title: How to pipe stdout while keeping it on screen ? (and not to a output file)
body: <p>I would like to pipe standard output of a program while keeping it on screen.</p>
  
  <p>With a simple example (<code>echo</code> use here is just for illustration purpose) :</p>
  
  <p><code>$ echo 'ee' | foo</code><br>
  <code>ee</code>  &lt;- the output I would like to see</p>
  
  <p>I know tee could copy stdout to file but that's not what I want.<br>
  <code>$ echo 'ee' | tee output.txt | foo</code></p>
  
  <p>I tried<br>
  <code>$ echo 'ee' | tee /dev/stdout | foo</code> but it does not work since tee output to <code>/dev/stdout</code> is piped to <code>foo</code></p>