Powershell - User creation script avoid duplicate username - powershell

Question

I would like to do an Active Directory search using PowerShell to discover if the username I want to create is already in use,. If it is already in use I want the script to add the following number at the and of the user name.
Import-Module ActiveDirectory
$family= Mclaren
$first= Tony
#This part of the script will use the first 5 letters of $family and the first 2 letters of $first and join them together to give the $username of 7 letters
$username = $family.Substring(0, [math]::Min(5, $family.Length)) + $first.Substring(0, [math]::Min(2, $first.Length))
The user name will look like "mclarto" base on that (username
take the 5 first letters of the family name plus 2 charof the firstname)
a seach is done in AD.
If there is no result, "mclarto" will be taken as $username without
any number at the end.
If the search find other users with the same username, the
username should take the following number, in this case it would be
"mclarto1".
If "mclarto1" already exist then "mclarto2" should be use and so on.

Answer 1

I think this will get you close, it uses the ActiveDirectory module.
Import-Module ActiveDirectory
$family = "Mclaren*"
# Get users matching the search criteria
$MatchingUsers = Get-ADUser -Filter 'UserPrincipalName -like $family'
if ($MatchingUsers)
{
# Get an array of usernames by splitting on the # symbol
$MatchingUsers = $MatchingUsers | Select -expandProperty UserPrincipalName | %{($_ -split "#")[0]}
# loop around each user extracting just the numeric part
$userNumbers = #()
$MatchingUsers | % {
if ($_ -match '\d+')
{
$userNumbers += $matches[0]
}
}
# Find the maximum number
$maxUserNumber = ($userNumbers | Measure-Object -max).Maximum
# Store the result adding one along the way (probably worth double checking it doesn't exist)
$suggestedUserName = $family$($maxUserNumber+1)
}
else
{
# no matches so just use the name
$suggestedUserName = $family
}
# Display the results
Write-Host $suggestedUserName