Here is what I think you should do.

In testlib.pl, write:

$| = 1;
sub test{
$var = "Lord only knows if this will work...";
}
1;
[download]

In your main program, write.

require 'testlib.pl';
$| = 1;
print "Content-type: text/html\n\n";
test();
print "$var";

exit;
[download]