Git pre-commit hook to limit number of changes

line_count.zsh

#!bin/zsh
maxlines=100
lines=0
# read shortened commit data
git diff --cached --oneline --numstat | while read commit; do
  # use tr to break words into newlines
  echo $commit | tr -s '[[:space:]]' '\n' | while read word; do
    # match numbers only
    if [[ $word =~ ^[0-9]+$ ]]
    then
      # add number of changes to total lines changed
      ((lines=$lines+$word))
    fi
  done
done

echo $lines' lines changed.'
if [[ $lines -le $maxlines ]]
then
  exit 0
else
  echo 'Too many changes are included. the max is '$maxlines
  exit 1
fi