"cd\"
"cd .." is the Unix/Linux way.
>The black death gave white populations (who survived) immunity to the vectors that HIV/AIDS use.
That's wrong in numerous ways. But the short one is that the Black Death was caused by a bacterial infection. Bacteria have no need to target receptors on cells to get inside and start replicating.
They're not sure which plague caused it.
https://www.sciencedaily.com/releases/2005/03/050325234239.htm