May 04, 2021

How to edit stuff that you've already commited to git? (And squash as a bonus)

So, you’re in the middle of a review, and have couple of commits but one of the comments is asking you to modify a line that belongs to second to last, or even the first commit in your list, and you’re not willing to do:

git commit -m "Add fixes from the review" $file

Or you simply don’t know, and have no idea what squash or rebase means?, well I won’t explain rebase today, but I will explain rebase

DON'T PANIC

See how I do it, and also how do I screw up!

asciicast

It all boils down to making sure that you trust git, and hope that things are small enough so that if you lose the stash, you can always rewrite it.

So in the end, for me it was:

git fetch origin
git rebase -i origin/master # if your branch is not clean, git will complain and stop
git stash # because my branch was not clean, and my desired change was already done
git rebase -i origin/master # now, let's do a rebase
# edit desired commits, for this add the edit (or an e) before the commit
# save and quit vim ([esc]+[:][x] or [esc]+[:][w][q], or your editor, if you're using something else
git stash pop # because I already had my change
$HACK # if you get conflicts or if you want to modify more
      # be careful here, if you rewrite history too much
      # you will end up in Back to the Future II
      # Luckly you can do git rebase --abort
git commit --amend $files #(alternatively, git add $files first then git commit --amend
git rebase --continue
git push -f # I think you will need to add remote+branch, git will remind you
# go on with your life

(Note: A squash is gonna put all of the commits together, just make sure that there’s an order:

  • pick COMMIT1
  • pick COMMIT2
  • squash COMMIT3 # (Git will combine this commit, with the one above iir, so COMMIT2+COMMIT3 and git will ask you for a new commit message)