Add More Files and Changes to a Commit Before Pushing

To add more files to the most recent commit, we can add them to the staging area with:

git add -A

and then rewrite the most recent commit to include them with:

git commit --amend -m "My new message"

Caution: only do this BEFORE you've pushed the commits - otherwise you will be re-writing history for people who may have already pulled down the old commits.