title: Send keystroke to Dockerfile, Ubuntu
body: <p>I'm creating Dockerfile script and it has a command line that executes a program and requires user input <strong>1</strong> from keyboard as selected option to go to further steps.</p>
  
  <p><a href="http://www.semicomplete.com/projects/xdotool/" rel="nofollow noreferrer"><strong>Xdotool</strong></a>, <a href="https://stackoverflow.com/questions/6264596/simulating-enter-keypress-in-bash-script"><strong>man yes</strong></a> or <a href="https://stackoverflow.com/questions/6264596/simulating-enter-keypress-in-bash-script"><strong>expect</strong></a> cannot help in this situation.</p>
  
  <p>Update source-code:</p>
  
  <p>First off, download and extract RevoMath library, navigate to RevoMath folder then execute the install script.</p>
  
  <pre>
  <code>
  ...
  RUN wget -q https://mran.microsoft.com/install/mro/3.2.4/RevoMath-3.2.4.tar.gz
  RUN tar -xzf RevoMath-3.2.4.tar.gz
  RUN cd RevoMath/
  RUN ./RevoMath.sh
  ...
  </code>
  </pre>
  
  <p>Install script has some select options as follow:</p>
  
  <pre><code>
  echo "1. Install MKL"
  echo "2. Uninstall MKL"
  echo "3. Exit utility"
  </code></pre>
  
  <p>We need to enter <strong>1</strong> from keyboard to install. How can we do it via Docker command?</p>
  
  <p>Any help would be appreciated!</p>