Tuesday, January 25, 2011

Powershell unable to "see" dnscmd.exe

Hi Folks,

Am at a complete loss with this one. Recently a number of my powershell scripts have started failing as they are unable to find the command dnscmd.exe.

What has me at a loss is that the executable exists and works and I can run it just fine in the command prompt. I have tried the following in powershell to run the command:

  • dnscmd
  • & dnscmd
  • & dnscmd.exe
  • & c:\windows\system32\dnscmd.exe

All return "The term dnscmd is not recognized as the name of a cmdlet, function,script file or operable program...."

Can anyone enlighten me as to why powershell is completely unable to see the command, where the normal command prompt/windows explorer etc.. can? Using powershell 2.

  • What do you get when you execute:

    Get-Command dnscmd.exe -CommandType Application

    Ben Short : Get-Command : The term 'dnscmd.exe' is not recognized as the name of a cmdlet, function, script file, or operable progr am. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.
    Ben Short : Just a link to a screenshot - http://dl.dropbox.com/u/8408796/dnscmd.JPG Confirmed that c:\windows\system32\ is in the powershell path.
    From Shay Levy
  • This sounds like the work of the File System Redirector to me. Are you running on a 64bit OS?

    For example, when you make a call to C:\Windows\system32\dnscmd.exe on a 64bit OS using PowerShell (x86), this will be redirected to C:\Windows\SysWow64\dnscmd.exe. The redirection occurs at the point the folder is accessed so even though you are explicitly providing the path to the executable, you'll still be diverted. This can be disabled on the current thread via calls to native Windows APIs or can be avoided through the use of certain variables and aliases.

    More information here: http://msdn.microsoft.com/en-us/library/aa384187%28VS.85%29.aspx

    From fletcher
  • Its the File System Redirect, but you can bypass

    Instead of

    C:\windows\system32
    

    (which the redirector will grab) use

    C:\windows\sysnative\dnscmd.exe
    
    Ben Short : oddly the Windows 7 & Windows Server 2008 machines I am testing this on do not recognise the SysNative alias. Any thoughts on why this may occur? :)
    Ben Short : Scratch that - found out it was because I was running 64 bit Powershell, and not 32, which meant the Wow64 layer was not kicking in.
    From Taylor

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