Get unique AD values with powershell

Have you tried group-object?

get-aduser -filter *  | Group-Object -Property Title | Select Name

or

get-aduser -filter * | Sort-Object -Property Title | Get-Unique

or

Get-aduser -filter * | Sort-object title -unique

Instead of -Filter *, you can also use -Resultsetsize $null

None of the above works.

The first gives nothing
The second gives all user with all properties
The third gives a single user

get-aduser -Resultsetsize $null | Group-Object -Property Title | Select Name

On Powershell v2.0 and Windows Server 2003 i got correct results using the below command

Get-User -resultsize unlimited | Group-Object -Property Title | Select Name

You can't use get-aduser without -filter. Further, using Group-Object just to make something unique is oversized. This should work and perform much better:
 Get-ADUser -filter * -Resultsetsize $null | select -Expand Title | Get-Unique
It dismissed the superfluous properties at the earliest, and works on only title (as a string, because of -Expand).

This doesn't work either. I get this error:

PS C:\Windows\system32> get-aduser -filter * -resultsetsize $null | select -Expa
nd Title | Get-Unique
Select-Object : Cannot process argument because the value of argument "obj" is
null. Change the value of argument "obj" to a non-null value.
At line:1 char:51
+ get-aduser -filter * -resultsetsize $null | select <<<<  -Expand Title | Get-
Unique
    + CategoryInfo          : InvalidArgument: (:) [Select-Object], PSArgument
   NullException
    + FullyQualifiedErrorId : ArgumentNull,Microsoft.PowerShell.Commands.Selec
   tObjectCommand

Yep, thats the one, nice. Thanks.

I added "| Sort-Object Title" in the end to sort it alphabetically, just because I could :-)

Thanks again.