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Hard Links
Hard links are the original Unix way of creating links, compared to symbolic links, which are more modern. By default, every file has a single hard link that gives the file its name. When we create a hard link, we create an additional directory entry for a file. Hard links have two important limitations:
1. A hard link cannot reference a file outside its own file system. This means a link cannot reference a file that is not on the same disk partition as the link itself.
2. A hard link may not reference a directory.
A hard link is indistinguishable from the file itself. Unlike a symbolic link, when you list a directory containing a hard link you will see no special indication of the link. When a hard link is deleted, the link is removed but the contents of the file itself continue to exist (that is, its space is not deallocated) until all links to the file are deleted.
It is important to be aware of hard links because you might encounter them from time to time, but modern practice prefers symbolic links, which we will cover next.