macptopbm --version (return code: 0)
macptopbm: Using libpbm from Netpbm Version: Netpbm 10.0
macptopbm: BSD defined
macptopbm: RGB_ENV='RGBDEF'
macptopbm: RGBENV= 'RGBDEF' (env vbl is unset)
macptopbm -h (return code: 1)
usage: macptopbm [-extraskip N] [macpfile]