How do I control the automated commit message on a merge?

I am using git-svn. The SVN repository I'm dealing with has a standard comment convention I must follow. It is a simple static string of information that must appear on the first line of the commit message. Everything else can be free-form.

I figured out how to add a commit template to my gitconfig file. So for regular commits, I think I'm fine. But when Git does a merge (no conflicts), it auto-generates a commit message like:

        Merge branch 'master' of  /path/to/other/repo

How can I change this so my required string gets written at the beginning of the commit message. I played with the commit-msg and prepare-commit-msg hooks, but it didn't seem to get triggered in the merge case.

Also, having the prepare-commit-msg hook add text had the side-effect that in my normal commits, the message was always accepted, even when I wanted to abort (vi using :q!). In case I ever do need to use prepare-commit-msg, is there a way I can use it where abort still can work?

Thank you

Hi,

On Tue, 3 Jun 2008, Marvin Fraeman wrote:

s/./?/

You might be happy with a post-merge hook amending the commit with a completely different message.

Hth, Dscho

On Tue, Jun 3, 2008 at 3:51 PM, Johannes Schindelin <Johannes.Schindelin@gmx.de> wrote:

Where do I do the substitution in this case? I don't know where this default commit message is coming from and where to intercept it. Are you saying this is part of the post-merge hook or is that an alternative solution?

Thank you

Hi,

In the question that you sent to the list ;-) (But something like s/\./?/ makes more sense.)

The real answer of Johannes to your question was only:

Meaning, you should put something like
 #!/bin/sh
 git commit -m "This is my new commit message." --amend
or better:
 #!/bin/sh
 git commit --amend -m "$(git cat-file commit HEAD |
 	sed -e '1,/^$/d;s/^/YOUR SIMPLE STATIC STRING HERE\n\n/')"
into .git/hooks/post-merge (and make it executable).
YOUR SIMPLE STATIC STRING HERE is the new first line.
Replace the \n\n by a space to get someting like
"YOUR SIMPLE STATIC STRING HERE Merge foo into HEAD."

Let the commit-msg hook add the text afterwards.

Or remove the prepared commit message in vi and then press :x (or :wq), because commit aborts on an *empty* commit message and not on an unchanged commit message.

Regards,
  Stephan