====== Hardlink ======

Also the article for:
  * filename

A hardlink associates a //filename// with a [[dict:terms:file | file]]. That name is an entry in a directory listing. Of course a file can have more hardlinks to it (usually the number of hardlinks to a file is limited), but all hardlinks to a file must reside on the same [[dict:terms:filesystem | filesystem]] as the file itself!

What you usually call a file is just a name for that file, and thus, a hardlink.

The difference between a [[dict:terms:symlink | symbolic link]] and a hard link is that there is no easy way to differentiate between a 'real' file and a hard link, let's take a look at the example:

* create an empty file

<code>$ touch a</code>

* create a hard link 'b' and sym link 'c' to empty file

<code>$ ln a b
$ ln -s a c</code>

as you can see file(1) can't differentiate between a real file 'a' and a hard link 'b', but it can tell 'c' is a sym link

<code>$ file *
a: empty
b: empty
c: symbolic link to `a'</code>

''ls -i'' prints out the inode numbers of files, if two files have the same inode number AND are on the same file system it means they are **hardlinked**.

<code>$ ls -i *
5262 a  5262 b  5263 c</code>


hard links don't consume additional space on the filesystem, the space is freed when the last hard link pointing to it is deleted.

===== See also =====
  * [[dict:terms:file | file]]
  * [[dict:terms:filesystem | filesystem]]
  * [[dict:terms:symlink | symlink]]