Ever since I started managing Macs in a corporate environment, I’ve been annoyed that Apple has failed to offer a sanctioned way of locking the screen via a keyboard command. This is a reasonably common requirement in a lot of corporate deployments. Sure we can use hot corners etc, or we can use one of the sanctioned methods to activate the loginwindow via Fast User Switching, but the former isn’t for everyone, and the latter sucks because it will tear down userspace VPN/802.1x connections.

We have reasonable MCX controls to require a password for the screensaver, but nothing to actually activate it. There are a bunch of private API calls you can use to achieve this, but using private APIs makes me feel dirty.

When I first started poking at Automator again in 10.6, I was pleased to notice that we have a “Start Screen Saver” action. This means that we can save such an Automator workflow as a Service, and then assign a keyboard command to it such that we can activate it from any application.

Unfortunately this action is buggy. If you activate the workflow and wiggle the mouse around, you’ll get an error dialog after unlocking the screen.

Luckily we have another way of achieving the same goal. The System Events AppleScript dictionary contains the same functionality.


tell application "System Events"
start current screen saver
end tell


So you can simply create an Automator “Service” workflow and add a “Run AppleScript” action with the following code snippet.


on run {input, parameters}

return input
end run


Save it, and assign a hot key, and you can finally activate the screensaver from the keyboard.