pnmmontage --version (return code: 0)
pnmmontage: Using libpbm from Netpbm Version: Netpbm 10.0
pnmmontage: BSD defined
pnmmontage: RGB_ENV='RGBDEF'
pnmmontage: RGBENV= 'RGBDEF' (env vbl is unset)
pnmmontage -h (return code: 1)
usage: pnmmontage [-0|-1|...|-9] [-header=headerfile] [-quality=n]
[-prefix=defprefix] [KEY:]pnmfile ...