Steam on Linux users, beware! Your hard drive(s) could be in grave danger.
Per PC Gamer, here's the skinny: last week Github user Keyvin found that, after moving his Steam folder to a new location, it suddenly and inexplicably stopped launching. After a crash, he restarted Steam. It seemed like things were in working order again, but then:
"It re-installed itself and everything looked great. Until I looked and saw that steam had apparently deleted everything owned by my user recursively from the root directory. Including my 3tb external drive I back everything up to that was mounted under /media."
So that's a nightmare scenario. Fortunately, Keyvin had the bulk of his precious, precious data backed up in the cloud. Since then, other users have reported losing their entire Home directories, among other things.
According to ReadWrite, the data doom bug originates from a scripting error, and while it won't take your operating system, it will swipe just about everything else from your penguin-shaped cookie jar.
Valve is looking into the issue, though they claim it's not super widespread at this point. They told GamesBeat:
"So far, we have had only a handful of users report this issue, after they manually moved their Steam install. We have not been able to reproduce the reported issue, but we are adding some additional checks to ensure this is not possible while we continue to investigate. If anyone else has experienced this or has more information, they should E-mail email@example.com."
So yeah, be careful when moving your Steam install, or maybe just hold off on doing it at all until this issue is 100 percent ironed out. Better safe than on your knees screaming at the heavens, cursing the foul technology deities that allowed this to happen.