Checking if file is not empty and if it is f.write to it

Ok, so I am basically trying to f.write a specific set of code if nothing in the file exists already. This is the code I'm using:

import sys
import os
from string import *

userType = raw_input("Enter text: ")

bigtable = '''<html>
<head>
<style>
table, th, td {
    border: 1px solid black;
    border-collapse: collapse;
}
th, td {
    padding: 5px;
    text-align: left;    
}
</style>
</head>
  <body>
    <table style="width:50%">
        <tr>
          <th>Server</th>
          <th>Address</th>
          <th>Name</th> 
          <th>Address2</th>
        </tr>'''

if userType == 'file -n' or userType == 'file --nice':

    with open('Pass.html', 'r') as f:

      if str(f) != 0 :
        print('butters')
      else:
        f.write(bigtable)

Can anybody explain why this does not work and if it is possible to scan a file and then write specific information into it?

Found a way to make it work with:

    with open('Pass.html', 'a') as f:

        if os.path.getsize('C:\Python26\Pass.html') != 0 :
            print('butters')
        else:
            f.write(bigtable)

Solution

Once you've opened the file in append mode (as in your edit), use tell() to see if the file was empty (or nonexistent) before.