title: os.system doesn't work in Python
body: <p>I'm working on windows vista, but I'm running python from DOS command. I have this simple python program. (It's actually one py file named test.py)</p>
  
  <pre><code>import os
  os.system('cd ..')
  </code></pre>
  
  <p>When I execute "python test.py" from a Dos command, it doesn't work.
  For example, if the prompt Dos Command before execution was this:</p>
  
  <pre><code>C:\Directory&gt;
  </code></pre>
  
  <p>After execution, must be this:</p>
  
  <pre><code>C:\&gt;
  </code></pre>
  
  <p>Help Plz.</p>