I sent off the previous message too soon. Carlos Robinson:
If the computer is not going to be used, and it is not a server, it makes much more sense to switch it off. Less electricity used, less air conditioning needed, less wear on hard disks and ventilators, less noise, less danger that cleaning staff unplug something or just move it (very dangerous for HDs)... and more security (you can not crack an off computer), and no fsck needed.
All are true. Moreover, one reason I've seen for leaving it on certainly doesn't apply: there is (or used to be) a myth in 'doze-using circles that booting a Linux machine is a lengthy process; with this machine at least, it's fast. Well, I'd read that the wear 'n' tear on bits of computer caused by leaving them on tended to be outweighed by that of heating them up and cooling them down. It's an issue that no doubt is discussed ad nauseam on various web pages (with various degrees of knowledge); I'll take a look tomorrow. In the meantime, just for a change, I'll turn off this system when I leave for home ten minutes from now.