Command to get usage % per CPU/core?

Question

Is there a command I can use from the Terminal on OS X to get the usage percentage per CPU/core in numerical format on my dual-core iMac?

I'm going to need to grab this every 5/10 seconds so I'm looking for something "low-cost" - that isn't going to hit the CPU too hard. Maybe something like top, but which shows both CPU/cores, that I can parse and then display in GeekTool;

Core 1: 11%
Core 2: 7%

Answer 1

Top shows individual cores, you only have to press '1'. I think there's also an option to change the refresh rate.

Answer 2

There is a wonderful extension to top, called HTop, which shows real-time graphs per CPU in the top-left of the display, as well as many other controls and great customisability:

There is a tutorial on how to get a HTop port built for OS X:

http://www.geektechnica.com/2009/07/how-to-install-htop-on-osx/

http://github.com/AndyA/htop-osx/tree/master

UPDATE:

htop from macports installs and works perfectly.