This wasn't a FB interview - this was a phone screen before you got to the interview. Every linux sysadmin under the sun can answer 90% of those questions from "muscle memory." The purpose of this phone screen was to ensure that the incredibly expensive time of the interviewers was only used to meet potential candidates.

There are certain trivia or data that the entire community of linux sysadmins know, just by having worked with the operating system - and, if you miss more than about 20% of those questions - one can say with pretty much certainty that you are not a linux sysadmin.

I thought the questions were roughly the ones I would give to a technical recruiter to screen.

(PS: ls -lart - muscle memory, I type it 100+ times a day)