Question:
I have a file a.txt.
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cat a.txt > hello |
The contents of a.txt is “hello”.
I make a commit.
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git add a.txt git commit -m "first commit" |
I then move a.txt into a test dir.
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mkdir test mv a.txt test |
I then make my second commit.
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git add -A git commit -m "second commit" |
Finally, I edit a.txt to say “goodbye” instead.
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cat a.txt > goodbye |
I make my last commit.
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git add a.txt git commit -m "final commit" |
Now here is my question:
How do I diff the contents of a.txt between my last commit and my first commit?
I’ve tried:
git diff HEAD^^..HEAD -M a.txt, but that didn’t work. git log --follow a.txt properly detects the rename, but I can’t find an equivalent for git diff. Is there one?
Answer:
The issue with the difference between HEAD^^ and HEAD is that you have an a.txt in both commits, so just considering those two commits (which is what diff does), there is no rename, there is a copy and a change.
To detect copies, you can use -C:
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git diff -C HEAD^^ HEAD |
Result:
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index ce01362..dd7e1c6 100644 --- a/a.txt +++ b/a.txt @@ -1 +1 @@ -hello +goodbye diff --git a/a.txt b/test/a.txt similarity index 100% copy from a.txt copy to test/a.txt |
Incidentally, if you restrict your diff to just one path (as you do in git diff HEAD^^ HEAD a.txt you aren’t ever going to see the renames or copies because you’ve excluded the everything apart from a single path and renames or copies – by definition – involve two paths.