Whenever a user locks his machine, and whenever a user unlocks a machine, Windows emits an event. PowerShell can subscribe to these events and do things, for example use the text-to-speech engine to emit greetings.
But there are a number of useful actions as well. Maybe you want to clean up when you lock your machine, close all Windows Explorer windows, start a backup, or do something else. Here is the sample code:
function Start-LogMessage { $null = Register-ObjectEvent -InputObject ([Microsoft.Win32.SystemEvents]) -SourceIdentifier SessSwitch -EventName "SessionSwitch" -Action { Add-Type -AssemblyName System.Speech $synthesizer = New-Object -TypeName System.Speech.Synthesis.SpeechSynthesizer switch($event.SourceEventArgs.Reason) { 'SessionLock' { $synthesizer.Speak("Have a good one, $env:username!") } 'SessionUnlock' { $synthesizer.Speak("Heya, nice to see you $env:username again!") } } } } function Stop-LogMessage { $events = Get-EventSubscriber -SourceIdentifier SessSwitch $jobs = $events | Select-Object -ExpandProperty Action $events | Unregister-Event $jobs | Remove-Job }