title: What is Bazel in TensorFlow? When do I need to build again?
body: <p>I'm new to Bazel. I'm not sure how this thing works. On the <a href="https://www.tensorflow.org/versions/v0.6.0/get_started/os_setup.html" rel="noreferrer">TF website</a>, there's this section on "Create the pip package and install".</p>
  
  <pre><code>$ bazel build -c opt //tensorflow/tools/pip_package:build_pip_package
  
  # To build with GPU support: 
  $ bazel build -c opt --config=cuda //tensorflow/tools/pip_package:build_pip_package
  
  $ bazel-bin/tensorflow/tools/pip_package/build_pip_package /tmp/tensorflow_pkg
  
  # The name of the .whl file will depend on your platform. 
  $ pip install /tmp/tensorflow_pkg/tensorflow-0.5.0-cp27-none-linux_x86_64.whl
  </code></pre>
  
  <p>Here's the situation:</p>
  
  <ol>
  <li>There's a new commit on the master branch of TensorFlow and I merge it into my fork.</li>
  <li>I need to rebuild the wheel and do a pip install of the new wheel (correct me if I am wrong).</li>
  <li>I ./configure first, then bazel build, then bazel-bin, then pip install.</li>
  </ol>
  
  <p>Is this the correct way to properly update changes from master? The bazel build step takes a really long time.</p>