Creating backup program (or problem with exec())

Hello all. I am writing a small backup program and am having problems. For some reason, no matter what I try, the exec() won't work. If I remove the variable and put in the actual text, it works fine. Any tips? <? $backup_date = date("mdY"); $backup_date = "redhot" . $backup_date; $backup_path = "/home/httpd/html/sweeps/"; $backup_to = $backup_path . "stats/backups/"; exec("tar --exclude=stats -cf " . $backup_to . $backup_date . ".tar $backup_path"); //exec("gzip /backup.tar"); //exec("mv /backup.tar.gz /public_html/backup.tar.gz"); ?> Thanks CDitty