<% Global.username %>
macro checks if the current session is authenticated if true it returns the username

Sourcecode in Global/macros.js:
1:   function username_macro(param) {
2:      if (!session.user)
3:         return;
4:      if (session.user.url && param.as == "link")
5:         Html.link({href: session.user.url}, session.user.name);
6:      else
7:         res.write(session.user.name);
8:      return;
9:   }