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When commits are squashed by git rebase --interactive (git rebase -i), the author of the squashed commit will be the author of the first squashed commit.
For example, suppose that we want to squash four commits of A, B, C, and D in master branch.
By executing git rebase --interactive HEAD~4, vim (or one specified by GIT_EDITOR or git config core.editor) will appear with the following text:
pick 10d7eee commit A
pick 88e7a36 commit B
pick 5d54325 commit C
pick 6e374dc commit D
Squash B, C, and D into A (here I use fixup instead of squash):
pick 10d7eee commit A
fixup 88e7a36 commit B
fixup 5d54325 commit C
fixup 6e374dc commit D
then the author will be "Alan Adelman", the author of A.
https://github.com/wataash/git-test-squash/commits/squash-into-a
git show squash-into-a:
commit 8e61e787fed78bdab3abd47527f3c65d363f1ff0 (origin/squash-into-a, squash-into-a)
Author: Alan Adleman <[email protected]>
Date: Sat Apr 14 12:34:47 2018 +0900
commit A
If we want "Donald Dijkstra" (author of D) survive as the author, simply move "commit D" to the top then squash the others:
pick 6e374dc commit D
fixup 10d7eee commit A
fixup 88e7a36 commit B
fixup 5d54325 commit C
Yielding the result as wishes.
https://github.com/wataash/git-test-squash/commits/squash-into-d
git show squash-into-d:
commit 6116c585cfba2a9599b5dc0a11aaf27d24bae7fe (origin/squash-into-d, squash-into-d)
Author: Donald Dijkstra <[email protected]>
Date: Sat Apr 14 12:55:11 2018 +0900
commit D
If commit D conflicts with the others while reordering of the commits, we can rewrite the author by git commit --author='Donald Dijkstra <[email protected]>' --amend --no-edit after squashing into A, without reordering. git commit --author=$(git log '--format=%an <%ae>' -1 6e374dc) --amend --no-edit is better to prevent typo.
(~4 means parent of parent of parent of parent of HEAD, so HEAD~4 is equivalent to 79e9533. So as HEAD~~~~. See git-rev-parse(1) for details.)