title: execute bash script from php without waiting
body: <p>I execute a bash script from php with shell_exec.
  But the php script waits until the shell script is finished. </p>
  
  <p>Can I somehow call the bash script without waiting.
  Both:</p>
  
  <pre><code>exec
  shell_exec
  </code></pre>
  
  <p>are waiting until the bash script is finished.
  I'm running linux btw.</p>