title: Reading a file until a match found with python
body: <p>I have been trying this code to loop through randomly until a match found in the lookin.txt file and stop when a match is found with no success as my Python knowledge not that brilliant. Code is working only once but i need it to run continously until it finds a match. I appreciate if someone can direct me in the right direction.</p>
  
  <pre><code>        #! /usr/bin/env python
  import random
  randrange = random.SystemRandom().randrange
  z = randrange( 1, 1000)
  
  target_f = open("lookin.txt", 'rb')
  read_f = target_f.read()
  if z in read_f:
      file = open('found.txt', 'ab')
      file.write(z)
      print "Found ",z
  else:
      print "Not found ",z
  </code></pre>
  
  <p>Lookin.txt:</p>
  
  <pre><code>453
  7
  8
  56
  78
  332
  </code></pre>