title: How can I insert and retrieve a custom field into a .gitconfig file?
body: <p>I have the following .gitconfig:</p>
  <pre><code>[user]
  name = name
  email = email@email.com
  custom_field = AAA
  </code></pre>
  <p>Getting name and email is easy using <code>git config</code>.</p>
  <p>How can I get the value of custom_field :</p>
  <pre><code>$ git config --global user.custom_field 
  error: invalid key: user.custom_field
  </code></pre>