....snip......
 # pipe1 - bidirectional communication using two pipe pairs
           #         designed for the socketpair-challenged

...snip.......

 But you don't actually have to make two pipe calls.  If you have the socketpair() system call, it will do this all for you.
 #!/usr/bin/perl -w
 # pipe2 - bidirectional communication using socketpair
 #   "the best ones always go both ways"