git-multi-repo-statistics

script.sh

#!/bin/sh

# shellcheck disable=SC2044
for repo in $(find . -mindepth 1 -maxdepth 1 -type d); do
    if [ ! -d "$repo/.git" ]; then
        continue
    fi
    (
        git -C "$repo" shortlog --group=':%aE' -s
    ) | cat
done |
    sort -k 2,2 |
    awk -F ':' '{contributors[$2]+=$1} END { for (contributor in contributors) { printf("%s\t%s\n", contributors[contributor], contributor) }}' |
    sort -n -r -k1,1