Compare two list and find names that are in list one and not list two using powershell

Question

Just wondering if you can help me out.. I am trying to compare two list(txt file) and find strings that are in list A and not in List B and output it to another txt file.. anybody know how to do it using powershell ?

Here is what I have so far:

Compare-Object -ReferenceObject $FolderLists -DifferenceObject $AdUserName -passThru

I would like to find all strings that are in $FolderLists and not $AdUserName and possibly output it to another variable. The issue I am having is that it outputs strings that are not in both lists.

Solution

I assume $FolderList and $AdUserName are arrays of strings? You don't really need Compare-Object to compare arrays. It's as simple as this:

$FolderList | ?{$AdUserName -notcontains $_}

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Compare-Object is for comparing the specified properties of collections of objects with common properties. You could do this with Compare-Object if you really want, like this:

Compare-Object $FolderList $AdUserName | ?{$_.SideIndicator -eq '<='} | Select-Object -ExpandProperty InputObject

But as you can see, it's overkill for this task.

To output the result to another variable, simply assign it:

$AnotherVariable = $FolderList | ?{$AdUserName -notcontains $_}