Loop device

In Unix-like operating systems, a loop device, vnd (vnode disk), or lofi (loop file interface) is a pseudo-device that makes a file accessible as a block device. In Unix-like operating systems, a loop device, vnd (vnode disk), or lofi (loop file interface) is a pseudo-device that makes a file accessible as a block device. Before use, a loop device must be connected to an existing file in the filesystem. The association provides the user with an API that allows the file to be used in place of a block special file (cf. device file system). Thus, if the file contains an entire file system, the file may then be mounted as if it were a disk device. Files of this kind are often used for CD ISO images and floppy disc images. Mounting a file containing a filesystem via such a loop mount makes the files within that filesystem accessible. They appear in the mount point directory.