Shit I never remember

gistfile1.md

What is the difference between ${var}, "$var", and "${var}" in the Bash shell?

http://stackoverflow.com/questions/18135451/what-is-the-difference-between-var-var-and-var-in-the-bash-shell

tl;dr - curly braces are used to disambiguate, quotes are used to form a "single word".

SSH keys

http://stackoverflow.com/questions/2419566/best-way-to-use-multiple-ssh-private-keys-on-one-client

Ethernet MTU

http://networkengineering.stackexchange.com/questions/5057/what-is-the-actual-size-of-an-ethernet-mtu http://stackoverflow.com/questions/3928766/how-big-is-an-ip-packet-frame-including-headers