There's a program for Linux that does the same, but using your phone (or other Bluetooth device) called blueproximity. It had a slight tendency for false positives, though - sometimes it locked the screen even with the device less than a meter away.
I used blueproximity successfully with my Linux laptop. I bought the smallest bluetooth headset I could find ($25), removed all extraneous parts, and carried it on my person (not my bag). It was so small that I didn't notice it. Effectively like two-factor authentication for unlocking my laptop.
It's unwise to use your phone for this purpose, because a phone and laptop might both be swiped if you're not holding on to both. This has happened to folks at cafes or on mass transit in the Bay Area.
I've tried to use blueproximity at some point (mostly for convenience because I sometimes forget to lock my screen), but the range of BT devices is too large for comfort. I could be anywhere in my flat or in the medium-sized open plan office at work and the phone in my pocket would still be in range.
Have you tried configuring it? It has a slider that you can adjust to set a minimum power level, so that if the device is too far away it locks anyway, even if it can still detect it.
I had a laptop once that for some reason wouldn't use the battery even on a full charge. So, naturally, as soon as the power cord was pulled out, the laptop crashed.
Would make for a pretty good DMS; being deceiving with a battery attached and the OS reporting a full charge.
I wonder if there's a way to modify the mainboard (knife a lead or something) to be incapable of using the battery while still charging and the OS still being able to get reporting data.
> I wonder if there's a way to modify the mainboard (knife a lead or something) to be incapable of using the battery while still charging and the OS still being able to get reporting data.
Why go the hardware route? The AC adapter state is reported to the operating system; for instance, KDE on my laptop plays a sound when a blackout cuts the power to the AC adapter. It should be simple to have something else monitor the power state and tell logind to lock all screens on AC power loss, or even force a shutdown if you're paranoid.
Not that it would help much; there are devices which can keep the AC power on while a computer is unplugged and transported, even for desktops (which have no internal battery). Nothing prevents these devices from also being used on laptops.
