Add-Path.ps1

Function global:Add-Path()
{
  [Cmdletbinding()]
  param (
    [parameter(Mandatory=$True, ValueFromPipeline=$True, Position=0)]
    [String[]]$AddedFolder
  )

  # Get the current search path from the environment keys in the registry.
  $OldPath=(Get-ItemProperty –Path 'Registry::HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\Environment' –Name PATH).Path

  # See if a new folder has been supplied.
  IF (!$AddedFolder)
  { 
    Return 'No Folder Supplied. $ENV:PATH Unchanged'
  }

  # See if the new folder exists on the file system.
  IF (!(TEST-PATH $AddedFolder))
  { 
    Return 'Folder Does not Exist, Cannot be added to $ENV:PATH'
  }

  # See if the new Folder is already in the path.
  IF ($ENV:PATH | Select-String -SimpleMatch $AddedFolder)
  { 
    Return 'Folder already within $ENV:PATH' 
  }

  # Set the New Path
  $NewPath=$OldPath+';'+$AddedFolder

  Set-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\Environment' -Name PATH –Value $newPath

  # Show our results back to the world
  Return $NewPath
}