pre-commit — Notification just prior to commit completion.
The pre-commit hook is run just before a commit transaction is promoted to a new revision. Typically, this hook is used to protect against commits that are disallowed due to content or location (for example, your site might require that all commits to a certain branch include a ticket number from the bug tracker, or that the incoming log message is non-empty).
If the pre-commit hook program returns a non-zero exit value, the commit is aborted, the commit transaction is removed, and anything printed to stderr is marshalled back to the client.
The command-line arguments passed to the hook program, in order, are:
commit transaction name