Git: Oops I forgot to add this thingy

Here’s a situation that happens often during development:

Suppose you committed something to git. A few commits later, you realized you forgot to add something to that commit, or possibly missed a link, or even spotted a typo. How do you go about fixing it?

Team

If you’re working on a repository with a team, you should just git commit and git push. Write an eloquent commit message to refer to the previous commit in which you forgot to include your changes.

Self

Now, if you’re working on a standalone repository, just for yourself¹, this creates an opportunity to rewrite your history in a cleaner way. The workflow is as follows:

1. Make the changes or fixes you had originally forgot to.
2. git add them.
3. Identify the commit id in which you originally wanted to make those changes. git log or tig are simple CLI-oriented ways to do so. Hereafter assume this id is abcdef.
4. Commit your changes while referencing the original commit and then rewrite history:

$ git commit --fixup=abcdef

# Then pick one of:
$ git rebase -i --root
$ git rebase -i abcdef~1

# And then save the file as is.

5. Double-check everything went as expected with git log and/or git show and/or tig.
6. If you’re happy with the current state of your repository, commit the sin: git push --force.

References

• tig, in case you don’t know:

tig is an ncurses-based text-mode interface for git. It functions mainly as a Git repository browser, but can also assist in staging changes for commit at chunk level and act as a pager for output from various Git commands.

• git rebase --root: c.f. Stack Overflow. This is just a lazy way to make the rebase include abcdef. You could do something like git rebase -i HEAD~10 where 10 is an arbitrary guess, but this will only work if abcdef is within the most 10 recent commits. Alternatively git rebase -i abcdef~1 also works.