git nocheckin pre-commit hook

#!/bin/sh
# Prevent commit if diff contains "NOCHECKIN"

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

# Redirect output to stderr.
exec 1>&2

git diff --name-only $against | xargs grep -iH nocheckin
if [[ $? ]]; then
    exit 1
fi