SymLinks on Windows! (Power users only!!)

[jason]

I never knew you could do this, but it is pretty cool!

If you are a *nix power user, one of the things that has probably really frustrated you when you're in Windows is that Windows doesn't have symbolic links. The closest thing, Windows shortcuts, only work in Explorer: if you double click on a shortcut it will open its target, but you can't, for example, reference a shortcut in code and expect to get the contents of the target file when you do an fopen() on the shortcut path.

Well, if you're running NTFS 5.0 or better (Win 2k or better), there is a feature of the filesystem called a reparse point (also known as a junction point) that works very much like a unix symlink. They aren't wel documented by MS, but there are a handful of third-party utilities to work with them.

The easiest way I've found to create reparse points is with a free program from SysInternals (now part of MS) called junction. You can download junction from http://www.microsoft.com/technet/sys.../Junction.mspx.

Open the zip file and drop junction.exe to some folder in your path, then open a command prompt and type

junction c:\link-name c:\path\to\target

Note: the syntax is backwards from the unix ln -s syntax, which would be ln -s /path /to/target link-name

Junction points can point to files or directories and they can span volumes. For example:

junction c:\d-drive d:\

will create a junction point at c:\d-drive that will point to the root directory of your d: drive.

Junctions appear just like file folders in Windows Explorer. They show up in command line "dir" output as <JUNCTION>, however.

WARNING: It appears that if you delete a junction point from the explorer you may delete the target as well (including all files in the directory if the target is a directory)! Therefore you should use a junction point management tool (like Sysinternals' junction) to remove junction points.

Here's a good reference on the topic: http://shell-shocked.org/article.php?id=284

Does anyone else know about this? I wish I had known about it sooner.

[Pawel Kowalski]

Thanks for posting that. Really shortcuts have worked just well in all the things I've been wanting to as I never had issues with a windows program recognizing a ink file. If I ever do I'll be sure to check out this solution. Thanks.

[Gwaihir]

NTFS junctions are more like hard links than they are like sym links. There's another thingy called "shell link" that's more like a symlink. (Is that the shortcut explorer uses too? Anyway; these aren't explorer only, but if a program isn't programmed to respect them, it will ignore them.)

I use the freeware GUI tool Winbolic Link (www.pearlmagik.com) to manage both. Mainly I have a few junctions to make various development folders accessible from under the localhost Apache webroot, for some quick testing. (Apache ignores the shell links.)

You're quite right about the power users only not. One has to be carefull with junctions; they are made at a very low level, in the NTFS filesystem. Your OS and applications are totally oblivious to them, so do watch out that you for example don't get your backup program in an endless loop. If you create a junction that points back to higher up in the same filesystem tree, it would get stuck in that loop, thinking it's still following the tree ever further down.

[Vin DSL]

Cool!

So, you're saying (jason) that I could, for instance, FTP into my site using Internet Exploder, open a folder window, symlink using a junction point, and have my account at JagPC come up as a local drive, instead of remote folders?

[jason]

I think it only works for NTFS->NTFS junctions, so I doubt you'd be able to point the jusction at an FTP "share."

I run FreeSSHd on a couple of Windows boxes so that I can make tunnels to them and whanot. One drawback of the software though is that the SFTP server it includes limits you to a single directory tree (by default its $HOME--the logged in user's home directory). I have a system on which I'd like to access files on both C: and D: and I haven't been able to do that, but with a junction point on c:\ that points to d:\ I now can. (I haven't tried Gwaihir's tool on it yet, but I plan to.)

--Jason

[Vin DSL]

I see...

Okay, Mr. Power User... what's the bene to 'us', then?

[Vin DSL]

Windows Vista

Windows Vista supports a new NTFS symbolic link capability that replaces junction points in Windows 2000 and Windows XP. Microsoft has implemented its symbolic links to function just like UNIX links. They are designed to aid in migration and application compatibility with UNIX operating systems. Microsoft uses them internally to maintain backward naming convention compatibility for user's profile's among other things.

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