Quick question, can't find the answer via Google - I can change things like screensaver timeout / DPMS power-off timeouts etc. using xset.

Where is the file in which these can be specified as permanent variables? Otherwise I find myself re-entering the commands whenever X is restarted.

I was directed towards /etc/X11/xinit/xinitrc, but this just seems to call the /etc/X11/Xsession script, and I didn't want to amend this without double-checking...

I'm sure it's really obvious when you know the answer!

Well like most things in Ubuntu you usually have to use there GUI apps to get it done right. I would try System->Preference->Screensaver to set the screen saver timeout. Inside there is a button to launch power management or you can use System->Preferences->Power Management. I think these two apps should give you what you want.

Hope this works for you

Sorry - forgot to mention in the original post - I'm using Fluxbox. I was a bit rushed!

I can open the Gnome screensaver preferences with gnome-screensaver-preferences and disable that, but the screensaver & monitor power-off were still happening, and it turned out that these are all X variables that can all be displayed with xset q.

I would have thought there will be a global settings file somewhere, otherwise I'll be reduced to having a startup script along the lines of this:

#!/bin/bash
xset s 1200 1200

And that just seems silly.