git: update commit message

To change the last commit message, use commit with the --amend flag:

Careful: commit --amend will rewrite history; do not use it on public branches.

git commit --amend

It will open an editor to change the commit message. The changes will be applied after saving the file and closing the editor.

Besides other things, interactive rebase allows editing commit messages:

git rebase -i HEAD~3

pick SHA-A commit message
pick SHA-B commit message
pick SHA-C commit message

Do not change commit messages just yet, only change pick in the first column to r (or the full reword):

pick SHA-A commit message
r SHA-B commit message
r SHA-C commit message

Here we schedule a commit message update for the SHA-B and SHA-C commits. After the file is saved, git will open the editor once more for each of the marked commits, where we can edit the commit message.

This might be useful if we want to pick some commits from the branch and update commit messages:

# create the new branch
git checkout -b new-branch

# for every commit to pick
git cherry-pick commit-sha
git commit --amend

So we cherry-pick the needed commits and then edit commit messages with commit --amend.