git: 提交前查看修改 git diff，HEAD^, HEAD~i

参考：

https://blog.csdn.net/GW569453350game/article/details/46998395

https://lijunde.blog.csdn.net/article/details/88798254?spm=1001.2101.3001.6661.1&utm_medium=distribute.pc_relevant_t0.none-task-blog-2%7Edefault%7EBlogCommendFromBaidu%7ERate-1-88798254-blog-46998395.pc_relevant_vip_default&depth_1-utm_source=distribute.pc_relevant_t0.none-task-blog-2%7Edefault%7EBlogCommendFromBaidu%7ERate-1-88798254-blog-46998395.pc_relevant_vip_default&utm_relevant_index=1

https://blog.csdn.net/claroja/article/details/78858411?spm=1001.2101.3001.6650.1&utm_medium=distribute.pc_relevant.none-task-blog-2%7Edefault%7EBlogCommendFromBaidu%7ERate-1-78858411-blog-46998395.pc_relevant_vip_default&depth_1-utm_source=distribute.pc_relevant.none-task-blog-2%7Edefault%7EBlogCommendFromBaidu%7ERate-1-78858411-blog-46998395.pc_relevant_vip_default&utm_relevant_index=2