Read certain lines and split the file.

readLines.py

#!/usr/bin/env python3
# Read lines.

def readLines(filePath, howManyLines=500) :
  lines = list()
  with open(filePath) as theFile :
    number = 0
    while True :
      for i in range(0, howManyLines) :
        line = theFile.readline()
        if not line :
            return
        lines.append(line)
      with open('.'.join([filePath, str(number)]), 'w') as splitedFile :
        splitedFile.write(''.join(lines))
      lines.clear()        
      number += 1

if __name__ == '__main__' :
    from sys import argv
    if len(argv) > 2 :
        readLines(argv[1], int(argv[2]))
    elif len(argv) > 1 :
        readLines(argv[1])
    else :
        print("""\
Please add arguments:
readLines.py file [lines]
file -- the file to split.
lines -- how many line in the splited file.
                """)