Git pre-commit script to run all the modified files through php-lint. Won't let you commit php file with a syntax error.

pre-commit.lint

#!/bin/sh
#
# Hook script to check the changed files with php lint
# Called by "git commit" with no arguments.
#
# To enable this hook, rename this file to "pre-commit".

if git rev-parse --verify HEAD >/dev/null 2>&1
then
    against=HEAD
else
    # Initial commit: diff against an empty tree object
    against=4b825dc642cb6eb9a060e54bf8d69288fbee4904
fi

if !(git diff --cached --name-only --diff-filter=AM $against | grep 'php' | xargs -P 10 -n1 php -l)
then
    echo
    echo "Error: You attempted to commit one or more php files with syntax errors."
    echo
    echo "Please fix them and retry the commit."
    echo
    exit 1
fi

exec git diff-index --check --cached $against --

maybe use against=$(git rev-list --max-parents=0 HEAD) for initial commit instead of 4b825dc642cb6eb9a060e54bf8d69288fbee4904