git diff在.gitignore中但已添加以进行跟踪的文件上

Question

For a file

config/config.py

That file is in .gitignore I need to make changes to add to my own clone. However it is not desirable to change the .gitignore itself: we want most users not to see this file.

So I did

git add -f config/config.py

However

git diff config/config.py

shows nothing.

Correction I had stated in original version that

git status

shows nothing: that is not true it does show

new file:   config/config.py

So it appears the surprise were only with the git diff command?

(Off topic a bit: generally the whole .gitignore / tracked vs untracked is a surprisingly tricky/painful process. I have looked at a number of SOF's on this topic and they do not lend confidence here.)

Answer 1

git diff shows the difference between the staging area (aka index) and the working tree. You have just added your file to the staging area, so it is perfectly normal that git diff shows nothing. You want to run

git diff HEAD

instead. This will show the diff between the file and HEAD which means "the last commit". If the file was not present in HEAD , then the diff will show the whole file.

It seems that you ran git rm --cached and did a commit previously, hence the file is not there in HEAD . You did a mistake previously, and trying to repair this mistake can be more dangerous if you do not understand what you are doing. If you want to try, then learn about rewriting history in Git.

If you want to see the diff with a commit past in history, then run

git diff <commit-id>

This is completely unrelated from the fact that the file is in .gitignore .