I want to find all man pages for commands that begin with wh. But I do not understand why the following keyword does not work.

  man -f "wh"

Also if I put

  man chmod

in man page of chmod, it has the word "symbolic", so I put

  man -f "symbolic"

but chmod command does not show up in the results.

In short, how do I find/search commands or command description by inside-word contents? I know how to find a certain words after I get the man page, using / character, but I want to find all man pages with the search word.