title: Upgrade python packages from requirements.txt using pip command
body: <p>How do I upgrade all my python packages from requirements.txt file using pip command?</p>
  
  <p>tried with below command</p>
  
  <pre><code>$ pip install --upgrade -r requirements.txt
  </code></pre>
  
  <p>Since, the python packages are suffixed with the version number (<code>Django==1.5.1</code>) they don't seem to upgrade. Is there any better approach than manually editing requirements.txt file?</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>As Andy mentioned in his answer packages are pinned to a specific version, hence it is not possible to upgrade packages through pip command.</p>
  
  <p>But, we can achieve this with <code>pip-tools</code> using the following command.</p>
  
  <pre><code>$ pip-review --auto
  </code></pre>
  
  <p>this will automatically upgrade all packages from requirements.txt (make sure to install <code>pip-tools</code> using pip install command).</p>