The quit method does not exit the script for me. Simple test:

#!/usr/bin/perl

use strict;
use warnings;

use Net::FTP;

my $ftp = Net::FTP->new ('ftp.perl.org');
$ftp->login ('anonymous');
print $ftp->pwd ();
$ftp->quit;
print "And now an extra line.\n";
[download]

which results in the expected output:

That's with version 2.77 of Net::FTP.

I ran your testcase in and out of the debugger and you're correct- I have the same result.

In my case there must be something else going on, because I get this:

  DB<6> l
281==>b    closedir DIR;
282:       $ftph->quit();
283
284:       open STDERR, ">&OLD_STDERR";
285
286:       $result->{status} = 0;
287:       return $result;
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and when I press n 2 times...

  DB<6> n
genericFTP::ftpFiles(/var/www/cgi-bin/orderform/genericFTP.pm:282):
282:       $ftph->quit();
DB<6> n
Debugged program terminated.  Use q to quit or R to restart,
  use o inhibit_exit to avoid stopping after program termination,
  h q, h R or h o to get additional info.
[download]

Turned out that $ftph had gone out of scope and was undef. But instead of telling me that, Perl decided to go to

CGI::DESTROY

for some reason, which quickly lead to an exit without reporting anything. and use strict and warning didn't throw anything.

Once I fixed the scope everything was fine. What an odd way to (NOT) report the object was undef!? If Perl had simply said object $ftph not defined, it would have been a 1 second fix.

Thanks for your tip I voted you ++

My guess is you're being hit with SIGPIPE. Try catching the signal.