title: Meteor read file sync issue
body: <p>I have issue with meteor app deployed with yamup in Ubuntu.</p>
  
  <pre><code>const tmpFilePath = Meteor.settings['DOWNLOADS_PATH'] + '/tmp/' + fileName;
      wkhtmltopdf(html, { pageSize: 'A4', encoding: 'utf-8' })
          .pipe(fs.createWriteStream(tmpFilePath))
          .on('error', (err) =&gt; {
              future.return({ err, buffer: null });
          }).on('close', () =&gt; {
              # here occur issue #
              const buffer = fs.readFileSync(tmpFilePath);
              fs.unlinkSync(tmpFilePath);
              future.return({ err: null, buffer });
          });
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/Dwcwq.png" rel="nofollow noreferrer">enter image description here</a>
  tmp file is generated on tmp directory with root permission, but can not read and write sync.
  What is solutions?</p>