title: TCL - How to print on the screen th messages that where printed during execution of exec command?
body: <p>Say I have want to execute a script or and executable file by printing runtime the output of execution.</p>
  
  <p>When I do:</p>
  
  <pre><code>set log [exec ./executable_file]
  puts $log
  </code></pre>
  
  <p>Then it waits a long time and then prints everything at once. But I want runtime printing. How can I do this?</p>