What are the differences between the following git commands?
git diff HEADgit diff HEAD^git diff --cachedor the synonymgit diff --stagedgit diff
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5 Answers
git diff HEAD- Shows what has changed since the last commit.git diff HEAD^- Shows what has changed since the commit before the latest commit.git diff --cached- Show what has been added to the index viagit addbut not yet committed.git diff- Show what has changed but hasn't been added to the index yet viagit add.
It looks like this:
Working Directory <----+--------+------+ | | | | | | | | V | | | "git add" | | | | diff | | | | | | V | | | Index <----+ diff HEAD | | | | | | | | | V | | | "git commit" | | | | diff --cached | | | diff --staged | | V | | | HEAD <----+--------+ | | | | diff HEAD^ V | previous "git commit" | | | | | V | HEAD^ <--------------------+ 
7 Comments
takeshin
@Picasso Is it hand drawn or did you used some ASCII art tool? Is there any git command for this too? ;)
Amber
@takeshin: Hand-drawn; it's not that hard. (But there is an emacs mode for drawing ascii art, not that I use it.)
thalisk
+1 for the ascii-art alone. One image = 1000 words; One ascii-art = 1025 chars.
dkjain
git diff - Show what has changed but hasn't been added to the index yet via git add. : this isn't entirely correct, if working directory (WD), IDX and HEAD are not equal then git diff will show changes from IDX(red) -> WD(green), pls correct if I'm wrong.
aderchox
Something's confusing! "git add" alone doesn't change the files so there musn't be really a difference shown by "git diff" according to the diagram above... . It seems that git diff shows the difference between the working directory and the last commit... Am I wrong?
Haris
The diagram is confusing for me as well. If any file is changed in the working directory, and it's still not staged, "git diff" shows those changes. So yes, it seems that git diff shows the difference between the working directory and the last commit.
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From the Git Community Book:
git diff
will show you changes in the working directory that are not yet staged for the next commit.
git diff --cached
will show you the difference between the index and your last commit; what you would be committing if you run "git commit" without the "-a" option.
git diff HEAD
shows changes in the working directory since your last commit; what you would be committing if you run "git commit -a".
Comments
git diff HEAD: Diff between HEAD and the working directory.git diff HEAD^: Diff between the direct ancestor of HEAD and the working directory.git diff --cachedor the synonymgit diff --staged: Diff between HEAD and the index.git diff: Diff between the index and the working directory.
5 Comments
Kevin Wheeler
Does anyone have a good way to remember this? I keep coming back here.
aderchox
Could you please tell me why should index and working directory be different? "git add <file>" doesn't change the file! It seems to me that git diff shows the difference between the working directory and the last commit... . I'm not sure though.
wRAR
@Narnia
git add <file> changes the file in the index. It's hard to explain the index in the comments.aderchox
@wRAR Then would you please ask the proper question and answer it yourself? (It is allowed and even AFAIK recommended by SO).
wRAR
@Narnia see e.g. stackoverflow.com/questions/3689838/…
Here's a simple way to remember these commands:
- By default,
git diff's source is assumed to be the working directory, and its target is the index. - Adding the
--cachedflag changes the source to be the index. It doesn't necessarily change the target once you add more arguments. But for convenience the target becomes the last commit if none is provided. - Adding a commit as an argument changes the target.
- Adding two commits as arguments changes both the source and the target, respectively.
Have fun mixing them up to your own liking :)
Comments
HEAD is the current HEAD pointer in the tree, HEAD^ is the commit before HEAD. --cached I'm not sure about.--cached will show you any changes you have made but haven't added to the index.
The git tutorial on kernal.org is a very good read.
1 Comment
Amber
You got
--cached slightly wrong: it shows you only changes that you have added to the index (but haven't committed).