Name a specific client-side Git hook that can be used to automatically check commit message format *beforea commit is finalized.

The specific client-side Git hook that can be used to automatically check commit message format before a commit is finalized is the `commit-msg` hook. A Git hook is an executable script that Git runs automatically at specific points during its operations, allowing for custom automation and policy enforcement. Client-side hooks, like `commit-msg`, execute on an individual developer's local machine, meaning they apply only to that specific repository clone. The `commit-msg` hook is triggered after a developer has finished writing their commit message in the editor, but critically, *beforeGit creates the actual commit object and records it in the repository. When this hook runs, Git passes the full path to a temporary file containing the commit message as the first argument to the `commit-msg` script. The script then reads the content of this temporary file. It can apply predefined rules to validate the commit message format, which refers to the structured way a commit message is written, such as a maximum length for the subject line, the presence of an empty line separating the subject from the body, or adherence to conventional commit standards. For example, a script might check if the first line (subject) is shorter than 50 characters. If the `commit-msg` script finds that the message does not conform to the required format, it must exit with a non-zero status code. When Git detects a non-zero exit status from a hook, it interprets this as a failure and aborts the entire commit process, preventing the non-conforming commit from being finalized and saved into the repository. If the message passes all checks, the script exits with a zero status code, allowing Git to proceed with finalizing the commit. This mechanism ensures that all commits made in a repository adhere to desired messaging standards, improving the clarity and maintainability of the project's history.