To follow on directly from my previous post I have since dicovered some really useful applictions to this
1. remote shutdown, (sort of)
if you want to shutdown normally via ssh you need to
sudo shutdown -h now
you can combibe the above in one command
ssh pi@ip-of-pi sudo shutdown -h now
you only then need to enter the root password for sudo. (rther than the password to login then another (or the same) for sudo.
replace shutdown -h now with reboot to reboot the pi.