Most people are familiar with the concept of a dead man's switch that, for example, activates the emergency brake should a London Underground train driver become incapacitated. There are many different technologies across multiple machines from the trains mentioned above right through to chainsaws. Unsurprisingly, laptop computers haven't been on the list until now. Software engineer and sysadmin, Michael Altfield, has created a cheap "kill cord" that can trigger a laptop to self-destruct if stolen by a snatch and grab thief. What's more, you can make your own for just $20 (£15) but there's an important caveat: this is for Linux laptops, not those running macOS or Windows.