Earlier quoted context omitted.
It wasn't a coincidence, or an accident. C was specifically designed to write Unix, by people who had experience with a lot of other computer languages, and had programmed other operating systems including Multics and some earlier versions of Unix. They knew exactly what they were doing, and exactly what they wanted.
I'm not sure what you mean by "coincidence" or "accident" here. C is a pretty OK language for writing an OS in the 70s. UNIX got popular for reasons I think largely orthogonal to being written in C. UNIX was one of the first operating systems that was widely licensed to universities. Students were obliged to learn C to work with it. If the Macintosh OS had come out first and taken over the world, we'd probably all be…
From page 52:
> Operating systems have to deal with some very unusual objects and events: interrupts; memory maps; apparent locations in memory that really represent devices, hardware traps and faults; and I/O controllers. It is unlikely that even a low-level model can adequately support all of these notions or new ones that come along in the future. So a key idea in C is that the language model be flexible; with escape hatches to allow the programmer to do the right thing, even if the language designer didn't think of it first.
This. This is the difference between C and Pascal. This is why C won and Pascal lost - because Pascal prohibited everything but what Wirth thought should be allowed, and Wirth had far too limited a vision of what people might need to do. Ritchie, in contrast, knew he wasn't smart enough to play that game, so he didn't try. As a result, in practice C was considerably more usable than Pascal. The closer you were to the metal, the greater C's advantage. And in those days, you were often pretty close to the metal...
Later, on page 60:
> Much of the C model relies on the programmer always being right, so the task of the language is to make it easy what is necessary... The converse model, which is the basis of Pascal and Ada, is that the programmer is often wrong, so the language should make it hard to say anything incorrect... Finally, the large amount of freedom provided in the language means that you can make truly spectacular errors, far exceeding the relatively trivial difficulties you encounter misusing, say, BASIC.
Also true. And it is true that the "Pascal model" of the programmer has quite a bit of truth to it. But programmers collectively chose freedom over restrictions, even restrictions that were intended to be for their own good.