Unix (Cygwin) whatis: returns all commands as "nothing appropriate"

I ran into a similar issue using the 64-bit Red Hat Cygwin installation.

In my case, /usr/sbin/makewhatis did not exist. Running man and a command worked, but neither apropos nor whatis returned anything other than "nothing appropriate".

After searching for a missing package and binging a bunch, I Read The Friendly Manual page for man and found out about mandb.

Running mandb solved my problem.

From the Cygwin FAQ:

Why doesn't man -k (or apropos) work?

Before you can use man -k or apropos, you must create the whatis database. Just run the command

mandb

(it may take a minute to complete).

(Note: It used to say /usr/sbin/makewhatis instead of mandb in older versions of that FAQ.)

Run sudo mandb once

Not sure if this helps, but when I ran mandb, I got this (over several attempts).

mandb    0 man subdirectories contained newer manual pages.0 manual pages were added.0 stray cats were added.0 old database entries were purged.

However,

sudo mandb75 man subdirectories contained newer manual pages.7235 manual pages were added.0 stray cats were added.0 old database entries were purged.

worked for real.