A good C alternative for Boost.Program_options?

Question

Any good alternative written in C to replace Boost.Program_options? Given it's able to parse:

1. Short options like -h
2. Long options like --help --input-file
3. Parse repeated keys/options
4. Accepts key-value pairs: --mysql=/usr/lib
5. Parsing environmental variables and XML/INI files is optional.

Answer 1

If you are okay with the GPL license, you want GNU getopt.