Question

Its a simple Perl socket server. It listens for commands on a given port, and executes an applescript if the command is ‘play’. There are two problems with the code below.

1. Once the ‘play’ command is executed, both the client and the server are closed. (I want the server to continue listening for commands, be it ‘play’ or otherwise)
2. The sockets don’t unbind. (I have to change the port number everytime I reuse it)

I’m using Terminal on a mac to execute the perl script, and telnet via terminal on another mac to trigger it.

#!/usr/bin/perl -w 
use warnings;
use IO::Socket; 
use Net::hostent;

$PORT = 8000;

    $server = IO::Socket::INET->new( Proto     => 'tcp',
                                     LocalPort => $PORT,
                                     Listen    => 5,
                                     Reuse     => 1) or die "can't setup server" unless $server;

    print "SERVER Waiting on port $PORT\n";

    while ($client = $server->accept()) { 
        $client->autoflush(1); 
        print $client "Command:\r\n";

        while (<$client>) {
            if (/play/i) { 
                exec("osascript '/Users/user/Desktop/play.app'");
            } else {
                print $client "invalid command\r\n";
            } 
        } continue { 
                        print $client "Command: "; 
        } close $client; 
    }

Answer 1

You are using exec. From perldoc -f exec

The exec function executes a system command and never returns; use
system instead of exec if you want it to return. It fails and returns
false only if the command does not exist and it is executed directly
instead of via your system’s command shell (see below).

Since it’s a common mistake to use exec instead of system, Perl warns
you if there is a following statement that isn’t die, warn, or exit
(if -w is set–but you always do that, right?). If you really want to
follow an exec with some other statement, you can use one of these
styles to avoid the warning:

This basically means that your socket closes, because the perl script exits. I assume this leaves the ports blocked because the socket is never explicitly or implicitly closed.