title: TENSORFLOW on machine with no GPU, can`t manage to run it on CPU only
body: <p>I am learning about Tensorflow (would like to integrate it with my chatbot) and would like to run the example found here:</p>
  
  <p><a href="https://www.tensorflow.org/tutorials/recurrent" rel="nofollow noreferrer">https://www.tensorflow.org/tutorials/recurrent</a> </p>
  
  <p>I downloaded the suggested repository, installed tensorflow (now the cpu-only version, but tried also the --gpu) but got stuck with this:</p>
  
  <pre><code> python ptb_word_lm.py --data_path=simple-examples/data/ --model=small --rnn_mode=basic
  2017-09-21 17:38:09.856638: W tensorflow/core/platform/cpu_feature_guard.cc:45] The TensorFlow library wasn't compiled to use SSE4.1 instructions, but these are available on your machine and could speed up CPU computations.
  2017-09-21 17:38:09.856685: W tensorflow/core/platform/cpu_feature_guard.cc:45] The TensorFlow library wasn't compiled to use SSE4.2 instructions, but these are available on your machine and could speed up CPU computations.
  Traceback (most recent call last):
    File "ptb_word_lm.py", line 532, in &lt;module&gt;
      tf.app.run()
    File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/platform/app.py", line 48, in run
      _sys.exit(main(_sys.argv[:1] + flags_passthrough))
    File "ptb_word_lm.py", line 459, in main
      % (len(gpus), FLAGS.num_gpus))
  ValueError: Your machine has only 0 gpus which is less than the requested --num_gpus=1.
  </code></pre>
  
  <p>My system has no CUDA GPU (well, it has, but CUDA 1.3, not the >=3 that tensorflow requires), how to get the example code to run in cpu-only mode instead of just quitting?</p>