import sys import os OUTFIL_PREFIX = "out_" def error_exit(message, code=1): sys.stderr.write("Error:\n{}".format(str(message))) sys.exit(code) def err_write(message): sys.stderr.write(message) def make_out_filename(prefix, idx): '''Make a filename with a serial number suffix.''' return prefix + str(idx).zfill(4) def bsplit(in_filename, bytes_per_file): '''Split the input file in_filename into output files of bytes_per_file bytes each. Last file may have less bytes.''' in_fil = open(in_filename, "rb") outfil_idx = 1 out_filename = make_out_filename(OUTFIL_PREFIX, outfil_idx) out_fil = open(out_filename, "wb") byte_count = tot_byte_count = file_count = 0 c = # Loop over the input and split it into multiple files # of bytes_per_file bytes each (except possibly for the # last file, which may have less bytes. while c != '': byte_count += 1 out_fil.write(c) # Bump vars; change to next output file. if byte_count >= bytes_per_file: tot_byte_count += byte_count byte_count = 0 file_count += 1 out_fil.close() outfil_idx += 1 out_filename = make_out_filename(OUTFIL_PREFIX, outfil_idx) out_fil = open(out_filename, "wb") c = # Clean up. in_fil.close() if not out_fil.closed: out_fil.close() if byte_count == 0: os.remove(out_filename) def usage(): err_write( "Usage: [ python ] {} in_filename bytes_per_file\n".format( sys.argv[0])) err_write( "splits in_filename into files with bytes_per_file bytes\n".format( sys.argv[0])) def main(): if len(sys.argv) != 3: usage() sys.exit(1) try: # Do some checks on arguments. in_filename = sys.argv[1] if not os.path.exists(in_filename): error_exit( "Input file '{}' not found.\n".format(in_filename)) if os.path.getsize(in_filename) == 0: error_exit( "Input file '{}' has no data.\n".format(in_filename)) bytes_per_file = int(sys.argv[2]) if bytes_per_file <= 0: error_exit( "bytes_per_file cannot be less than or equal to 0.\n") # If all checks pass, split the file. bsplit(in_filename, bytes_per_file) except ValueError as ve: error_exit(str(ve)) except IOError as ioe: error_exit(str(ioe)) except Exception as e: error_exit(str(e)) if __name__ == '__main__': main()