gemtopbm --version (return code: 0)
gemtopbm: Using libpbm from Netpbm Version: Netpbm 10.0
gemtopbm: BSD defined
gemtopbm: RGB_ENV='RGBDEF'
gemtopbm: RGBENV= 'RGBDEF' (env vbl is unset)
gemtopbm -h (return code: 1)
usage: gemtopbm [-debug] [gem IMG file]