splitter.py

#!/usr/bin/env python

from os.path import splitext
import sys

name, suff = splitext(sys.argv[1])
fi = 0
fh = open('%s%s.%s' (name, fi, suff), 'w')
for i,row in enumerate(open(sys.argv[1])):
    fh.write(row)
    if i > 0 and i % 500 == 0:
        fh.close()
        fi += 1
        fh = open('%s%s.%s' (name, fi, suff), 'w')