Not today...

This post is a simple copy of this answer, go there to see the original.

As I am using git extensively in my day to day life/job, I encountered the issue to simply amend a commit which is already two or three commits before the current one.

I could use git rebase -i with some stashing to apply the changes at the proper moment. This is most of the time a viable solution, however, it may be complicated because I have too much new code and stashing would be complicated.

So another solution is to create a simple commit with only the changes I want to apply to the old commit, and then run some magic to apply it at the proper moment.

Here is the flow:

# add the changes you want to see there
git add -p

# find the hash your are looking for (use part of this command to see what happens)
export OLDCOMMIT=$(git log --oneline | sed -e 's/ .*//g' -e '3q;d')

# create a commit with it on top of your stack with a proper reference
git commit --fixup=${OLDCOMMIT}

# you will may need to stash the rest of the changes
git stash

# now rework the history to apply the change
git rebase --interactive --autosquash "${OLDCOMMIT}^"