[ubuntu] How to switch on webcam-led on Lenovo W520?

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http://ubuntuforums.org – Hi folks, my Lenovo W520 is running Ubuntu 12.04. Just next to the integrated webcam, there is a led-flashlight, which works under Windows. I wonder how to switch it on/off in Ubuntu (I do not mean the "ThinkLight" (to enlight the keyboard), which can be toggled via Fn+PageUp) Does anyone know how to do it? (Hardware)