Acyclic Graph Directories

In this kind of directory structure the shared directories or files can exist in the file system in two or more places at once. A tree structure excludes the sharing of files or directories. An acyclic graph namely a graph with no cycles allows directories to share subdirectories and files. The acyclic graph is a usual generalization of the tree structured directory scheme. It is more flexible in comparison of a simple tree, but it is as well more complex.

A directory or shared file isn't the same as two copies of the same file or directory. With two copies if one copy is changed subsequently the changes will not be reflected in the other copy. With a shared file, the alterations made by one person are immediately visible to the other. Sharing is a significant concept for subdirectories. A fresh file created by one person will automatically come into view in all the shared subdirectories.

Implementation:       

Directories and Shared files can be executed by creating a new directory entry called link which points to another subdirectory or file. When a reference to a file is made then the directory is searched. If the directory entry is marked like a link after that the name of the real file is included in the link information. The link is resolve by using the path name to locate the real file.

Another method is to copy (duplicate) all information about shared files in both the sharing directories.

                                                                                  Acyclic Graph directory structure