IIRC #! originated at Bell Labs but it got out to the
world via BSD.
Perhaps Dr. McIlroy could confirm / deny / expand upon the details (please?)
I recall Dennis discussing the feature at some length before installing it.
So the exact semantics, especially the injected argument, are almost]
certainly his. I don't know whether he built on a model from elsewhere.
#! appeared between v7 (1979) and v8 (1985). As v8 was never released,
it clearly made its way into the world via BSD and USG. BSD, being
more nimble, was likely first.
doug