A PowerShell cmdlet for setting environment variables for AppPoolIdentity users

Set-AppPoolEnvVariable.ps1

function global:Set-AppPoolEnvVariable {
  param (
    [string]$appPool = $(Read-Host "Application Pool"),
    [string]$varName = $(Read-Host "Variable name"),
    [string]$varValue = $(Read-Host "Variable value")
  )
  $sec  = "System.Security.Principal";
  $acct = New-Object "$sec.NTAccount" -ArgumentList "IIS AppPool\$appPool";
  $sid  = $acct.Translate([System.Type]::GetType("$sec.SecurityIdentifier")).Value;
  
  Set-ItemProperty -Path "Registry::HKEY_USERS\$sid\Environment" -Name $varName -Value $varValue;
}