How to find the number of occurrance of each word in a file using python [duplicate]

Possible Duplicate:

Read words from .txt, and count for each words

Python script to find word frequencies of a given document

There is one file having some data in it. I would like to get each and every word without repetition and want to get number of occurance 开发者_JAVA百科of that word. How do I write a python program for this?