I'm trying to make a communication between 2 computers with different 
operating systems, for example the server uses SCO and the client uses Red 
Hat. 
I want the client send some data information to the server and after the 
sending process is done, then the server executes the data. So, I combine 
Perl and Shell script to executes the data.
However, I got problem with this combination. Everytime after the data is 
sent, then the server executes my shell codes twice and this causes an 
error.
I don't know much about socket programming, so please correct me if I'm 
wrong.
Here is my perl script:

#!/usr/local/bin/perl 

use Socket;
use Shell;
use IO::Handle;

sub my_lock 
{
   socket(SOCK, AF_INET, SOCK_STREAM, getprotobyname('tcp')) 
       or die "Cannot create socket: $!";
   return(1) if
       bind(SOCK, sockaddr_in(9999, inet_aton("localhost")));
   if ($! !~ /already/i)
   {
     return;
   }
  0;
}
sub my_unlock
{
  close(SOCK);
}
  
socket(SOCK, AF_INET, SOCK_STREAM, getprotobyname('tcp')) || die;
bind(SOCK, sockaddr_in(9999, INADDR_ANY)) || die "$!";
listen(SOCK, SOMAXCONN) || die "Listen failed: $!";

print "Waiting ... \n";
while ( accept(NEWSOCK, SOCK) ) 
{
   shutdown(NEWSOCK, 1);
   SOCK->autoflush(1);
   $pid = fork();
   die "Cannot fork: $!" if (!defined $pid);

   if($pid) {
     close(PARENT);
     print "I'm the parent, process ID $$.
            My child is $pid\n";
   } else {
     close(CHILD);
      print "I'm the child. My PID is $$.\n";
   }

   $a=<NEWSOCK>;
   my_lock();

   close(NEWSOCK);
   # Run the shell script applicant3.c

   print "GOTO /usr/mike ... \n";
   cd ("/usr/mike");
   exec $a;
   print "Done ... \n";
   my_unlock();
}

and here is my shell script:

PATH=$PATH:/u/appgen5/bin; export PATH
AGHOME=/u/appgen5; export AGHOME
cd /u/appgen5/TP

applicant3 $*

Can anyone help me?
Thanks.