Where are the session managers logs?

Question

Unity 3D refuses to start here, always falling back to Unity 2D. I installed both Gnome and XFCE 4 and neither starts, but instead leave me with the mouse cursor and the wallpaper. I want to know what is happening. Where are the session manager logs? Where can I see what processes failed to start? Where can I read what they printed to stdout and stderr before they crashed or failed to start properly?

Answer 1

The file you should take a look at is ~/.xsession-errors in your home directory (note, that this collects output from all the graphical programs you start, so not everything you can see there has to be related to your problem).

If there are issues with the greeter/LightDM, then you can go through the logs in /var/log/lightdm (I assume you are using Ubuntu 11.10).