Context is conversations where people assume that POSIX is the spec for Unix, and some other OS is POSIX, so just re-compile already... or hey, we won't have to

Context is conversations where people assume that POSIX is the spec for Unix, and some other OS is POSIX, so just re-compile already... or hey, we won't have to rewrite a lot of tooling for some other OS because we used POSIX OS... or it will just magically run because POSIX. Incidentally, a ton of GNU utilities aren't POSIX unless you set the POSIXLY_CORRECT environment variable...