perldoc -f open with attention to the magic open, as in open(OUT, "|gpg ~/file.gpg") (might also be in perldoc perlipc) - but I suspect this won't work because things like gpg, when interacting with users, really want to talk with a terminal. At the very least you'll probably be dealing with Expect.pm, and the perl gpg modules may be unavoidable and/or less painful that what you'll go through trying to avoid them.

--Bob Niederman, http://bob-n.com