git diff : compare working directory and staged file ( by git add)
git diff --stage: compare staged file with file on the server
git diff HEAD: compare working directory and file on the server
git diff ffd98b291e0caa6c33575c1ef465eae661ce40c9:filename b8e7b00c02b95b320f14b625663fdecf2d63e74c:filename (filename 是带路径的，或者是 如 ./a.out 这样的形式）
git show $commit --stat : show which files included for $commit
git log -p file : show commit history for file
git log --pretty=oneline file : show related commits that includes the file
git log --author=daphne :查看某个用户的提交记录
git show <commit> <file> : show the file include in the commit
git stash list //查看stash 列表
执行 git stash clear :注意这是清空你所有的内容
git stash drop stash@{0} 这是删除第一个队列