useradd命令的-K参数如何理解

useradd命令的-K参数怎么理解？
man里的英文，看不懂，还提到了user_attr（4），更是晕了，请简单描述（中文最好），给个例子更妙！

[解决办法]
-k skel_dir
A directory that contains skeleton information (such as .profile) that can be copied into a new user's home directory. This directory must already exist. The system provides the /etc/skel directory that can be used for this purpose.

就是为新建的用户拷贝创建一些默认的文件。