ppmshift --version (return code: 0)
ppmshift: Using libpbm from Netpbm Version: Netpbm 10.0
ppmshift: BSD defined
ppmshift: RGB_ENV='RGBDEF'
ppmshift: RGBENV= 'RGBDEF' (env vbl is unset)
ppmshift -h (return code: 1)
usage: ppmshift shift [ppmfile]
shift: maximum number of pixels to shift a line by