> git init .
Initialized empty Git repository in /home/XXXXX/test/.git/
> ll
total
> touch foo
> git add foo
> git commit -m init
[master (root-commit) cdc99b4] init
1 file changed, 0 insertions(+), 0 deletions(-)
create mode 100644 foo
> echo "bar">foo
> git log
commit cdc99b4fa8cd2117015cd114bf269ab9a209e58c
Date: Thu Jan 28 08:57:34 2016 +0100
init
Change-Id: If5530860db17d2242e4082666042960fc423f737
> git diff --cached cdc99b4fa8cd2117015cd114bf269ab9a209e58c
> cat foo
bar
> git status
# On branch master
# Changes not staged for commit:
# (use "git add <file>..." to update what will be committed)
# (use "git checkout -- <file>..." to discard changes in working directory)
#
# modified: foo
#
no changes added to commit (use "git add" and/or "git commit -a")
>The expected result is that git diff can output bar
滿天的星座2017-05-02 09:29:13
git diff --cached
Explain, git diff 对比的是 working tree 和 HEAD 之间的。而你这个应该是 git add 之后了，所以需要对比 staged 和 HEAD 之间，加 --cachedThat’s what it’s for.
OK, I didn’t read the process in the question carefully before, so the above answer is wrong. Thanks to @jokester for reminding me.
Then I reproduced the process of asking the question, and the results are as follows:
The result is git diff There is no problem. In order to ensure that there are no omissions in the entire process, a complete screenshot is attached. The questioner can compare it to see where the problem is.
In addition, I noticed that the questioner used the foo 之后没有 git add 的情况下使用的是 git diff --cached 命令，这恰恰符合我之前答案提到的（我是理解反了题目的诉求），所以不要加 --cached command after re-editing foo without git add, which is exactly in line with what I mentioned in the previous answer (I am This is contrary to the question's appeal), so just don't add --cached. Attached is a comparison:
