title: mode: 0o666 in file system methods, what is it?
body: <p><a href="https://nodejs.org/api/fs.html#fs_fs_createwritestream_path_options" rel="noreferrer">https://nodejs.org/api/fs.html#fs_fs_createwritestream_path_options</a></p>
  
  <p>It mentions the option <code>mode</code> with the value <code>0o666</code>. As you can read if you click the link there is no real description of what this.</p>
  
  <p>I am presuming it is the file permission to be set. However I'm not used to seeing <code>0o666</code>. Am I correct that it is the file permission and if so, what does <code>0o666</code> stand for?</p>