Discuss the mount and unmount system calls.

The privileged mount system call is used to join a file system to a directory of another file system; the unmount system call detaches a file system. When you mount another file system on to your directory, you are fundamentally splicing one directory tree onto a branch in another directory tree. The first argument to mount call is the mount point, that is, a directory in the current file naming system. The next argument is the file system to mount to that point.