CentralNotice UnionFS From Wikipedia, the free encyclopedia Jump to: navigation , search Unionfs Developer Open Source Community Full name Unification File System Features File system permissions POSIX Transparent compression No Transparent encryption No (provided at the block device level) Other Supported operating systems Linux , FreeBSD and NetBSD Unionfs is a filesystem service for Linux , FreeBSD and NetBSD which implements a union mount for other file systems . It allows files and directories of separate file systems, known as branches, to be transparently overlaid, forming a single coherent file system. Contents of directories which have the same path within the merged branches will be seen together in a single merged directory, within the new, virtual filesystem. When mounting branches, the priority of one branch over the other i...