It locks the screen by executing "xscreensaver-command -lock"

So this is a "kill cord" in the meaning of a jetski, power boat, or treadmill where pulling out the kill cord triggers a fast but nondestructive stop.

It can do whatever you want it to do. The examples in the article were:

• whenever any USB drive is removed, trigger xscreensaver to lock the screen:

> ACTION=="remove", SUBSYSTEM=="usb", RUN+="DISPLAY=:0 xscreensaver-command -lock"

• whenever a specific USB drive is removed, shut down the computer:

> ACTION=="remove", SUBSYSTEM=="usb", ENV{ID_MODEL}=="Micromax_A74", RUN+="shutdown -h now"

Nitpick, it can do whatever you want it to do that’s possible in software. You’ll be disappointed if you want to have it drill a hole in your hard drive ;)

Just build a USB-powered hard-drive drill, duh.

It appears to simply be a USB plug that works with a simple software driver to automatically log out if the USB is unplugged. The scenario is a snatch-and-grab of the laptop while the user is logged in to a highly-secure, high-value online account.

Not something most users likely need but I can imagine some TLAs being interested in something like this, as it looks pretty inexpensive to implement.

It simply uses udev to identify when the USB device is removed, then executes a linux command of your choosing. In the examples provided, he demonstrates a simple 'lockscreen' and 'shutdown' command.

It's clever, I'll admit, but the name leaves more to be desired with a name like 'buskill'

The article shows two different configurations, one that simply triggers the screensaver with a lock screen, the other to fully shut the machine down. Recovery from both of those is fairly straightforward.

> [...] rule that will trigger xscreensaver to lock the screen every time any USB drive is removed