Free minix-like kernel sources for 386-AT, was the subject of Linus Benedict Torvalds post to comp.os.minix on October 5, 1991 -- seventeen years ago today.

it began,

Do you pine for the nice days of minix-1.1, when men were men and wrote their own device drivers? Are you without a nice project and just dying to cut your teeth on a OS you can try to modify for your needs? Are you finding it frustrating when everything works on minix? No more all-nighters to get a nifty program working? Then this post might be just for you :-) As I mentioned a month(?) ago, I'm working on a free version of a minix-lookalike for AT-386 computers. It has finally reached the stage where it's even usable (though may not be depending on what you want), and I am willing to put out the sources for wider distribution. It is just version 0.02 (+1 (very small) patch already), but I've successfully run bash/gcc/gnu-make/gnu-sed/compress etc under it.

Linus didn't know what he was unleashing with "an OS you can try to modify to your needs" -- yet. But what started as a fun vetting of one *nix became the largest barn-raising in the history of computing. (By the way, i remembered this date while on another hunt for information, in Encyclopedia Brittanica, where today Linux' birthday is the Home Page story. Oddly, it fails to get a mention in today's Wikipedia cover page.)Today that barn is vast world still being terraformed. Why did Linux succeed where others did not, or did to lesser extents?

I think Neal Stephenson nails it best in his landmark book, In the Beginning Was The Command Line, the whole text of which you can read here. Written in the late 1990s, it still rings true today. A core sample:

Windows 95 and MacOS are products, contrived by engineers in the service of specific companies. Unix, by contrast, is not so much a product as it is a painstakingly compiled oral history of the hacker subculture. It is our Gilgamesh epic. What made old epics like Gilgamesh so powerful and so long-lived was that they were living bodies of narrative that many people knew by heart, and told over and over again--making their own personal embellishments whenever it struck their fancy. The bad embellishments were shouted down, the good ones picked up by others, polished, improved, and, over time, incorporated into the story. Likewise, Unix is known, loved, and understood by so many hackers that it can be re-created from scratch whenever someone needs it. This is very difficult to understand for people who are accustomed to thinking of OSes as things that absolutely have to be bought. Many hackers have launched more or less successful re-implementations of the Unix ideal. Each one brings in new embellishments. Some of them die out quickly, some are merged with similar, parallel innovations created by different hackers attacking the same problem, others still are embraced, and adopted into the epic. Thus Unix has slowly accreted around a simple kernel and acquired a kind of complexity and asymmetry about it that is organic, like the roots of a tree, or the branchings of a coronary artery. Understanding it is more like anatomy than physics. For at least a year, prior to my adoption of Linux, I had been hearing about it. Credible, well-informed people kept telling me that a bunch of hackers had got together an implentation of Unix that could be downloaded, free of charge, from the Internet. For a long time I could not bring myself to take the notion seriously. It was like hearing rumors that a group of model rocket enthusiasts had created a completely functional Saturn V by exchanging blueprints on the Net and mailing valves and flanges to each other. But it's true. Credit for Linux generally goes to its human namesake, one Linus Torvalds, a Finn who got the whole thing rolling in 1991 when he used some of the GNU tools to write the beginnings of a Unix kernel that could run on PC-compatible hardware. And indeed Torvalds deserves all the credit he has ever gotten, and a whole lot more. But he could not have made it happen by himself, any more than Richard Stallman could have. To write code at all, Torvalds had to have cheap but powerful development tools, and these he got from Stallman's GNU project.

Yet for all of the successes of LInux and the Net, of half a million open source projects, of immeasurable progress by companies taking advantage of sturdy building material grown in the wilds of hacker culture, businesses still remain, as Walt Whitman so perfectly put it, "demented with the mania of owning things". Nine years have passed since Jeremie Miller introduced XMPP (then still Jabber), and Yahoo, Microsoft and AOL still maintain closed instant messaging systems. Mobile phone companies and equipment providers still make devices and platforms that are purposely incompatible with those of competitors. Companies still look for ways to use software hardware/software combinations to "lock in" their customers, as if slavery were something any sane customer would want.

There are signs of progress, as there always will be, until World Domination (a term that showed up more than a decade ago) is complete. Until Google introduced the Linux-based Android, Linux-based mobile phones were nearly (or just as) closed as those from Symbian and Windows Mobile. But Nokia bought Linux developer Trolltech in January and Symbian in July -- and then announced its intent to open-source the latter.

Nokia knows that a free customer is better than a captive one. And that the same goes for developers.