In UNIX-like operating systems, each process has its own idea of what the root directory is. For most processes this is the same as the system's actual root directory, but it can be changed by calling the chroot system call. This is typically done to create a secluded environment to run software that requires legacy libraries and sometimes to simplify software installation and debugging. Chroot is not meant to be used for enhanced security as the processes inside can break out. FreeBSD offers a stronger jail() system call that enables operating-system-level virtualization and also serves security purposes to restrict which files a process may access to just a subset of the file system hierarchy.