GRUB2?

[Tom H]

>> I have forgotten whether the previous version of Ubuntu had an inittab
>> but the current one, 9.10, does not. You can nonetheless modify the
>> init levels at which init scripts are run (or not) and pass an init
>> level as a kernel parameter in grub or through "init X".

> Used to be able to, the latest ubuntu has gone almost totally upstart.
> You try to poke around in places like /etc/rc2.d and find they don't exist
> any more. That eventually led me to the gdm script in the new upstart
> directory (who's name I have already forgotten), and reading that
> script led me to the text parameter on the kernel boot line.

You still can.

The upstart directory of 9.10 is /etc/init (whereas it was
/etc/event.d in 9.04 as it is in Fedora).

To make an upstart job start at runlevels X and Y, you have to edit
the "start" line:
"start on runlevel [XY]"