Thanks for your response.
Your solution sounds complex compared to nsclient. So I think you answered my question. There is no comparable (ie "out of the box") solution like nsclient for retrieving resource info from unix hosts. That's surprising considering Nagios was created on unix (I think).
When I have time I'll dig deeper and try to understand your suggestion. But that's the problem. I don't have time. That's why I was hoping for something like that just works like nsclient. But I don't mean to sound ungrateful. Actually I am very thankful for what Nagios developers have done for the rest of us.