An oft-asked question is basically, "What do SCO think they're doing?"

I can't say when they started, but the plan was to repeat the success of the DR-DOS Microsoft case. Caldera obtained the rights to DR-DOS in 1996, and in the same year brought a suit against Microsoft for unfair competition, which was settled in 2000 for an estimated $150 million

news story

That is quite a pattern: buy a product which is obsolete and going cheap, and sue a major IT player for impairing its value.

Caldera effectively bought SCO Unix with the money it received from MSFT in the DR-DOS settlement!

Caldera buy SCO Unix

I don't think Linux was at all a central part of SCO's strategy. AIX was the target, as IBM was to play the part of Microsoft in a replay of the DR-DOS case. The big initial threat SCO went in with was the termination of IBM's Unix license.

The thinking went:

1. Use UNIX rights to sting IBM
2. How? Find some pretext to yank IBM's license for AIX
3. What pretext? Oh, say they leaked code into Linux.

Remember SCO's early statements were that they weren't going after Linux users or distributors, their beef was with IBM and AIX. I believe this reflected their initial strategy.

Quote from March 2003 Caldera press release:

Caldera press releases

"The complaint alleges that IBM made concentrated efforts to improperly destroy the economic value of UNIX, particularly UNIX on Intel, to benefit IBM's new Linux services business."

Again, this echoes the MSFT anti-trust suit far more than any claim over Linux code.

For some reason, they got rattled and changed approach. I'm not sure why. They should not have been shaken by IBM's choosing to fight; after all, it took them four years to screw their settlement out of MSFT.

For whatever reason, every step they took after that point looks hurried, desperate, and ill-thought-through. The facts that they seemed ignorant of the terms of the GPL, and of their own release of the 32V code under a BSD license, indicates that they hadn't done any homework on the issues.

The mode of thought behind these ill-considered maneuvers is quite a common one: you get carried away with the possible gains from a course of action and simply forget to weigh up the odds or estimate the possible downside. I think SCO, rattled for some reason, waved around for new angles they could find and rushed ahead with a disastrous course of action like medieval cavalry pursuing a beaten enemy off the battlefield.

The last question is what rattled them and threw them off their original plan. I really don't know, but here are three suggestions:

1. IBM's response to the suit was much stronger legally than they expected
2. They were expecting a sympathetic "David vs Goliath" press background similar to the one they had in the DR-DOS case, and were taken aback by the opposition coming from the Open Source movement. This theory has the recent "IBM is out to get us" ranting to back it up.
3. They just saw the Linux attack as a great opportunity they hadn't really considered, and charged ahead thoughtlessly.

I'm really open to other suggestions, because that's the best I can do on this question.