What is it?

CDO (https://code.zmaw.de/projects/cdo/wiki) is a command line tool for processing gridded data in different 
formats (NetCDF,GRIB1,GRIB2). It has several hundred operators built in and can handle very large files.

cdo.rb (http://rubygems.org/gems/cdo) is a Ruby module to access the functionality of CDO. It requires a CDO 
installation.

Some simple examples are included in the online documentation: http://rubydoc.info/gems/cdo/frames. More of 
them can be seen in the included unit tests. Watch the code online under 
https://code.zmaw.de/projects/cdo/repository/changes/trunk/cdo/contrib/ruby/test/test_cdo.rb after 
self-registration here: https://code.zmaw.de/account/register.

Hope you'll enjoy it!
ralf