Just how many forums have you posted this question to, anyway? I know of at least 3 or 4. The fact of the matter is, to do what you want is a gross violation of system security. You can set up the user's login to do a chroot when they first login to the system, but to allow something like a perl script the ability to do a chroot is just plain dangerous! Maybe if you described what your REAL problem is, we could make some suggestions on how to accomplish your real goals.