pre-commit hook to prevent me from accidentally checking in debug code

gistfile1.sh

#!/bin/sh
#
# This hook prevents you from committing any file containing the 
# words "do not commit".
#
# The idea is that I can add a comment to prevent myself from 
# committing a change related to debugging or hacking.
#
# To enable this hook, rename this file to ".git/hooks/pre-commit".

DIFF_FILES=`git diff-index HEAD --cached --name-only`

if [ $? -ne 0 ]
then
  echo "Error getting list of changed files in pre-commit hook"
  exit 4
fi

for FILE in ${DIFF_FILES}
do
  grep -rin -C2 "DO NOT COMMIT" "$FILE"

  if [ $? -ne 0 ]
  then
    false
  else
    echo "---------------------------"
    echo "Bad contents in file: $FILE"
    exit 4
  fi
done

exit 0