Thanks for all your replies. I should have mentioned that in my case child has been forked already and now I wish to communicate with specific. need Child to Child communication. kindly check the comment section below Suggestion for alternate approach is most welcome as well.

 
sub make_new_child {
 # Make new child...
    my $pid;
    my $sigset;
    # block signal for fork
    $sigset = POSIX::SigSet->new(SIGINT);
    sigprocmask(SIG_BLOCK, $sigset)
        or die "Can't block SIGINT for fork: $!\n";
    die "fork: $!" unless defined ($pid = fork);
    
    if ($pid) { 
        # Parent records the child's birth and returns.
        sigprocmask(SIG_UNBLOCK, $sigset)
            or die "Can't unblock SIGINT for fork: $!\n";
        print "PID $pid\n" if $Debug;
        $children{$pid} = 1;
        $children++;
        return;
    } else {
        print "Child....\n" if $Debug;
        $SIG{INT} = 'DEFAULT';      # make SIGINT kill us as it did be
+fore
        my $request = "";        # full long big request
        my $nreads    = 0;        # number of read loops
        my $tmout     = 150;    # timeout in second
   
        # unblock signals
        sigprocmask(SIG_UNBLOCK, $sigset)
            or die "Can't unblock SIGINT for fork: $!\n";
    
        # handle connections until we've reached $MAX_CLIENTS_PER_CHIL
+D
        for (my $i=0; $i < $MAX_CLIENTS_PER_CHILD; $i++) {
        #    my $device="";
           print "New connection....\n" if $Debug;
            my $client = $Socket->accept()     or last;
            $client->autoflush(1);
            ($Debug && $client) ? print "Accepted....\n" : print "No S
+ignal Recieved\n";
            # do something with the connection
            my $sel = IO::Select->new($client);            

            while ( $sel->can_read($tmout) )
            {
                    my $n = sysread($client, $request, 9999,length($re
+quest));
                    last if ($n==0);
                    $nreads++;
                    my $display = "";

                    if ( $nreads == 0 ) {
                            $display = '[timeout]';
                    } elsif ( length $request == 0 ) {
                            $display = '[empty]';
                    } else {
                            $display = $request;
                    }
                    $request="";
                    print "$display\n" if $Debug;
                    my @data = split(/,/,$display);
                    if($data[0] eq '!!'){
                            # A command
                            ####
                            ####Received the command here to send it t
+o child PID 123
                            ###### child PID 123 has been already fork
+ed and free 
                            ###### to serve this request
                            print "A command, Lets send\n";
                            my $to_pid = $data[1];
                            my $command = $data[2];#__________________
+___________________________________________________
                            #
                            # Lets send command to $to_pid from here
                            #_________________________________________
+____________________________

                            # qx (echo e)

                            print CHLD_IN "$command $pid  sent from $p
+id \n";

                            #print FHY ("OK, Lets Send coand\n");
                            sleep(3);

                    } else {
                    }
            }
        }
       exit(0);
    }
}
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