I am still much the padawan-learner Monk, but I'm going to offer what I have in hopes it may help.

I've never used ForkManager before, but it looks to me like you're getting that error because if $login ne "SUCCESSFUL!", then you never get to $pm->finish; You could change this if you reverse your test...

Try this:

if $login eq "SUCCESSFUL!" {
   my $stdout = getOSType();
   print "$stdout\n";
}
[download]

and let me know what happens. :)