git-commit-amend

The git commit --amend command is a convenient way to modify the most recent commit.

It lets you combine staged changes with the previous commit instead of creating an entirely new commit. It can also be used to simply edit the previous commit message without changing its snapshot. In fact, amending does not just alter the most recent commit, it replaces it entirely, meaning the amended commit will be a new entity with its own ref.

revise recent commit message

This is common, as premature commit happens all the time.

git commit --amend -m "an updated commit message"

change committed content

It is also common that some file is forgotten in previous commit.

git add <forgotten-file>
git commit --amend --no-edit

Note the --no-edit option is used to tell git there’s no need to change the original commit messager, just add the file.

push to remote

If you haven’t pushed the last commit yet to your remote, a simple regular push is enough.

Otherwise, you must push with -f option because you’ve rewritten your commit history.

git push -f origin <branch-name>

Note: Always, use commit amend option cautiously, and, NEVER rewrite the commit history of public/team branches (like master). This will truly mess your teammates work. I personally only allow commit rewrite in individual feature branches to regulate premature or mistaken commits before merging to main branches.

change even older or multiple commits

To modify older or multiple commits, --amend is no longer userful. Git rebase is the only way to combine a sequence of commits into a new base commit, which literally rewrite history. Check out git-rebase page.