title: How to print current files on git index?
body: <p>I can print the currently committed tree with:</p>
  
  <pre><code>git cat-file -p master^{tree}
  
  100644 blob 8fe01e69e28f7c6997c0f5372c015363947582d8    .angular-cli.json
  100644 blob 6975847ed5aa229532141a971337caca0a401451    .dockerignore
  100644 blob 1f354482f8681a1b017bc4fdde17a4802e84b06a    .editorconfig
  100644 blob 9c4b02c9bd7338416bcb4037c5d5fac4c116bca5    .env.example
  040000 tree d9e02522647d4f28dc40f62dca564afa48fba019    .github
  </code></pre>
  
  <p>I'm now looking to know how to print files in my current index, staged files? <strong>I'm looking for a low-level command like <code>git cat-file</code> and not for a high-level command.</strong></p>
  
  <p>I see there is this <code>index</code> file:</p>
  
  <pre><code>ls .git/index 
  .git/index
  </code></pre>
  
  <p>But what is the command to print its content (again low-level command, with an argument to this file)?</p>