Definition and Usage
This function works like the system call by the same name: it makes the named directory the new root directory for all further pathnames that begin with a / by your process and all its children. For security reasons, this function, which is identical to the system chroot( ) function, is restricted to the superuser and cannot be undone.
If FILENAME is omitted, then it does a chroot to $_
0 on failure
1 on success