Git Hooks

Hooks are little scripts you can place in $GIT_DIR/hooks directory

refs: githooks, Pro Git: Git Hooks


Ref: gitdoc: prepare_commit_msg

This hook is invoked by git commit after preparing the default message, and before the editor is started. It takes one to three parameters.

  • The name of the file that contains the prepared message.
  • The second is message if a -m or -F option was given, template with a -t option or configuration commit.template, commit if a -c, -C or --amend option was given, merge for a merge commit or with a .git/MERGE_MSG file; and squash if a .git/SQUASH_MSG file exists.
  • The third is only for a commit and is the commit SHA-1.

A non-zero exit means a failure of the hook and aborts the commit.

format="# %h %s [%an]"
log="$(git log --pretty="${format}" -${num_messages})"
# last ${num_messages} messages
# ----------------------"
template() {
    echo "${header}"
    echo "${log}"
case "$2" in
merge|template|squash) ;;
""|commit) template >> $1;;
*)  echo "error in prepare-commit-msg hook" >&2
    exit 1