Get-Unique returns incorrect results

Question

In this PowerShell command to find the owners of files in a folder,

Get-ChildItem $dir -Recurse | foreach {Get-Acl $_.fullname | select owner} | Get-Unique -AsString

Get-Unique returns every result that is different from the one before it instead of checking the whole list. For example:

   domain\user1
   domain\user2
   domain\user1
   domain\user3
   domain\user1

It should return only one of each.

Answer 1

From Get-Help Get-Unique

The Get-Unique cmdlet compares each item in a sorted list to the next item, eliminates duplicates, and returns only one instance of each item. The list must be sorted for the cmdlet to work properly.

To get the result you want, pipe your list through Sort-Object prior to using Get-Unique

$list | sort | Get-Unique

This behavior is the same as the uniq command in Unix.