If you deploy Docker containers based on an official imagine, you might want to set a root password for heightened security.

Type “root” with no password, and simply try that several times until the system relents and lets you in. How does one change the root password? It’s simple enough.

SGI Challenge S - how to change the root password (and does anyone have a copy of the irix media?) ...

If you're jailbreaking your iPhone to get tethering up and running, be sure to change the root access password once you do. Besides hacker ransom attempts, it's just good security sense.

There appears to be a critical flaw within macOS High Sierra that allows anyone with physical access to a Mac running the operating system to gain full administrator access, no password required.