如何在LUA脚本中正确格式化日期-05292020

我在这个LUA脚本中遇到了一些日期格式化的困难。我想以以下格式输出当前日期-05292020。但是，我无法正确格式化年份，因此我的输出是052920。我一直在广泛搜索，希望找到解决方案，但我真的卡在了这里。有人能指点我一下吗？先感谢您！

function OnEvent(event, arg, family)
  if event == "G_PRESSED" and arg == 1 then

    -- 只取前8个字符(1,8)
    local date = string.sub(GetDate(), 1, 8)
    for i = 1, #date do
      local ch = date:sub(i,i)
      if ch == "-" then
        PressAndReleaseKey("minus")
      elseif ch == "," then
        PressAndReleaseKey("comma")
      elseif ch == "." then
        PressAndReleaseKey("period")
      elseif ch == "/" then
      --  PressAndReleaseKey("slash")
      elseif ch == " " then
        PressAndReleaseKey("spacebar")
      elseif ch == ":" then
        PressKey("lshift")
        Sleep(10)
        PressAndReleaseKey("semicolon")
        ReleaseKey("lshift")
      elseif ch == ch:lower() then
        PressAndReleaseKey(ch)
      else
        PressKey("lshift")
        Sleep(10)
        PressAndReleaseKey(ch:lower())
        ReleaseKey("lshift")
      end
    end

  end
end