Add commit hook and make the verification customizable.

There are three hooks:

    - 'pre-commit' is given an opportunity to inspect what is
      being committed, before we invoke the EDITOR for the
      commit message;

    - 'commit-msg' is invoked on the commit log message after
      the user prepares it;

    - 'post-commit' is run after a successful commit is made.

The first two can interfere to stop the commit.  The last one is
for after-the-fact notification.

The earlier built-in commit checker is now moved to pre-commit.

Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 14 insertions, 0 deletions

diff --git a/templates/hooks--commit-msg b/templates/hooks--commit-msg
new file mode 100644
index 000000000..029f897c4
--- /dev/null
+++ b/templates/hooks--commit-msg
@@ -0,0 +1,14 @@
+#!/bin/sh
+#
+# An example hook script to check the commit log message.
+# Called by git-commit-script with one argument, the name of the file
+# that has the commit message.  The hook should exit with non-zero
+# status after issuing an appropriate message if it wants to stop the
+# commit.  The hook is allowed to edit the commit message file.
+#
+# To enable this hook, make this file executable.
+
+# This example catches duplicate Signed-off-by lines.
+
+test "" = "$(grep '^Signed-off-by: ' "$1" |
+	 sort | uniq -c | sed -e '/^[ 	]*1 /d')"