bug#3717: M-x man completion

[Kevin Ryde]

Eli Zaretskii <eliz@gnu.org> writes:
>
> It could be, but it also isn't universally available, especially if
> you are on a non-Posix platform.

I see V7 doesn't have either :-)

    http://plan9.bell-labs.com/7thEdMan/index.html

but that -k is in posix (and specified as an ERE regexp, answering a
comment Stefan put),

    http://www.opengroup.org/onlinepubs/009695399/utilities/man.html

> Ideally, `man' should test what's available, like `grep' does, and if
> nothing is, simply not provide this feature.

I'd be open to ideas for my code at least, as long as it's not merely
defunct cp/m derivatives where there's a potential problem :).