如何丢弃PowerShell ActiveDirectory cmdlet的错误？

Question

I am writing a PowerShell script (in a PowerShell 5.1 environnement) and I need to list all users from groups set in a folder's permissions. But some groups are not relevant so when I try to Get-ADGroupMember on it, I've got an expected error.

To discard this error, I tried the following :

Get-ADGroupMember Fake_Group -Server ad.example.com 2>&1 $null
Get-ADGroupMember Fake_Group -Server ad.example.com 2>&1 | Out-Null

But in both cases, the result is the same : error is displayed.

get-aduser : Cannot find an object with identity: 'Fake_Group' under 'DC=example.com'.
At line:1 char:1
+ Get-ADGroupMember Fake_Group -Server ad.example.com 2>&1 | ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ObjectNotFound: (Fake_Group:ADGroup) [Get-ADGroupMember], ADIdentityNotFoundException
    + FullyQualifiedErrorId : ActiveDirectoryCmdlet:Microsoft.ActiveDirectory.Management.ADIdentityNotFoundException,Microsoft.ActiveDirectory.Management.Commands.GetADGroupMember

So my question is : why is this error still displayed ?

And then, how could I discard this error or is there a better way to list users from groups set in a folder's permissions than just try to Get-ADGroupMember on the whole result of Get-Acl even on no relevant object ?

Answer 1

Because Out-Null does nothing in this regard, you would need to use try/catch statements and might even need to add -ErrorAction Stop as not all errors in AD commands are terminating errors:

Try{
    Get-ADGroupMember $GROUPNAME -Server $SEVRER -ErrorAction Stop
    #The group is found, do whatever you want here
}Catch{
    Write-Host "Some error occured"
}