Acyclic-Graph Structured Directories
The tree structured directory system doesn't allow the same file to exist in multiple directories therefore sharing is major concern in tree structured directory system. We can provide sharing by making the directory an acyclic graph. In this system, two or more directory entry can point to the same file or sub directory. That file or sub directory is shared between the two directory entries.
These kinds of directory graphs can be made using links or aliases. We can have multiple paths for a same file. Links can either be symbolic (logical) or hard link (physical).
If a file gets deleted in acyclic graph structured directory system, then
1. In the case of soft link, the file just gets deleted and we are left with a dangling pointer.
2. In the case of hard link, the actual file will be deleted only if all the references to it gets deleted.