socketpair

socketpair 
sock1
, 
sock2
, 
domain
, 
type
, 
prtcl

Creates an unnamed pair of sockets in the specified domain and of the specified type . domain , type , and protocol are specified the same as for socketpair(2) . If socketpair is unimplemented, invoking this function yields a fatal error. The function returns true if successful.

This function is typically used just before a fork . One of the resulting processes should close sock1 , and the other should close sock2 . You can use these sockets bidirectionally, unlike the filehandles created by the pipe function.