"AT&T tried to sue everybody who had any dialect of Unix."
Perhaps. They started with BSD (http://en.wikipedia.org/wiki/USL_v._BSDi), suing the initial commercial BSD vendor and the university proper. They utterly lost when it was shown they hadn't followed the BSD license with BSD code they'd incorpated in their own versions, that had been licensed to others and that were used for their own operations (they were thrown a face saving bone in the settlement that required a relative handful of BSD files to be re-written, but were otherwise skunked).
I'm not sure why they stopped doing this, although it's telling that Novell bought UNIX(TM) in the middle of the year in which AT&T settled with Berkeley.
Perhaps. They started with BSD (http://en.wikipedia.org/wiki/USL_v._BSDi), suing the initial commercial BSD vendor and the university proper. They utterly lost when it was shown they hadn't followed the BSD license with BSD code they'd incorpated in their own versions, that had been licensed to others and that were used for their own operations (they were thrown a face saving bone in the settlement that required a relative handful of BSD files to be re-written, but were otherwise skunked).
I'm not sure why they stopped doing this, although it's telling that Novell bought UNIX(TM) in the middle of the year in which AT&T settled with Berkeley.