While it leads to slightly more chance of traceability, I've seen one line "curl | sh" which install a tool which transmit everything you type, or just your pas

While it leads to slightly more chance of traceability, I've seen one line "curl | sh" which install a tool which transmit everything you type, or just your password (when you next type it) off to a remote server, so once you've left a terminal unattended you are in trouble anyway. This is one place when windows can be much better, as users can't catch ctrl+alt+del, so you can always press that before logging in.