In this operating system, files can contain data, shell scripts, and programs. File names are also used to represent abstract objects such as sockets or device drivers. Pointers within the i-node structure designate the real disk address of the data blocks associated with the file. The connection of i-numbers and file names is called a link. File names exist only in directories.
Directories are a unique type of file that give hierarchical structure to the file system.
Directories contain directory entries. Each directory entry contains a file name and an i-number. The file system links the file and directory data to the structure used by storage and retrieval mechanisms. The Design of the UNIX Operating System . The Design and Implementation of the 4.3 BSD UNIX Operating System .