Also, from the article:

"You need to be very carful when writing to any /dev/sd* or /dev/mmblk* devices, because you can wipe your main drive (this happens to almost everyone at least once)"

Yeah, been there. I remember back in my datacenter days, meant to do a personal background operation on my laptop before I went out to swap hard drives. Menat to dd of=/dev/sda2 and accidentally dd of=/dev/sda. I did NOT have a backup and suddenly realized I was overwriting my MBR.

Luckily I recovered everything! I think I used an "MBR-guessing" tool.

It's amazing how fast and efficient command line tools can be at running accidental havoc...