title: What does "set -t" do in bash?
body: <p>I've tried testing this but it doesn't seem to work the way the manual says it does - from <code>help set</code>:</p>
  
  <blockquote>
    <p>-t  Exit after reading and executing one command. </p>
  </blockquote>
  
  <p>I tried a couple of different tests:</p>
  
  <p>For this one there was <em>no</em> output to the terminal</p>
  
  <pre><code>#!/usr/bin/env bash
  
  set -t
  
  echo "test"
  </code></pre>
  
  <p>For this one running it and then running <code>echo $TEST_VAR</code> from the terminal shows <code>$TEST_VAR</code> is empty</p>
  
  <pre><code>#!/usr/bin/env bash
  
  set -t
  
  export TEST_VAR="test"
  </code></pre>
  
  <p>What does <code>set -t</code> really do and what is an example of how it can be used?</p>