I only need to say why if I send a message terminated by a 
new-line the server read the message , without the new-line 
I got no answer.


If the server is something like this :
 while( 1 )
 {
    my $new_sock = $sock->accept();
    $stmp = <$new_sock>;
    print "$stmp";
    print $new_sock "$stmp\n";
    close($new_sock);
 }
 close($sock);

the server hang waiting for a newline.
what cha I do to avoid the server waiting for the newline.

You cannot use <$new_sock> anymore, because that waits for a newline character. You need to use read instead. You also likely want nonblocking IO using the four-argument version of select. Likely, IO::Select wraps this up nicely for you. There is example code on how to use IO::Select in its documentation. For select, I didn't find any nice documentation.

Basically, select and IO::Select return once a socket is ready to receive more data or to send more data, and tell you which socket(s).

There are three multiplexing frameworks I know of that handle nonblocking sockets in a manner that is more or less inconveniencing - POE, Danga::Socket and Coro. All three have different uses and different shortcomings.

read is not ok, because is mapped on fread instead I used sysread.

I replaced the statemente :$sres = <$new_sock>; with the following code:

(mybe it should be helpfull to someone else )

    $rin="";
    $sres = "";
    vec($rin,fileno($new_sock),1) = 1;
    $nfound=select( $rin, undef, undef, .1 );
    while ( $nfound )
    {
          sysread( $new_sock, $c, 1 );
	  chomp $c;
	  $sres .= $c;
          $nfound=select( $rin, undef, undef, .1 );
    }