title: file.write() in python
body: <pre><code>import os
  import sys
  import re
  import string
  
  f=open('./iprange','r')
  s=f.readline()
  f.close()
  pattern='inet addr:'+s
  pattern=pattern.split('x')[0]
  pattern='('+pattern+'...'+')'
  
  os.system('ifconfig -a &gt;&gt; interfaces')
  f=open('./interfaces','r')
  s=f.readline()
  
  while (len(s))!=0:
      i=re.search(pattern,s)
      if i!=None:
          sp=re.split(pattern,s)[1]
          ip=re.split('inet addr:',sp)[1]
          break
      s=f.readline()
  
  f.close()
  os.system('rm ./interfaces')
  f=open('./userip','w')
  f.write(ip)
  f.close()
  
  NameError;name 'ip' is not defined
  </code></pre>
  
  <p>I split <code>pattern</code> by <code>s</code> and store the result in <code>sp</code>, then I find the IP address and store the result in <code>ip</code>. But the error says <code>ip</code> is not defined - what's going on?</p>