The NTFS file system supports three types of file links: hard links, junctions, and symbolic links. This article is an overview of hard links and junctions. For information about symbolic links, seeCreate symbolic links.

Hard links

Ahard link is the file-system representation of a file by which more than one path references a single file in the same volume. To create a hard link, use theCreateHardLinkA function.

Any changes made to a hard-linked file are instantly visible to applications that access it through the links that reference it. The attributes on the file are reflected in every hard link to that file, and changes to that file's attributes propagate to all the hard links. However, the directory entry size and attribute information of the file arevisibly updated only at the link through which the change was made. For example, if you clear the read-only attribute flag on a particular hard link so you can delete that hard link, and there are multiple hard links to the file, the other hard links display that the read-only attribute is still set, which isn't true. To change the file back to the read-only state, you must set the read-only flag on the file from one of its remaining hard links.

For example, in a system whereC: andD: are local drives andZ: is a network drive mapped to\\fred\share, the following references are permitted as a hard link:

• C:\dira\ethel.txt linked toC:\dirb\dirc\lucy.txt
• D:\dir1\tinker.txt linked toD:\dir2\dirx\bell.txt
• C:\diry\bob.bak linked toC:\dir2\mina.txt

This is because all the links are files on the same volume. Hard links can't reference directories, only files, and they can't reference files on different volumes.

The following references aren't permitted:

• C:\dira linked toC:\dirb
• C:\dira\ethel.txt linked toD:\dirb\lucy.txt
• C:\dira\ethel.txt linked toZ:\dirb\lucy.txt

To delete a hard link, use theDeleteFileA function. You can delete hard links in any order regardless of the order in which they're created.

Junctions

Ajunction (also called asoft link) differs from a hard link in that the storage objects it references are separate directories. A junction can also link directories located on different local volumes on the same computer. Otherwise, junctions operate identically to hard links. Junctions are implemented throughreparse points.

Assuming the same conditions in the Hard Links section, the following references are permitted as junctions:

• C:\dira linked toC:\dirb\dirc
• C:\dirx linked toD:\diry

The following references aren't permitted because they reference mapped network volumes, or they directly reference files:

• C:\dira\one.txt linked toC:\dirb\two.txt
• C:\dir1 linked toZ:\dir2

Related content

• Create symbolic links
• Reparse points