git-good-commit

Git hook to help you write good commit messages.

Validates commit messages conform to six of the seven rules of a great git commit message, plus a couple of extras:

1. Separate subject from body with a blank line
2. Limit the subject line to 50 characters
3. Capitalize the subject line
4. Do not end the subject line with a period
5. Use the imperative mood in the subject line
6. Wrap the body at 72 characters
7. Use the body to explain what and why vs. how - you're on your own with this one
8. Do no write single worded commits
9. Do not start the subject line with whitespace

Offers an interactive prompt if any of the rules are detected to be broken.

Installation

Single repository

At the root of the repository, run:

curl -L https://raw.githubusercontent.com/tommarshall/git-good-commit/v0.7.0/hook.sh > .git/hooks/commit-msg && chmod +x .git/hooks/commit-msg

Globally

To use the hook globally, you can use git-init's template directory:

mkdir -p ~/.git-template/hooks
git config --global init.templatedir '~/.git-template'
curl -L https://raw.githubusercontent.com/tommarshall/git-good-commit/v0.7.0/hook.sh > ~/.git-template/hooks/commit-msg && chmod +x ~/.git-template/hooks/commit-msg

The hook will now be present after any git init or git clone. You can safely re-run git init on any existing repositories to add the hook there.

Alternative: a single global hook

Alternatively, core.hooksPath (Git 2.9+) points every repository at one shared hooks directory, so there's only a single copy to maintain:

mkdir -p ~/.git-hooks
curl -L https://raw.githubusercontent.com/tommarshall/git-good-commit/v0.7.0/hook.sh > ~/.git-hooks/commit-msg && chmod +x ~/.git-hooks/commit-msg
git config --global core.hooksPath ~/.git-hooks

Unlike the template approach, this applies to repositories you've already cloned, and updates in one place. Note that core.hooksPath replaces each repository's .git/hooks, so any other hooks — including those installed by tools like Husky, pre-commit or lefthook — won't run unless you also add them to ~/.git-hooks.

---

If you're security conscious, you may be reasonably suspicious of curling executable files. In this case you're on HTTPS throughout, and not piping directly to execution, so you can check contents and the hash against MD5 d25310de1598dbc784539dabaf12cd51 for v0.7.0.

Usage

echo "apple" > ./bar.txt
git add fruits.txt

# should warn you that the subject line is not capitalised, and offer an interactive prompt.
git commit -m 'add fruits.txt'

Options

e - edit commit message
y - proceed with commit
n - abort commit
? - print help

Configuration

The default colour setting is auto, but the hook will use git's color.ui config setting if defined. You override the colour setting for the hook with:

git config --global hooks.goodcommit.color "never"

Supported values are always, auto, never and false.

Dependencies

None, other than Bash.

Credits

• http://chris.beams.io/posts/git-commit
• http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html
• https://www.git-scm.com/book/en/v2/Distributed-Git-Contributing-to-a-Project#Commit-Guidelines
• Tim Perry's excellent git-confirm hook, which provided the inspiration and much of the scaffolding for this hook.