NTFS junction point

An NTFS junction point is a symbolic link to a directory that acts as an alias of that directory. This feature of the NTFS file system offers benefits over a Windows shell shortcut (.lnk) file, such as allowing access to files within the directory via Windows Explorer, the Command Prompt, etc.

Unlike NTFS symbolic links Junction points can only link to a local volume; junction points from a local volume to a remote share are unsupported.

Junction points are a type of NTFS reparse point. They were introduced with NTFS 3.0, the default file system for Windows 2000. The Windows 2000 and Windows 2003 Resource Kits include a program called linkd, to create junction points; Mark Russinovich of Winternals released a tool called junction which provided more complete functionality. Windows XP includes "fsutil";Masatoshi Kimura released a filter driver for the soft/symbolic link functionality existing in Windows XP's NTFS version, to be accessible to the end user. Windows Vista, Windows Server 2008, and later operating systems include an mklink command-line utility for creating junction points.

By setting a junction point that points to a directory containing a particular version of a piece of software, it may be possible to add another version of the software and redirect the junction point to point to the version desired.

The contents of a junction use almost no disk space (they simply point to the original files in the original directory). If you need to have multiple points of entry to a large directory, junction points will serve that purpose well. Junction points should not be confused with a copy of something as they simply point to the original. If directories need to be modified separately a junction cannot be used as it does not provide a distinct copy of the directory or files within.

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