ppmtosixel --version (return code: 0)
ppmtosixel: Using libpbm from Netpbm Version: Netpbm 10.0
ppmtosixel: BSD defined
ppmtosixel: RGB_ENV='RGBDEF'
ppmtosixel: RGBENV= 'RGBDEF' (env vbl is unset)
ppmtosixel -h (return code: 1)
usage: ppmtosixel [-raw] [-margin] [ppmfile]