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