> My perception is that srfi-170 corresponds to POSIX.1 (excluding some
> subdomains that are to be other srfis).   "mkdir -p" is not POSIX.1; it
> is POSIX.2.

Are these POSIX.n numbers explained somewhere, and do they have listings
of what was added to each standard?

> It won't be expensive itself, but if we start including such utilities
> above POSIX.1 layer, I'm afraid that the boundary of what to include
> gets blurred.  For example, if we have "mkdir -p", then why not "rm -r" ?

True. Python has a shutil module for the kind of thing.
<https://docs.python.org/3/library/shutil.html>

Though they put makedirs() in the os module
<https://docs.python.org/3/library/os.html#os.makedirs>.

I suggest we do the same. makedirs() is so often needed that people keep
writing lots of subtly incorrect implementations of it.