How to open grep(1p) manpage

grepmanposix

At the end of man grep, it says

SEE ALSO\ 
   POSIX Programmer's Manual Page
       grep(1p).

I am not able to open the manpage grep(1p). How do I do that? Search net, Unix.SE and did trial and error but no luck yet.

Tried

$ man 1p grep
$ man -K grep

EDIT:

I am on Ubuntu 14.10

1P is an extension to 1 man page of grep. You can use man -e P grep to get P extension manual page(man -e 1p grep should also work).

There is also other way: man -a grep shows all man pages for grep, so you can skip unnecessary pages manually, and go to 1P.

You also may want to learn how to use man - man man will get you there(yes, man has its own man page).

edit: In case you don't have mentioned man pages, if you're using Ubuntu or Debian, you might want to install manpages-posix-dev:

sudo apt-get install manpages-posix-dev