Good commit messages serve at least three important purposes:
- To speed up the reviewing process.
- To find out what changed in a range of commits (e.g. for a release note).
- To help the future maintainers, say five years into the future, to find out why a particular change was made to the code or why a specific feature was added.
Structure your commit message like this:
From: https://git-scm.com/book/ch5-2.html
Short (50 chars or less) summary of changes
More detailed explanatory text, if necessary. Wrap it to
about 72 characters or so. In some contexts, the first
line is treated as the subject of an email and the rest of
the text as the body. The blank line separating the
summary from the body is critical (unless you omit the body
entirely); tools like rebase can get confused if you run
the two together.
Further paragraphs come after blank lines.
- Bullet points are okay, too
- Typically a hyphen or asterisk is used for the bullet,
preceded by a single space, with blank lines in
between, but conventions vary here
An example of a good commit message:
Redirect user to the requested page after login
https://trello.com/path/to/relevant/card
Users were being redirected to the home page after login, which is less
useful than redirecting to the page they had originally requested before
being redirected to the login form.
- Write the summary line and description of what you have done in the imperative mode, that is as if you were commanding someone. Start the line with "Fix", "Add", "Change" instead of "Fixed", "Added", "Changed".
- Always leave the second line blank.
- Line break the commit message (to make the commit message readable without having to scroll horizontally in gitk).
- Don't end the summary line with a period - it's a title and titles don't end with a period.
- Just like with the Single Responsibility Principle in your code, if it seems
difficult to summarize what your commit does, it may be because it includes
several logical changes or bug fixes. Split it up into several commits using
git add -por using a GUI such as GitHub desktop. - Typing multiline commit messages isn't the most pleasant thing to do via the
command line, so tell git to use your editor when doing
git commit. Find out how to here: https://help.github.com/en/articles/associating-text-editors-with-git.
- "On commit messages": https://who-t.blogspot.com/2009/12/on-commit-messages.html
- Tim Pope of Vim plugin infamy on commit messages: "A Note About Git Commit Messages": https://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html
- "How to Write a Git Commit Message": https://chris.beams.io/posts/git-commit/