Comparing two text files in python

Question

I need to compare two files and redirect the different lines to third file. I know using diff command i can get the difference . But, is there any way of doing it in python ? An

Answer 1

import sys
if len(sys.argv) !=3 :
  print "usage:" + sys.argv[0] + "   bla bla"
  exit
elif len(sys.argv) == 3:
  file1 = set((x for x in open(sys.argv[1])))
  file2 = set((x for x in open(sys.argv[2])))
  file3 = file2.difference(file1)
  file4 = file1.difference(file2)
  str1="file1-contains but  file2 not \n"
  str2="file2-contains but  file1 not\n"
  FILE = open('file3','w')
  FILE.writelines(str2)
  FILE.writelines(file3)
  FILE.writelines(str1)
  FILE.writelines(file4)