git: latest changes grouped by day

lastDays.sh

#!/bin/bash
for i in $(seq 0 10)
do
    date=$(date --date="$i days ago" +%D)
    first=$(git log --format="%h" --after="$date 00:00" --before="$date 23:59" | tail -n1)
    last=$(git log --format="%h" --after="$date 00:00" --before="$date 23:59" | head -n1)
    if [ -n "$first" ] && [ -n "$last" ]; then
        diff=$(git diff --shortstat $first^..$last)
        echo "$(date --date=$date): $diff"
    else
        echo "$(date --date=$date):  no changes"
    fi
done