title: How to fill user input for interactive command for "RUN" command?
body: <p>I'm just trying ubuntu:19.04 on docker image, I wish to install tcl in the image so I have:</p>
  
  <pre><code>RUN apt update &amp;&amp; apt install tcl
  </code></pre>
  
  <p>Then it will give some interactive commands:</p>
  
  <pre><code>Please select the geographic area in which you live. Subsequent configuration questions will narrow this down by presenting a list of cities, representing
  the time zones in which they are located.
  
  1. Africa   3. Antarctica  5. Arctic  7. Atlantic  9. Indian    11. SystemV  13. Etc
  2. America  4. Australia   6. Asia    8. Europe    10. Pacific  12. US
  </code></pre>
  
  <p>I've 2 problems here:</p>
  
  <p>(1) If I write this command for "RUN" in Docker file, after inputing a number here, "docker build ." seems to be hang by it.</p>
  
  <p>(2) I wish I don't have to manually input a choice, do I have any way to feed a choice in "RUN" so that its automated?</p>