@advancecoder said:
How do you execute Ruby Plugin API commands in headless mode (e.g. not opening the GUI for Google Sketchup Pro)?
You Don't.
I went 'round and 'round with another guy over at GoogleGroups that thought he could somehow use the engine behind Sketchup (which is Google Intellectual Property,) to write a better GUI and/or integrate it with a debugger.
Anyhow, read the thread if your interested:
http://groups.google.com/group/sketchupruby/browse_frm/thread/8d93e9408891fa59#