How to Use Hard Links

Hard links create a second directory entry for a single file, whereas symbolic links create a new file that references an existing file. This subtle difference yields significantly different behavior.

You can create hard links by adding the /H parameter to the mklink command. For example, the following command creates a hard link from Link.txt to Target.txt.

As with symbolic links, any changes made to the hard link are made automatically to the target (including attribute changes) and vice versa because the file itself is stored only once on the volume. However, hard links have several key differences:

• Hard links must refer to files on the same volume, while symbolic links can refer to files or folders on different volumes or shared folders.
• Hard links can refer only to files, while symbolic links can refer to either files or folders. n Windows maintains hard links, so the link and the target remain accessible even if you move one of them to a different folder.
• Hard links survive deleting the target file. A target file is deleted only if the target file and all hard links are deleted.
• If you delete a symbolic link target and then create a new file with the same name as the target, the symbolic link will open the new target. Hard links will continue to reference the original target file, even if you replace the target.
• Hard links do not show up as symbolic links in dir command-line output, and Windows Explorer does not show a shortcut symbol for them. Hard links are indistinguishable from the original file.
• Changes made to file permissions on a hard link apply to the target file and vice versa. With symbolic links, you can configure separate permissions on the symbolic link, but the permissions are ignored.

Windows XP supports hard links by using the fsutil hardlink command. Windows Vista and Windows 7 hard links are compatible with Windows XP hard links, and the fsutil hardlink command continues to function in Windows Vista and Windows 7.