Documentation/cmd-hook-commit-msg.txt - gerrit - Git at Google Sign in gerrit / gerrit / refs/tags/v2.5-rc0 / . / Documentation / cmd-hook-commit-msg.txt blob: bd602c11cf451d6846930d9f7d490f7e582c2952 [file] [log] [blame] commit-msg Hook =============== NAME ---- commit-msg - Edit commit messages to insert a `Change-Id` tag. DESCRIPTION ----------- A Git hook automatically invoked by `git commit`, and most other commit creation tools such as `git citool` or `git gui`. The Gerrit Code Review supplied implementation of this hook is a short shell script which automatically inserts a globally unique Change-Id tag in the footer of a commit message. When present, Gerrit uses this tag to track commits across cherry-picks and rebases. After the hook has been installed in the user's local Git repository for a project, the hook will modify a commit message such as: ---- Improve foo widget by attaching a bar. We want a bar, because it improves the foo by providing more wizbangery to the dowhatimeanery. Signed-off-by: A. U. Thor <author@example.com> ---- by inserting a new `Change-Id: ` line in the footer: ---- Improve foo widget by attaching a bar. We want a bar, because it improves the foo by providing more wizbangery to the dowhatimeanery. Change-Id: Ic8aaa0728a43936cd4c6e1ed590e01ba8f0fbf5b Signed-off-by: A. U. Thor <author@example.com> ---- The hook implementation is reasonably intelligent at inserting the Change-Id line before any Signed-off-by or Acked-by lines placed at the end of the commit message by the author, but if no such lines are present then it will just insert a blank line, and add the Change-Id at the bottom of the message. If a Change-Id line is already present in the message footer, the script will do nothing, leaving the existing Change-Id unmodified. This permits amending an existing commit, or allows the user to insert the Change-Id manually after copying it from an existing change viewed on the web. OBTAINING --------- To obtain the 'commit-msg' script use scp, wget or curl to download it to your local system from your Gerrit server. You can use either of the below commands: ==== $ scp -p -P 29418 <your username>@<your Gerrit review server>:hooks/commit-msg <local path to your git>/.git/hooks/ $ curl -o <local path to your git>/.git/hooks/commit-msg <your Gerrit http URL>/tools/hooks/commit-msg ==== A specific example of this might look something like this: .Example ==== $ scp -p -P 29418 john.doe@review.example.com:hooks/commit-msg ~/duhproject/.git/hooks/ $ curl -o ~/duhproject/.git/hooks/commit-msg http://review.example.com/tools/hooks/commit-msg ==== Make sure the hook file is executable: ==== $ chmod u+x ~/duhproject/.git/hooks/commit-msg ==== SEE ALSO -------- * link:user-changeid.html[Change-Id Lines] * link:http://www.kernel.org/pub/software/scm/git/docs/git-commit.html[git-commit(1)] * link:http://www.kernel.org/pub/software/scm/git/docs/githooks.html[githooks(5)] IMPLEMENTATION -------------- The hook generates unique Change-Id lines by creating a virtual commit object within the local Git repository, and obtaining the SHA-1 hash from it. Like any other Git commit, the following properties are included in the computation: * SHA-1 of the tree being committed * SHA-1 of the parent commit * Name, email address, timestamp of the author * Name, email address, timestamp of the committer * Proposed commit message (before Change-Id was inserted) Because the names of the tree and parent commit, as well as the committer timestamp are included in the hash computation, the output Change-Id is sufficiently unique. GERRIT ------ Part of link:index.html[Gerrit Code Review] Powered by Gitiles| Privacytxt json