I started the server in detached mode (-d), how do I attach back to it so that I can kill the server).
Yu can see the id of the ruby process:
ps aux | grep ruby
username 17731 0.1 1.6 3127008 67996 ?? S 2:00PM 0:01.42 /Users/username/.rvm/rubies/ruby-1.9.2-p180/bin/ruby script/rails s -d
and kill process by id:
kill -9 17731