[nibbula]

We can call whatever we want Lisp. And everyone does. McCarthy, wisely, didn't want people to bicker over this. But it would be a reasonable assumption that by Lisp, one meant Common Lisp.

I'm not sure what you're getting at with exit(2). The CL standard does not include an exit function, because it would be limiting. For example the meaning of exit for an operating system is unclear. But most implementations include a simple exit function. You can do what exit does, more simply in CL than in C, using unwind-protect. You can use the FFI built in to every implementation to write an exit that exactly duplicates what the C stdlib exit(3) and _exit(2). With a very small set of macros, it is portable to all CL implementations. You can even execute the processor abort instruction if it has one. But of course you can't do that portably. But exit written in C is not actually portable, but only looks that way due to a bunch macros.