3

The index is the staging area right?

From the git docs:

git diff

Let’s stop for a minute to see how the git diff command can be used to show you the difference between the version of a file in the working directory, index and most recent commit. The 3 main types of git diff commands you would likely use are:

git diff: Show differences between your working directory and the index.
git diff –-cached: Show differences between the index and the most recent commit.
git diff HEAD: Show the differences between your working directory and the most recent commit.

My question is in regards to git diff. The thing is is that I didn't commit anything or git add anything yet and the changes in my working directory are shown when I type in git diff. My staging area is empty. when I type in git status, I see two files in red that will not be staged since I didn't use git add yet. So why does git diff show the changes I made in my working directory?

Improve this question
3
  • 1
    Regarding "My staging area is empty": it's never empty. After a commit, your staging area and your most recent commit match. For files that are committed, git add replaces the existing index copy of the file(s) with the ones from the work-tree. For new ("untracked") files, git add puts them into the index, and now they are "tracked" (but not yet committed). ("Never" is a slight overstatement: if you remove all files and commit, your commit and your index are both empty.) Commented Jun 14, 2016 at 21:30
  • Interesting... any reason why you're using both "index" and "staging" area? Also if you git add file A, and then run git diff, I should see any changes from File A show up since file A is now in the index. But why does it show up as a change? If file A is now in the index and in my CWD, there's no difference? Commented Jun 15, 2016 at 15:41
  • "Index" and "staging area" are two terms for the same thing (the underlying file is named .git/index but "index" is a poor name, so it acquired a new one). As for git add A: if git diff compares index-vs-work-tree, and you copy file A from the work-tree into the index, what difference do you now expect to see, between "index copy of A" and "work-tree copy of A"? There may have been a difference before you copied, but why would you expect a difference now? Commented Jun 15, 2016 at 20:05

1 Answer 1

Reset to default
5

git diff: Show differences between your working directory and the index.

Working directory: your current code, even files that were not staged yet.

Index: You are right, this is the staging area.

When you do a git diff, it compares your current code with the staging area, which is precisely the behavior you described.

From the git documentation:

git diff

This form is to view the changes you made relative to the index (staging area for the next commit). In other words, the differences are what you could tell Git to further add to the index but you still haven’t. You can stage these changes by using git-add[1].

So, we have 3 different situations:

1 - You have no changes not staged -> git diff shows nothing.

2 - You have some changes staged, some not staged -> git diff shows the diff between your CWD and staging area.

3 - Stage area empty, some changes -> git diff shows diff between CWD and the last commit.

Improve this answer
Sign up to request clarification or add additional context in comments.

2 Comments

Why is this? You'd think git diff would compared your CWD with HEAD? Also, if nothing is in my staging area... what is it comparing it to? I'm confused because I didn't add anything yet but git diff is showing me changes between what seems to be my CWD and HEAD
I've added some info to my answer, hope it makes it clearer

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.