title: How to change the default working directory in python
body: <p>I have a quick question about the default working directly on python. 
  I am currently using the python 2.7. In this case the default working directly is the <code>C:/Python27</code>. 
  I want to change this permanently to another directory. 
  Even if we write down following on shell, the default working directory will go back to the original <code>C:/Python27</code> automatically. </p>
  
  <pre><code>import os
  
  os.chdir('a path')
  </code></pre>
  
  <p>Does any one know how to set up default directory permanently to "the path" which keeps the directory after the closing the shell? 
  This is a different question from how to change working directory just by the function temporarily.<br>
  Thank you so much for your help!!</p>