title: shell_exec() unable to execute certain commands
body: <p>I was just testing and fiddling around with security stuff when I noticed that I cannot get a result from the following:</p>
  
  <pre><code>&lt;?php echo shell_exec('history'); ?&gt;
  </code></pre>
  
  <p>The same refers to:</p>
  
  <pre><code>&lt;?php echo shell_exec('fc -l 1'); ?&gt;
  </code></pre>
  
  <p>Both have been tried with <code>2&gt;&amp;1</code> at the end but after all - <code>history</code> is not a command. Tried under CLI as well:</p>
  
  <pre><code>php -r "echo shell_exec('fc -l 1');"
  </code></pre>
  
  <p>which does not return anything. Has been attempted with <code>system()</code> and <code>exec()</code> also (=does not return a result). In the same time:</p>
  
  <ul>
  <li>I can execute both <code>history</code> and <code>fc -l 1</code> via SSH;</li>
  <li>I can execute other commands such as <code>ls</code> via PHP (<code>shell_exec()</code> both on web and in CLI);</li>
  <li>I am running the same user;</li>
  <li><code>history</code> and <code>fc -l 1</code> do return results;</li>
  </ul>