обзор иерархии файловой системы (File system hierarchy overview)
NODE TYPES
Unix file systems support different types of file nodes,
including regular files, directories, symlinks, character and
block device nodes, sockets and FIFOs.
It is strongly recommended that /dev/ is the only location below
which device nodes shall be placed. Similarly, /run/ shall be the
only location to place sockets and FIFOs. Regular files,
directories and symlinks may be used in all directories.