Usage: gdal_contour [--help] [--help-general]
[-b <band>] [-a <attribute_name>] [-amin <attribute_name>] [-amax <attribute_name>]
[-3d] [-inodata] [-snodata <n>] [-f <formatname>] [-i <interval>]
[-dsco <NAME>=<VALUE>]... [-lco <NAME>=<VALUE>]...
[-off <offset>] [-fl <level> <level>...] [-e <exp_base>]
[-nln <outlayername>] [-q] [-p]
<src_filename> <dst_filename>