16比较暂存区和HEAD所含文件的差异

背景

在git仓库中，我们将暂存区的文件提交前还需要判断暂存区文件和HEAD所含文件的差异，判断是否能够作为新的提交。

实践

我们修改git仓库的readme文件：

 G:\mygitea\GitLearn\learn03   master ± 
$ vim readme

 G:\mygitea\GitLearn\learn03   master ± 
$ git status
On branch master
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
        modified:   readme

no changes added to commit (use "git add" and/or "git commit -a")

 G:\mygitea\GitLearn\learn03   master ± 
$ git add readme

 G:\mygitea\GitLearn\learn03   master ± 
$ git diff --cached
diff --git a/readme b/readme
index 93d277f..d371e8e 100644
--- a/readme
+++ b/readme
@@ -2,3 +2,4 @@ This is the oldest branch.
 This is the older branch.
 This is the young branch.
 after test, update readme.
+test HEAD and cached compare.