pipe(PIPE_READ,PIPE_WRITE);
autoflush PIPE_WRITE 1;
my $pid = fork();
if ($pid = fork) {
  &write_pipe ($pid); 
  waitpid($pid,0); 
} 
elsif (defined $pid) {
  &read_pipe;         
}
else {
  die "cannot fork: $!";
}

sub write_pipe {
    print "pid $$ \n";
    print "Enter message: ";
    sleep 1;
    my $usr_msg = <>;
    print "Parent pid = $$  message = $usr_msg";
    print PIPE_WRITE "$usr_msg\n";
}

sub read_pipe {
    print "child pid = $pid";
    my $msg_read = <PIPE_READ>;
    
    print "received from pipe $msg_read";
}