Reads a Netpbm file as input. Copies each image in the input into a separate file, in the same format.
pnmfile is the file specification of the input file, or - to indicate Standard Input. The default is Standard Input.
output_file_pattern tells how to name the output files. It is the file specification of the output file, except that the first occurence of ''pnmsplit__ fails.
The default output file pattern is