Change Runlevel

Robert,
the following link may help you:
http://forums.macrumors.com/showthread.php?t=203557
Also, the following book may be useful:
http://www.osxbook.com/

Mihalis.

Hi Robert,
You're right this is easy but there's no bull in Mihalis's answer. OK, no bull from one southerner to another, there ain't no such a thing! Your resumé is System V types and Linux but Mac OS X is based on BSD and Berkeley's version had no run levels. While many BSD derivatives have adopted the multiple-script rc.d architecture, Apple is trying to develop a replacement, launchd.

Thinking about this has caused me to think of what I believe to be missing from launchd. Launchd is a basically simple concept, "event-driven process initialization". What I think is missing is the concept of "service availability" as one of the events to which launchd can respond. That way you could have startup "chains" that determine dependencies.

I apologize for the above diversion but since you asked about something that doesn't exist, there's not a lot one can say beyond that fact. I know it's not what you wanted to hear but that doesn't make it bull and it's impolite of you to suggest that it is, especially when the difficulty ultimately derives from your question. Maybe if you described what you ultimately want to accomplish, someone could find a way to do it.
--
Gary
~~~~
Aphasia:
Loss of speech in social scientists when asked
at parties, "But of what use is your research?"

Hi Robert,
One method is described at MacOSXHints. Unfortunately on Tiger logging in as >console has been reported as being intermittent.
--
Gary
~~~~
Parents often talk about the younger generation as if
they didn't have much of anything to do with it.

How would I go to single user mode after booting normally?

Gary's link shows one method, in a somewhat abnormal context. The essential bit is

sudo shutdown now

which you can do from Terminal.

I have also seen this posted on osxfaq.com. When I tried it (must be a couple of years ago now) I seemed to get messages all over the place so I prefer a simple reboot holding Command-S.