title: what's the usage of 'bind' in bash
body: <p>I found something in a <code>.bashrc</code> file like:</p>
  
  <pre><code>bind '"\C-j": menu-complete'
  bind 'set completion-ignore-case on'
  </code></pre>
  
  <p>if I remove the 'bind',the result seems no different, so what's the usage of the 'bind' here?</p>