title: After git checkout file from commit, git diff shows no changes?
body: <p>I am confused on the git checkout  behavior.  If I wanted to grab a previous version of the file and do something like:</p>
  
  <pre><code>git checkout HEAD^^ Xml/Config-Profile.xml
  git status
  </code></pre>
  
  <p>I get:</p>
  
  <pre><code>On branch master
  Your branch is up-to-date with 'origin/master'
  
  Changes to be committed:
    (use "git reset HEAD &lt;file&gt;..." to unstage)
  
      modified: Xml/Config-Profile.xml
  </code></pre>
  
  <p>And if I do, git diff, I get no differences.  I've figured out that if I do git diff --cached, it shows the changes, so I guess that means that my checkout command pulled from repository's HEAD^^ commit and updated the 'index only'?</p>
  
  <p>I guess my concerns are (and I couldn't gleam info directly from checkout manual pages):</p>
  
  <p>1) Why is only the index getting updated?  How come it doesn't behave as if I just replaced the Config-Profile.xml file in my <strong>working directory</strong> with some (previous) copy of the file?</p>
  
  <p>2) I guess what makes this confusing for me, and maybe it is all just semantics, is that if I were editing a file in my working directory and decided I didn't like it and did a git checkout, it replacing the file in the working directory.  After stating that, I'm guessing that git checkout pulls latest file from the index into the working directory, instead of the file from the latest commit in the repository?</p>
  
  <p>3) Is there a command that pulls a file from a commit directly into the working directory as if I edited it myself manually to that point?  Or do I need to create a custom alias?</p>
  
  <p>Thanks in advance.</p>