ZSH script that will group files into git commits by modified date. Useful for older repos.

commit_by_date.sh

#!/bin/zsh
format_date() {
  date -r $1 +"%Y-%m-%dT%H:%M:%S"
}
declare -A files_by_date
git ls-files --modified --others --exclude-standard | while read file
do
    timestamp=$(stat -f "%m" "$file")
    date=$(format_date $timestamp)
    files_by_date[$date]+="$file "
done

for date in "${(k)files_by_date[@]}"; do
    echo $date "$files_by_date[$date]"
    echo "$files_by_date[$date]" | xargs git add
    GIT_AUTHOR_DATE="$date" GIT_COMMITTER_DATE="$date" git commit -m "Updated"
done