title: Access permission to execute a script
body: <p>I understand that three types of permissions to a file (read, write, execute) can be set independently, hence there are eight possibilities per file per user (superuser, group, normal user). Based on this fact, I had believed that a superuser can set a certain script file (in my case, a Ruby file) to be executable but not read/writable to a normal user. But in the context of <a href="https://stackoverflow.com/questions/16002558">this question</a>, Wayne Conrad and Linuxios noted me that a script cannot be run by a user who does not have read permission to that file.</p>
  
  <ol>
  <li><p>Why is this the case? If a user needs read permission in order to execute it, then why is it possible to set the three permission types independently? Particularly, what does it mean to set a script file permission to executable but not readable?</p></li>
  <li><p>Is there some way (hackish, it may be) to make a script file runnable but not readable from a certain user?</p></li>
  </ol>