To "continuously run"; you need to make your program either a service or a a daemon. Which depends upon what OS you are using.

How do I script Perl to continuously run?

Avoid any terminating statements such as exit or die, handle all signals, wrap any calls which may cause termination in eval (or use one of the try/catch modules), ensure you don't exhaust the limited resources of the hardware or the limits assigned to the process by the O/S. If using threads, ensure everything is thread-safe. If you do all that and your script still fails to run continuously then you'll need to provide some more detail.

Welcome to the Monastery, avatarengineer!

Can you describe in a bit more detail as to what you're trying to achieve? Are you wanting to write a script that can listen on multiple ports, and write/log information if those ports are touched? Or are you wanting to develop something that tries to 'see' when existing listening services receive requests and then logging that?

Beyond that, can you share what you've tried so far, or at minimum, show what/where you've researched?

-stevieb

Hi, that's no problem, see this link.

Please don't use URL-shorteners, especially not lmgtfy. This is not the tone I want used for newcomers. Also, if somebody asks what to you seems like a very basic question, most likely they also lack the ability to judge the quality of the links found through a search engine. Please, when linking to a search query, also point out two or three relevant links from the results and maybe even explain what to find in them or why that's relevant.

This seems to work:

use warnings;
use strict;
use IO::Socket;

my $socket = new IO::Socket::INET (
    LocalHost => 'localhost',
    LocalPort => '8888',
    Proto => 'tcp',
    Listen => 1,
    Reuse => 1,
);
die "Could not create socket: $!\n" unless $socket;

$|++;
while (1) {
    my $incoming = $socket->accept();
    while(<$incoming>) {
        print $_;
    }
    print "\nNext session.\n";
}

close($socket);
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Here is how I run it as a daemon in Unix:

$ nohup ./listen.pl >listen.log 2>listen.log &
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After it is running, here I am testing it out:

$ telnet localhost 8888
Trying ::1...
telnet: connect to address ::1: Connection refused
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
You there?
^]
telnet> quit
Connection closed.
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And here is the output showing up in my log:

$ cat listen.log 
You there?

Next session.
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And here is the process still running afterwards.

$ jobs
[1]+  Running    nohup ./listen.pl > listen.log 2> listen.log &
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