popen(3) is indeed available in Perl. It's just spelled o-p-e-n. Your standard open with a vertical bar at the beginning or the end maps to popen, effectively. And as I recall, the standard popen(3) was also one way or the other, and not both ways as you wanted.

So you wanted something beyond popen that does bidirectional opens. And the other messages in this thread are describing them to you, so I won't repeat that.

-- Randal L. Schwartz, Perl hacker