Re: Arguments to git hooks

From: Andrew Sayers <andrew-git@pileofstuff.org>
Date: May 7, 2012, 22:17 UTC
Message-ID: <4FA84A0F.6060608@pileofstuff.org>
In-Reply-To: <CAH-tXsB4PBS_YjW4DCjT6ORmNPomQ8XMPbKx3hxVNH=FyB2u3g@mail.gmail.com>

On 06/05/12 19:35, jaseem abid wrote:

Show 9 quoted lines

> Hello all,
> 
> I am trying to write a hook '.git/hooks/commit-msg' to be run before
> every commit.
> 
> How can I pass arguments to the script? Now by default the only arg I
> am getting is `.git/COMMIT_EDITMSG'`. I would love to get the list of
> files I tried to commit also into the script so that I can run a lint
> program on it before committing it. How can I get this done?

First, a standard warning - consider using a pre-receive hook instead of a pre-commit hook. A lot of git's power comes from making commits as cheap as possible, so rules like "no committing until your code is pretty" tend to stifle people. For example, I often commit changes before running lint-type operations, then use `git add -p` and `git checkout -p` to selectively accept/reject individual changes. When I'm done, I `git commit --amend` to pretend the original commit never happened. A pre-receive hook gives you most of the same guarantees as a pre-commit hook with almost none of the cost.

Having said that, there are situations where pre-commit hooks are a good idea (like catching "DO NOT COMMIT" comments). I've played with this a little before, and never found a very satisfactory solution. Here are some important cases:

# git status will sometimes tell you the file that will be committed: # edit foo git add foo git commit

# git status will sometimes need a bit of careful parsing: # edit foo # edit bar git add foo git commit

# git status sometimes tells you the right file but the wrong contents: # edit foo git add foo # edit foo again git commit

# but often git status will tell you the wrong file altogether: # edit foo # edit bar git add foo git commit bar

The best solution I've found is a `git commit` wrapper that does something like `CHANGES="$(git commit $@ --dry-run -v)"` to get a reliable diff, then starts work from there.

	- Andrew