer, Microsoft'schief executive, devoted much of a recent memo to his troops warning of the challenge from what the Seattle giant is now trying to stigmatise as "non-commercial software" - even though the term is manifestly inaccurate in the face of growing sales of GNU/Linux systems by leading companies such as IBM and HP.
And yet, just when everything seemed to be going so well, GNU/Linux is facing its potentially most damaging attack, and from an unlikely quarter: a company that has done much to help make GNU/Linux a viable business solution.
Caldera was set up in 1994 to produce a business-oriented version of GNU/Linux, at that time very much a hacker's system. One important move was to acquire the rights to the Unix operating system from the company SCO in August 2000. GNU/ Linux was largely modelled on Unix, and so this seemed to ensure there would be no legal problems in terms of intellectual property issues - always a danger while Unix was owned by a company competing with the open source operating system.
Despite its many contributions to the GNU/Linux world, Caldera never enjoyed the same kind of success there as Red Hat, for example. As a result, new management decided to take a different tack. Renaming the company as SCO in August 2002 signalled a new focus on the Unix side of the business. This culminated on March 7 in the filing of a lawsuit against IBM alleging "misappropriation of trade secrets, tortious interference, unfair competition and breach of contract", and requesting damages "no less than $1bn".
What was particularly surprising given its pedigree was the way that Caldera/SCO brought GNU/Linux into the equation, alleging that "IBM made concentrated efforts to improp erly destroy the economic value of Unix, particularly Unix on Intel, to benefit IBM's new Linux services business." The formal complaint is even more explicitly anti-Linux: "Prior to IBM's involvement, Linux was the software equivalent of a bicycle. Unix was the software equivalent of a luxury car."
Not content with belittling the developers of Linux, in May, SCO warned them and users that "Linux is an unauthorized derivative of Unix and that legal liability for the use of Linux may extend to commercial users". In July, SCO alleged that hundreds of files of misappropriated Unix source code and derivative Unix code have been contributed to Linux in a variety of ways", causing "customers to use a tainted product at SCO's expense". Its chief executive, Darl McBride, added ominously that "we expect SCO to be compensated", and offered GNU/Linux users a special licence to its UnixWare product.
IBM and the Linux community have responded with relative equanimity. IBM has simply said it will defend itself "vigorously", while Linux hackers have crafted detailed rebuttals of SCO's charges where they are concrete enough to be discussed sensibly.
One positive outcome may be the introduction of a little more rigour into the open source development process. As Eric Raymond, the leading theoretician of the movement, says: "We might see a little more energy put into recording the origin of patches" - the new lines of code. But there are limits to what can be done. "The problem," he notes, "is that all the changes I can imagine would both (a) impose an unacceptably high amount of additional process overhead, and (b) not actually guarantee us protection from lawsuits."
Caldera/SCO's extraordinary U-turn marks a key moment in the rise of GNU/Linux. It is interesting that Linus Torvalds, the creator of Linux, announced in June that he was taking leave of absence from the start-up company Transmeta, where he has worked for the last six years, to spend some time at the industry-funded Open Source Development Lab, "finally actually doing Linux as my main job", as he put it. Hitherto, Linux has remained spiritually close to the "hobby" he first announced in August 1991: work done alongside something else - first his studies at Helsinki University, then his Transmeta position. Now, it seems, even Linus recognises that it's time to get serious.
· Glyn Moody is the author of Rebel Code: Linux and the open source revolution.
