sgitopnm --version (return code: 0)
sgitopnm: Using libpbm from Netpbm Version: Netpbm 10.0
sgitopnm: BSD defined
sgitopnm: RGB_ENV='RGBDEF'
sgitopnm: RGBENV= 'RGBDEF' (env vbl is unset)
sgitopnm -h (return code: 1)
usage: sgitopnm [-verbose] [-channel n] [sgifile]