How to feed an array of items into Add-LocalGroupMember

PowerShell Help
1

Hello,
I have this code, I can’t figure out how to get the array into the group. I know the top works , if I print out the array before the invoke-command part, it prints out the names I entered. But it is giving an error:

What Computer do you want to add users to local admin group on?: server3
What users do you want to add?: tom
What users do you want to add?: dick
What users do you want to add?: harry
What users do you want to add?: 
Cannot validate argument on parameter 'Member'. The argument is null or empty. Provide an argument that is not null or empty, and then try the command again.
    + CategoryInfo          : InvalidData: (:) [Add-LocalGroupMember], ParameterBindingValidationException
    + FullyQualifiedErrorId : ParameterArgumentValidationError,Microsoft.PowerShell.Commands.AddLocalGroupMemberCommand
    + PSComputerName        : server3

Here is the script:

$Computer = Read-Host -Prompt "What Computer do you want to add users to local admin group on?"
$Userarray = @()
do {
$input = (Read-Host -Prompt "What users do you want to add?")
if($input -ne '') {$Userarray += $input}
	}
until ($input -eq '')

Invoke-Command -ComputerName $Computer -ScriptBlock{
   Add-LocalGroupMember -Group "Administrators" -Member $Userarray
}

Thanks!

2

Here is 1 of my attempts that fails: I have local user accounts called tom, dick, and harry

$Computer = Read-Host -Prompt "What Computer do you want to add users to local admin group on?"
$Userarray = @()
do {
$input = (Read-Host -Prompt "What users do you want to add?")
if($input -ne '') {$Userarray += $input}
	}
until ($input -eq '')

Invoke-Command -ComputerName $Computer -ScriptBlock{
	Foreach ($user in $userarray) {
   Add-LocalGroupMember -Group Administrators -Member $User
}
}
3

You are trying to use a variable inside a script block you defined outside of it. Your issue is about scope.

You may read the following help topics completely including the examples to learn how to deal with scopes.

4

This seems like it should work, but it doesnt do anything and I get no error:

$Computer = Read-Host -Prompt "What Computer do you want to add users to local admin group on?"
$Userarray = @()
do {
$input = (Read-Host -Prompt "What users do you want to add?")
if($input -ne '') {$Userarray += $input}
	}
until ($input -eq '')

Invoke-Command -ComputerName $Computer -ScriptBlock{
	Foreach ($Using:user in $userarray) {
   Add-LocalGroupMember -Group Administrators -Member $User
   
}
}

Ive tried changing the $User variable but still not working. Is $User referenced the same way inside the Invoke command after the $Using:User?

5

$User is not the variable you define OUTSIDE of the scriptblock. :wink:

6

Still no luck.

Here is my code:

$Computer = Read-Host -Prompt "What Computer do you want to add users to local admin group on?"
$Userarray = @()
do {
$input = (Read-Host -Prompt "What users do you want to add?")
if($input -ne '') {$Userarray += $input}
	}
until ($input -eq '')
write-host "before scriptblock"
$Computer
$input

Invoke-Command -ComputerName $Computer -ScriptBlock{
	Foreach ($Using:user in $userarray) {
   Add-LocalGroupMember -Group Administrators -Member $input
    }
   Get-LocalGroupMember Administrators
    hostname
    Write-Host "Inside ScriptBlock"
   $computer
   $input
   $user
    }
    Write-Host "Outside ScriptBlock"
    $computer
   $input
   $user

Output:

What Computer do you want to add users to local admin group on?: server3
What users do you want to add?: tom
What users do you want to add?: harry
What users do you want to add?:
before scriptblock
server3
tom
harry

Inside ScriptBlock
Outside ScriptBlock
ObjectClass Name PrincipalSource PSComputerName

Group BASEMENT\Domain Admins ActiveDirectory server3
User BASEMENT\Guest ActiveDirectory server3
User BASEMENT\SERVER2$ ActiveDirectory server3
User SERVER3\Administrator Local server3
server3
server3

:thinking:

7

$USERARRAY is the variable you define outside the script block and use inside of it. :man_shrugging:t4: :roll_eyes:

$Computer = Read-Host -Prompt "What Computer do you want to add users to local admin group on?"
$Userarray = @()
do {
    $User = Read-Host -Prompt "What users do you want to add?"
    if ($User -ne '') { $Userarray += $User }
}
until ($User -eq '')

Invoke-Command -ComputerName $Computer -ScriptBlock {
    Add-LocalGroupMember -Group Administrators -Member $USING:userarray
}

And BTW: it usually is a bad idea to accept free text input for such a use case. A better option would be to offer a limitted choice the user can choose from.

8

oh so you do not need the foreach then, it just feeds the entire array in.

Thanks!

9

I agree, params with validate set would be ideal.