pgmenhance --version (return code: 0)
pgmenhance: Using libpbm from Netpbm Version: Netpbm 10.0
pgmenhance: BSD defined
pgmenhance: RGB_ENV='RGBDEF'
pgmenhance: RGBENV= 'RGBDEF' (env vbl is unset)
pgmenhance -h (return code: 1)
usage: pgmenhance [-N] [pgmfile] ( 1 <= N <= 9, default = 9 )