title: How can I create a loop between two TTYs?
body: <p>Every Hello has a response. Second TTY will send a hello to the sender TTY and vice versa:</p>
  
  <pre><code>echo 'echo hello &gt; /dev/pts/1' &gt; /dev/pts/0
  </code></pre>
  
  <p>The 1st receiver should send "hello" to the original sender, but it does not. What is wrong?</p>
  
  <p><strong>[Clarification]</strong> I have two shells running. /dev/pts/1 is the initial sender. </p>