Spacerats little techwiki

• Remove offending key from known_hosts file with one swift move

$ sed -i 18d .ssh/known_hosts

• Whats my WAN IP?

$ dig +short myip.opendns.com @resolver1.opendns.com

• Math on the cli

$ echo $((2+2))
4
$ echo $((4/2))
2
$echo $((1*2))
2