# create new directory here
    if (($pid = fork()) == 0) {
       # remove directory here
    }
    if (!defined($pid)) {
       # log fork() failure here
       # remove directory here
    }
[download]

You need to reverse your tests, and check for undef'ness of $pid first. For enlightenment as to why, ponder on   print undef == 0 ? "true!\n" : "false\n";