sh: getting <category>/<portname> from pwd

Hello all,

I'm writing a shell script to feed poudriere testports and I need to get
<category>/<portname> from ports tree:

`pwd`:
/home/user/work/freebsd/ports/<category>/<portname>

`pwd | rev | cut -d / -f1,2 | rev` do the trick but it is so uggly!

Is there a shell option to get it?

Thanks,
-- 
Nuno Teixeira
FreeBSD Committer (ports)