Rename Microsoft 365 groups for naming policy

# Review required modules and connection steps before running.
# Connect to Microsoft Graph or Exchange Online as needed for this script.

Write-Host "Checking that prerequisite PowerShell modules are loaded..."
Try { $OrgName = (Get-OrganizationConfig).Name }
   Catch  {
      Write-Host "Your PowerShell session is not connected to Exchange Online."
      Write-Host "Please connect to Exchange Online using an administrative account and retry."
      Break }
 
$AzureADCheck = Get-Module -Name AzureADPreview
If ($AzureADCheck -eq $Null) {
     Write-Host "Your PowerShell session is not connected to Azure Active Directory (Preview)."
     Write-Host "Please connect to Azure Active Directory using an administrative account and retry."; Break }
 
# Get organization naming policy setting
$Policy = Get-AzureADDirectorySetting | ? {$_.DisplayName -eq "Group.Unified"}
$NamingPolicy = $Policy["PrefixSuffixNamingRequirement"]
 
If (!($NamingPolicy))
   { Write-Host "No naming policy defined..."
     EXIT }
   Else
   { Write-Host "Groups naming policy is" $NamingPolicy }
 
# Check if a prefix or a suffix is used to name groups
$Suffix = $False; $Prefix = $False
If ($NamingPolicy.Substring(0,11) -eq "[GroupName]") { # Suffix is used, not a prefix
    $Suffix = $NamingPolicy.Split("]")[1]
    $GroupsNameMatch = "*" + $Suffix + "*" }
Else { #Assume a prefix
    $Prefix = $NamingPolicy.SubString(0,($NamingPolicy).IndexOf("[GroupName"))
    $GroupsNameMatch = "*" + $Prefix + "*" }
# Find Microsoft 365 Groups that don't match the naming policy
$Groups = (Get-UnifiedGroup | ? {$_.DisplayName -NotLike $GroupsNameMatch})
 
If ($Groups.Count -gt 0)
   { $Prompt = "You have " + $Groups.Count + " groups to update. Proceed? [Y/N]"
     $Answer = Read-host -Prompt $Prompt
     If ($Answer.ToUpper() -ne "Y")
        {
         Write-Host "Exiting..."
         EXIT }
     }
# Update Groups
Write-Host "Updating Groups with new display names..."
 
ForEach ($G in $Groups) {
   If ($Prefix -ne $False) { # Update with a new prefix
        $NewDisplayName = $Prefix + $G.DisplayName
        Write-Host $G.DisplayName "updated to" $NewDisplayName
        Set-UnifiedGroup -Identity $G.DistinguishedName -DisplayName $NewDisplayName
   } #End If
   Elseif ($Suffix -ne $False) {
        $NewDisplayName = $G.DisplayName + $Suffix
        Write-Host $G.DisplayName "updated to" $NewDisplayName
        Set-UnifiedGroup -Identity $G.DistinguishedName -DisplayName $NewDisplayName
   } #End Elseif
} #End ForEach