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Git Hook

git-msg can be installed as a prepare-commit-msg hook so that commit message generation happens automatically every time you run git commit.

Installing the hook

Per-repository (recommended)

Run inside a git repository:

git-msg hook install

This writes an executable script to .git/hooks/prepare-commit-msg.

Globally (all repositories)

Install once and have it apply to every git repo on your machine:

# First, configure a global hooks directory
git config --global core.hooksPath ~/.config/git/hooks
mkdir -p ~/.config/git/hooks

# Then install the hook globally
git-msg hook install --global

git-msg will read core.hooksPath from your git config and install there.

What the hook script looks like

#!/bin/sh
# Managed by git-msg. Do not edit manually.
# Skip generation when stdin is not an interactive terminal (e.g. CI,
# editor integrations, or any non-interactive shell environment).
if ! [ -t 0 ]; then
  exit 0
fi
exec git-msg generate --hook-mode --hook-msg-file "$1" --hook-source "${2:-}"

Key behaviours:

  • No TTY, no generation — the script checks whether stdin is an interactive terminal (-t 0). The review TUI requires an interactive stdin to read user input, so the hook exits silently when one is not available (CI pipelines, editor integrations, non-interactive shells).
  • Hook mode — git-msg writes the generated message to the commit message file that git passes as $1, instead of calling git commit -m itself.
  • Source-aware — the $2 argument from git tells git-msg what triggered the commit. Only normal and message sources trigger generation; merges, squashes, and amends are passed through unchanged.

How commit source dispatch works

prepare-commit-msg receives a second argument indicating why the commit is happening:

Source Example git-msg behaviour
(empty) git commit Generates message
message git commit -m "..." Generates message (overwrites)
merge Merge commit Passes through — no generation
squash Squash commit Passes through — no generation
template commit.template set Passes through — no generation
commit git commit --amend Passes through — no generation

Using the hook

Once installed, just run git commit as normal:

git add src/
git commit

The review TUI appears:

  Generated commit message:
  > Use as-is
    Edit inline
    Open $EDITOR
    Abort

feat(auth): add JWT refresh token rotation

Select an option. The chosen message is written to the commit and git proceeds normally.

Checking hook status

# Check if the local hook is installed
ls -la .git/hooks/prepare-commit-msg

# Check if a global hook is installed
git config --get core.hooksPath
ls -la "$(git config --get core.hooksPath)/prepare-commit-msg"

Reinstalling after updates

If you update git-msg and want to ensure the latest hook script is in place (e.g. after a bug fix to the script), reinstall:

git-msg hook install       # local
git-msg hook install --global  # global

Install is idempotent — running it again replaces the script silently.

Removing the hook

git-msg hook uninstall              # local
git-msg hook uninstall --global     # global

Uninstall is also idempotent — exits 0 if no hook is present.