title: How to print initial letter of committer in git log?
body: <p>I have prepared an alias to get a short log report in git</p>
  
  <pre><code># excerpt from ~/.gitconfig
  [alias]
      lg = log --all --oneline --graph --decorate --pretty='%C(auto)%h %Cgreen%ai %C(reset)%C(auto)%s %d'
  </code></pre>
  
  <p><code>git lg</code> generates one nice line per commit, but without information on the user:</p>
  
  <pre><code>* 623beff 2016-11-14 14:18:36 +0100 extended plotstyle option and automatic colors
  </code></pre>
  
  <p>or as screenshot:</p>
  
  <p><a href="https://i.stack.imgur.com/jqkIg.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/jqkIg.png" alt="example screenshot"></a></p>
  
  <p><strong>But</strong> I want to see the <strong>initial letters of the committer real name</strong> (the full name is sometimes too long) in each line:</p>
  
  <pre><code>* 623beff 2016-11-14 14:18:36 +0100 (J.S.) extended plotstyle option and automatic colors
  </code></pre>
  
  <p>How can I get this result?</p>