I have about 50 000 points (latitude and longitude), and I would like to find out in which country each of the points is located. It does not need to be super precise, though.
(Or actually I only need to classify them to larger geographical areas (North America, South America, Europe, Africa, Middle East, Ex-USSR, Asia, Oceania), but I assume classifying the points to countries and then the countries to larger geographical area is the way to do it.)
How should I proceed?
Preferably the tool to do this should be free, run on Linux, and be a command-line tool, or e.g. Python or R program (I can write the program if I find some starting points or hints) or some library that I could use. I have no experience in GIS software, and I would prefer a programmable or a command line solution.