Forum OpenACS Q&A: Re: (Error: can't read "address": no such variable) after Install OpenACS with NaviServer from Scratch
FYI, if you run nsd from the terminal, it's normal for it to quit with ctrl-c.
Since you've already installed on ubuntu using the install-ns.sh script, you should be able to control starting, stopping the server with:
sudo status oacs-5-9
sudo start oacs-5-9
sudo stop oacs-5-9
There should be no need to do something else.