title: Git - some files are marked as changed but 'git diff' doesn't show anything
body: <p>I am quite new to Git, thus maybe I am missing something here.</p>
  
  <pre><code>dan@one:/var/www/$ git status -s
  M  GoogleChromeExtension.js
  M  ApiClient.js
  </code></pre>
  
  <p>So clearly 2 files have been changed.<br>
  But when I run:</p>
  
  <pre><code>git diff
  </code></pre>
  
  <p>no output is shown. I was expecting to get the changes between my working copy and the latest commit.</p>
  
  <p>I am sure yesterday everything was working as expecting...</p>
  
  <p>Is it maybe because I haven't been pushing the changes to the remote server?  </p>
  
  <p>P.S.: I am using GitHub</p>
  
  <p>Thanks,<br>
  Dan</p>