Github在repo中添加其它repo: adding embedded git repository

最近整理github资源 发现没法将另外github repo上传过去，后来发现使用git submodule可以添加

核心命令git submodule add <url> index

git submodule add https://github.com/DengSchoo/OnJava8-zh LanguageFoundation/Java8/OnJava8-resource/OnJava8-zh

如果发现该索引已经存在：

fatal: 'LanguageFoundation/Java8/OnJava8-resource/OnJava8-zh' already exists in the index

则需要删除缓存:

git rm -r --cached LanguageFoundation/Java8/OnJava8-resource/OnJava8-zh