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MKLINK [[/D] | [/H] | [/J]] Link Target

/D Creates a directory symbolic link. Default is a file symbolic link.
/H Creates a hard link instead of a symbolic link.
/J Creates a Directory Junction.
Link specifies the new symbolic link name.
Target specifies the path (relative or absolute) that the new link refers to.

Isn't a directory junction the exact same thing as a directory symbolic link?

What's the difference between mklink /D f1 f2 and mklink /J f1 f2 ?

Also, I was under the impression that a directory is like some kind of file so what's the difference between a directory symbolic link and a file symbolic link?

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Related: superuser.com/q/347930/24500 –  surfasb Dec 29 '11 at 13:05
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1 Answer

up vote 75 down vote accepted

A junction is definitely not the same thing as a directory symbolic link, although they behave similarly. The main difference is that, if you are looking at a remote server, junctions are processed at the server and directory symbolic links are processed at the client. Also see Matthew's comment on the fact that this means symbolic links on the local filesystem can point to remote filesystems.

Suppose that on a machine named Alice you were to put a junction point c:\myjp and a directory symbolic link c:\mysymlink, both pointing to c:\targetfolder. While you're using Alice you won't notice much difference between them. But if you're using another machine named Bob, then

\\Alice\c$\myjp -> \\Alice\c$\targetfolder

but

\\Alice\c$\mysymlink -> \\Bob\c$\targetfolder.

(Caveat: by default, the system doesn't follow symlinks on remote volumes, so in most cases the second example will actually result in either "File Not Found" or "The symbolic link cannot be followed because its type is disabled.")

The difference between a directory symbolic link and a file symbolic link is simply that one represents a directory and one represents a file. Since the target of the link doesn't need to exist when the link is created, the file system needs to know whether to tell applications that it is a directory or not.

It should also be noted that creating a symbolic link requires special privilege (by default, only available to elevated processes) whereas creating a junction only requires access to the file system.

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Just to be clear: there may well be other subtler functional differences between directory junctions and directory symbolic links. The remote vs. local thing is just the most obvious from a user (as opposed to a developer) perspective. –  Harry Johnston Oct 5 '11 at 4:02
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@MatthewSteeples do you mean that if I create a symbolic link C:\testlink (which points to C:\test on my computer) and someone remote access my computer and clicks on C:\testlink, it would resolve to the C:\test on HIS computer, Whereas if I create a directory junction C:\testlink (which points to C:\test on my computer), and someone remote access my computer and clicks on C:\testlink) it would lead him to the C:\test on my computer? Or did I get it the wrong way round? –  Pacerier Oct 5 '11 at 8:19
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@Pacerier in this context yes, but symbolic links allow you to have a folder on your computer that points to a network share (because they're resolved client side). Eg C:\MyNetworkShare could actually point to \\Alice\Share –  Matthew Steeples Oct 6 '11 at 14:57
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@MatthewSteeples but couldn't we create a directory junction C:\MyNetworkShare which points to \\Alice\Share as well? –  Pacerier Oct 7 '11 at 10:44
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@Pacerier, no, junction points have to be local. –  Harry Johnston Oct 8 '11 at 0:05
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