pgmtoppm --version (return code: 0)
pgmtoppm: Using libpbm from Netpbm Version: Netpbm 10.0
pgmtoppm: BSD defined
pgmtoppm: RGB_ENV='RGBDEF'
pgmtoppm: RGBENV= 'RGBDEF' (env vbl is unset)
pgmtoppm -h (return code: 1)
usage: pgmtoppm <colorspec> [pgmfile]
<colorspec1>-<colorspec2> [pgmfile]
-map mapfile [pgmfile]