<p> 如何在基于回调的函数（如child_process.exec）中使用promise API？( )</p>
<p> new Promise(child_process.exec())</p>
<p> util.promisify(child_process.exec())</p>
<p> util.promisify(child_process.exec)</p>
<p> new Promise(child_process.exec)</p>
