Link

A link is a named connection between a directory and an object. A user or a program can tell the system where to find an object by specifying the name of a link to the object. A link can be used as a path name or as part of a path name.

For users of directory-based file systems, it is convenient to think of an object, such as a file, as something that has a name that identifies it to the system. In fact, it is the directory path to the object that identifies it. You can sometimes access an object by giving just the object's name. You can do this because the system is designed to assume the directory part of the path under certain conditions. The idea of a link takes advantage of the reality that it is the directory path that identifies the object. The name is given to the link rather than the object.

After you get used to the idea that the link has the name rather than the object, you begin to see possibilities that were hidden before. There can be multiple links to the same object. For example, two users can share a file by having a link from each user's home directory to the file (see Home directory). Certain types of links can cross file systems, and can exist without an object existing.

There are two types of links: Hard link and Symbolic link. When using path names in programs, you have a choice of using a hard link or a symbolic link. Each type of link has advantages and disadvantages. The conditions under which one type of link has an advantage over the other type is as follows: