Scary stuff! But, what I can't work out is how he's embedded the RETURN into the hidden code? Usually when I paste a command into my terminal, it sits there w

Scary stuff! But, what I can't work out is how he's embedded the RETURN into the hidden code? Usually when I paste a command into my terminal, it sits there waiting for me to hit RETURN, before it executes. And, if I copy his 'nasty code' from the terminal after it executes and paste it in again, it sits there waiting for me to hit RETURN. So how does he make it simulate hitting the RETURN key, the first time?