You are looking at a very old, but free version of the course. If you are interesed the most recent version, check it out on the Perl Maven site.

10.2. Connect to the device

Setting both Dump_log and Input_log in the constructor of Net::Telnet 
will allow us to see what is really going on on the connection.

We also add a call to wait for something that is likely won't show up
in the output. Depending on where the demo application (the daemon)
is running you might need to change the $hostname variable.

Example 10-1. examples/cli/cli_01.pl

#!/usr/bin/perl
use strict;
use warnings;

use Net::Telnet;

my $port = 8000;
my $hostname = 'localhost';

my $telnet = Net::Telnet->new(
                        Port      => $port,
                        Host      => $hostname,
                        Dump_log  => 'dump.log',
                        Input_log => 'input.log',
                    );
print "opened\n";

{
    my ($prematch, $match) = $telnet->waitfor('/not likely to show up/');
}

print "after wait\n";

Running the script we notice that after printing "opened" it waits
quite a lot of time and it never prints "after wait".

This happend because waitfor was waiting for a string that never 
showed up. Hence it gave up waiting after the built-in timeout
period. Once it reached the timeout it called the default errmode()
function which is the "die" function. So the script never reached
the second print() and did not have a chance to print anything.


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