title: How to restart some progress which is stopped by "ctrl+z"?
body: <p>When I am using </p>
  
  <pre><code>postgres -D /usr/local/pgsql/data 
  </code></pre>
  
  <p>to start the <code>postgresql</code> progress, I send a <code>ctrl+z</code> signal to stop it.<br/>
  And now when I used <code>createuser</code> and <code>psql</code>, it has no response.</p>
  
  <p>what can I do？</p>