Disable automatic start of the GUI in Ubuntu 9.10 (Karmic Koala)

Apparently Ubuntu changed the startup process significantly in Karmic, since GDM is now not started by a startup script in one of the the /etc/rc[0-9].d directories, but something else. Even the /etc/init.d/gdm filesystem entry was changed: it's now a symlink pointing to /lib/init/upstart-job. The latter is part of the upstart package which has the following description ...

Description: event-based init daemon
Upstart is a replacement for the /sbin/init daemon which handles starting of tasks and services during boot, stopping them during shutdown and supervising them while the system is running.

It seems that this new upstart init daemon uses config files from /etc/dbus-1/*/* and /etc/init. The gdm package puts one config file into both directory trees.

However to stop GDM from loading the GUI, you can just add a "text" string to the kernel parameter list (eg. in /etc/default/grub if you're using Grub).