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

最近整理github資源 發現沒法將另外github repo上傳過去，后來發現使用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

如果發現該索引已經存在：

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

則需要刪除緩存:

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