Update Environment

gistfile1.ps1

function Get-EnvironmentVariableNames([System.EnvironmentVariableTarget] $Scope) {
    switch ($Scope) {
        'User' { Get-Item 'HKCU:\Environment' | Select-Object -ExpandProperty Property }
        'Machine' { Get-Item 'HKLM:\SYSTEM\CurrentControlSet\Control\Session Manager\Environment' | Select-Object -ExpandProperty Property }
        'Process' { Get-ChildItem Env:\ | Select-Object -ExpandProperty Key }
        default { throw "Unsupported environment scope: $Scope" }
    }
}

function Get-EnvironmentVariable([string] $Name, [System.EnvironmentVariableTarget] $Scope) {
    [Environment]::GetEnvironmentVariable($Name, $Scope)
}

Write-Host "Running 'Update-SessionEnvironment' - Updating the environment variables for the session."

  #ordering is important here, $user comes after so we can override $machine
  'Machine', 'User' |
    % {
      $scope = $_
      Get-EnvironmentVariableNames -Scope $scope |
        % {
          Set-Item "Env:$($_)" -Value (Get-EnvironmentVariable -Scope $scope -Name $_)
        }
    }

  #Path gets special treatment b/c it munges the two together
  $paths = 'Machine', 'User' |
    % {
      (Get-EnvironmentVariable -Name 'PATH' -Scope $_) -split ';'
    } |
    Select -Unique
  $Env:PATH = $paths -join ';'