#!/bin/bash

# use newline as separator
IFS=$'\n'

for author in $(git log --all --format='%cN' | sort -u); do
    echo $author; 
    git log --all --author="$author" --pretty=tformat: --numstat | awk '{ add += $1; subs += $2; loc += $1 - $2 } END { printf "++ %s\n-- %s\n= %s\n", add, subs, loc }' -
done

# git config --global alias.impact '!sh git-impact.sh'