Combine multiple logical operators

Question

Is there a way to combine parameters for multiple logical operators in a where statement?

Basically I have a statement like this:

<command chain> | where {$_.user.tostring() -ne "USER1" -and $_.user.tostring() -ne "USER2" -and $_.user.tostring() -ne "USER3"}

It's actually a fairly long chain, so I'd like to simplify it so that it becomes something like this:

<command chain> | where {$_.user.tostring() -ne {"USER1" -or "USER2" -or "USER3"}}

The above statement doesn't work, so any suggestions please on how to go about this?

Answer 1

You want to use this:

where {$_.user.tostring() -notin ("USER1","USER2","USER3")}

Or this:

where {($_.user.tostring() -ne "USER1") -and ($_.user.tostring() -ne "USER2") -and ($_.user.tostring() -ne "USER3") }

That's really about as simple as you can get. The boolean operators should, in general, only be used to combine comparison operators (or other things you know represent boolean values).

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Your code here:

where {$_.user.tostring() -ne {"USER1" -or "USER2" -or "USER3"}}

This is basically nonsense. It's always going to evaluate to true. {"USER1" -or "USER2" -or "USER3"} is of datatype ScriptBlock.

PS C:\> ({"USER1" -or "USER2" -or "USER3"}).GetType().FullName
System.Management.Automation.ScriptBlock

I believe PowerShell will cast this to a string, but even if it gets cast to a string, it's still not evaluated as a boolean expression:

PS C:> ({"USER1" -or "USER2" -or "USER3"}).ToString()
"USER1" -or "USER2" -or "USER3"

That's going to evaluate to True unless the user is literally '"USER1" -or "USER2" -or "USER3"'

If you changed it so that it was a parenthetic expression instead of a script block:

where {$_.user.tostring() -ne ("USER1" -or "USER2" -or "USER3")}

Then it would always be true. ("USER1" -or "USER2" -or "USER3") is of type Boolean, and will always have the value of true.

PS C:\> ("USER1" -or "USER2" -or "USER3")
True

So you're basically running:

where {$_.user.tostring() -ne $true }

Again, even if PowerShell converts everything to a string like I think it will, it's pretty unlikely you've got a user named "True". So this will always be true.