Perl5 リファレンス

               Creates an unnamed pair of sockets in the
               specified domain, of the specified type.  DOMAIN,
               TYPE, and PROTOCOL are specified the same as for
               the system call of the same name.  If
               unimplemented, yields a fatal error.  Returns true
               if successful.

               On systems that support a close-on-exec flag on
               files, the flag will be set for the newly opened
               file descriptors, as determined by the value of
               $^F.  See the section on "$^F" in the perlvar

               Some systems defined `pipe' in terms of
               `socketpair', in which a call to `pipe(Rdr, Wtr)'
               is essentially:

                   use Socket;
                   socketpair(Rdr, Wtr, AF_UNIX, SOCK_STREAM, PF_UNSPEC);
                   shutdown(Rdr, 1);        # no more writing for reader
                   shutdown(Wtr, 0);        # no more reading for writer

               See the perlipc manpage for an example of
               socketpair use.