pgmnoise --version (return code: 0)
pgmnoise: Using libpbm from Netpbm Version: Netpbm 10.0
pgmnoise: BSD defined
pgmnoise: RGB_ENV='RGBDEF'
pgmnoise: RGBENV= 'RGBDEF' (env vbl is unset)
pgmnoise -h (return code: 1)
usage: pgmnoise width height
width and height are picture dimensions in pixels