Chroot
From Gentoo Linux Wiki
A chroot on *nix operating systems is an operation which changes the root directory. It affects only the current process and its children. "chroot" itself can refer to the chroot(2) system call or the chroot(8) wrapper program.
A program that is re-rooted to another directory cannot name files outside that directory. This provides a convenient way to sandbox an untrusted, untested or otherwise dangerous program. It is also a simple kind of jail mechanism.
