Full text search for man pages
By using the command man man we can see that we have two options.
-k Equivalent to apropos.
-K Search for the specified string in *all* man pages. Warning:
this is probably very slow! It helps to specify a section.
(Just to give a rough idea, on my machine this takes about a
minute per 500 man pages.)
This is on a RHEL 5 system
This is probably late. But I just completed my Google Summer of Code project for NetBSD and my task was exactly this. Implementing full text search for man pages.
The code is here: https://github.com/abhinav-upadhyay/apropos_replacement
Although at the moment this is for only *BSD (NetBSD to be precise but should work with other BSDs with some small adjustments) systems due to some assumptions made while writing the code and I don't have a Linux machine around me to fix or port this for working on Linux.
There is a web interface available for it at man-k.org