pbmreduce --version (return code: 0)
pbmreduce: Using libpbm from Netpbm Version: Netpbm 10.0
pbmreduce: BSD defined
pbmreduce: RGB_ENV='RGBDEF'
pbmreduce: RGBENV= 'RGBDEF' (env vbl is unset)
pbmreduce -h (return code: 1)
usage: pbmreduce [-floyd|-fs | -threshold] [-value <val>] N [pbmfile]