HEAD：当前检出位置与 Symbolic Reference | Git
本章覆盖：HEAD points to branch；symbolic reference；current commit；`HEAD~`；`HEAD^`；ancestor notation；detached HEAD；checkout commit；commits in detached HEAD；creating branch to retain detached work。
本章知识点
- HEAD points to branch
- symbolic reference
- current commit
HEAD~HEAD^- ancestor notation
- detached HEAD
- checkout commit
- commits in detached HEAD
- creating branch to retain detached work