How to add users to AD group and delete some specific user files based on first letters username with Powershell

Question

hope someone could help, I'm unfortunatelly not a Powershell expert

This is what I want:

look up users in the AD within specific OUs, based on first letter(s) of username. Validate if they are member of a AD group, and if not; delete some specific profile files of the user AND add the user to that specific group.

Some part of the code I tried:

Import-Module ActiveDirectory

# OUs needed to be searched for users
$OU1 = 'name of first OU'
$OU2 = 'name of 2nd OU'
$OU3 = 'name of 3rd OU'

# AD group where users needs to be added
$Group = 'name of group'

# Ask for 1st letter of username
$usernameletter = Read-Host -Prompt 'First letter(s) username'

# Create an array with corresponding users
$userslist= @()

$users1 = Get-ADUser -Filter "SamAccountName -like '$usernameletter*'" -SearchBase $OU1 | select -ExpandProperty samAccountName
$users2 = Get-ADUser -Filter "SamAccountName -like '$usernameletter*'" -SearchBase $OU2 | select -ExpandProperty samAccountName
$users3 = Get-ADUser -Filter "SamAccountName -like '$usernameletter*'" -SearchBase $OU3 | select -ExpandProperty samAccountName


$userslist += $users1,$users2,$users3


# check membership of group
$members = Get-ADGroupMember -Identity $Group -Recursive | Select -ExpandProperty sAMAccountName


# Delete userpref files of user when user is not member of the -name of group-

foreach ($user in $userslist)
{
If ($members -contains $user)
{
Write-host "$user exists in group, so userpref files won't be deleted"
} 
    Else 
    {

#if users doesn't exist in AD Group - delete userpref files of user
Write-host "$user doesn't exist in group, deleting userpref files of user"

Remove-Item -Path E:\users\$user\pwrmenu\UserPref\{F5BE2CE1-BF67-44E2-B5B3-5E081344A70E}* -Force
}
}



# check if user is part of the group. if not, add it to the group

foreach ($user in $userslist)
{
If ($members -contains $user)
{
Write-host "$user exists in group, so user won't be added to group $group"
} 
    Else 
    {

#if users doesn't exist in AD Group - add them to AD Group
Write-host "$user doesn't exist in group, adding user to group $group"
Add-ADGroupMember $Group -Members $userslist
}
}

#end of script

for some reason the $userslist array is filled, but the foreach loop $user in $userslist doesn't work, $user is not filled in and it get errors like

Remove-Item : Cannot find path 'E:\users\pwrmenu\UserPref' because it does not exist. Add-ADGroupMember : Cannot validate argument on parameter 'Members'. The argument is null, empty, or an element of the argument collection contains a null value.

Hope that someone could help me! thanks!

Edit @Andrew Ryan Davis,

sorry, not very familiar with this website yet

contents of $userslist:

PS C:\Users\serverw> $userslist

WGoossensTest

wgoossenstest2

contents of $members:

PS C:\Users\serverw> $members

username1

username2

username3

etc

Answer 1

Not sure why you wouldn't have anything populated in user. I do see you have quite a bit of duplicated code as well as several chances for optimization. If you keep the users as an object with a samaccountname property, you can speed up your where clause by not invoking a scriptblock.

$userslist | where samaccountname -notin $members

or

$userslist | where $members -notcontains samaccountname

You also check each user against the list of group members twice. Check out the optimized version below.

Import-Module ActiveDirectory

# OUs needed to be searched for users
$OUs = 'name of first OU','name of 2nd OU','name of 3rd OU' 

# AD group where users needs to be added
$Group = 'name of group'

# Ask for 1st letter of username
$usernameletter = Read-Host -Prompt 'First letter(s) username'

# Create an array with corresponding users
$userslist = $ous | foreach {
    Get-ADUser -Filter "SamAccountName -like '$usernameletter*'" -SearchBase $_ | select samaccountname
}

# Get member list of group
$members = Get-ADGroupMember -Identity $Group -Recursive | Select -ExpandProperty sAMAccountName

# Delete userpref files of user when user is not member of the -name of group- and then add to the group
foreach($user in $userslist | where samaccountname -notin $members | select -ExpandProperty sAMAccountName)
{
    Write-host "$user doesn't exist in group, deleting userpref files of user"
    Remove-Item -Path E:\users\$user\pwrmenu\UserPref\{F5BE2CE1-BF67-44E2-B5B3-5E081344A70E}* -WhatIf
    Write-host "$user doesn't exist in group, adding user to group $group"
    Add-ADGroupMember $Group -Members $user -whatif
}

#end of script

This does not provide feedback of users in the group. If you really want to see that then you can split them up and run each separately.

Import-Module ActiveDirectory

# OUs needed to be searched for users
$OUs = 'name of first OU','name of 2nd OU','name of 3rd OU' 

# AD group where users needs to be added
$Group = 'name of group'

# Ask for 1st letter of username
$usernameletter = Read-Host -Prompt 'First letter(s) username'

# Create an array with corresponding users
$userslist = $ous | foreach {
    Get-ADUser -Filter "SamAccountName -like '$usernameletter*'" -SearchBase $_ | select samaccountname
}

# Get member list of group
$members = Get-ADGroupMember -Identity $Group -Recursive | Select -ExpandProperty sAMAccountName

$notmembersof,$membersof = $userslist.where({$_.samaccountname -notin $members},'split')

# Delete userpref files of user when user is not member of the -name of group- and then add to the group
foreach($user in $notmembersof.sAMAccountName)
{
    Write-host "$user doesn't exist in group, deleting userpref files of user"
    Remove-Item -Path E:\users\$user\pwrmenu\UserPref\{F5BE2CE1-BF67-44E2-B5B3-5E081344A70E}* -WhatIf
    Write-host "$user doesn't exist in group, adding user to group $group"
    Add-ADGroupMember $Group -Members $user -whatif
}

foreach($user in $membersof.sAMAccountName)
{
    Write-host "$user exists in group, so userpref files won't be deleted"
    Write-host "$user exists in group, so user won't be added to group $group"
}
#end of script

Another issue you may have already ran into is your Add-ADGroupMember targets the entire $userslist instead of each $user. I added -WhatIf so you can triple check what's going to happen before completing.

Edit

If $userlist may be empty then we should do a check, something like.

if($null -eq $userlist){write-host "userlist is empty";break}

The error in your comment shows that $userlist was empty, try these tests.

$members = 'test'
$userlist = 'test'
$match,$nomatch = $userlist.where({$_ -in $members},'split')

$members = 'test1'
$userlist = 'test'
$match,$nomatch = $userlist.where({$_ -in $members},'split')

Neither will error and in the first $match will be populated and $nomatch will be empty. In the second the opposite will be true. In neither case will it error like the one you saw.