Find out whether a file is a symlink in Powershell

Question

Edit: Changed the question title since the answer explicitly only handles Symlinks.

I am having a Powershell script which is walking a directory tree and sometimes I have auxiliary files hardlinked there which should not be processed. Is there an easy way of finding out whether a file (i. e. System.IO.FileInfo) is a hard link or not?

If not, would it be easier with symlinks?

Answer 1

Try this:

function Test-ReparsePoint([string]$path) {
  $file = Get-Item $path -Force -ea 0
  return [bool]($file.Attributes -band [IO.FileAttributes]::ReparsePoint)
}

It is a pretty minimal impl but should do the trick. Note that this doesn't distinguish between a hard link and a symlink. Underneath, they both just take advantage of NTFS reparse points IIRC.

Answer 2

My results on Vista, using Keith Hill's powershell script to test symlinks and hardlinks:

c:\markus\other>mklink symlink.doc \temp\2006rsltns.doc
symbolic link created for symlink.doc <<===>> \temp\2006rsltns.doc

c:\markus\other>fsutil hardlink create HARDLINK.doc  \temp\2006rsltns.doc
Hardlink created for c:\markus\other\HARDLINK.doc <<===>> c:\temp\2006rsltns.doc

c:\markus\other>dir
 Volume in drive C has no label.
 Volume Serial Number is C8BC-2EBD

 Directory of c:\markus\other

02/12/2010  05:21 PM    <DIR>          .
02/12/2010  05:21 PM    <DIR>          ..
01/10/2006  06:12 PM            25,088 HARDLINK.doc
02/12/2010  05:21 PM    <SYMLINK>      symlink.doc [\temp\2006rsltns.doc]
               2 File(s)         25,088 bytes
               2 Dir(s)   6,805,803,008 bytes free

c:\markus\other>powershell \script\IsSymLink.ps1 HARDLINK.doc
False

c:\\markus\other>powershell \script\IsSymLink.ps1 symlink.doc
True

It shows that symlinks are reparse points, and have the ReparsePoint FileAttribute bit set, while hardlinks do not.