date="2020-01-01T01:00:00"
DRY_RUN=1
branches=

for branch in $(git branch -a | sed 's/^\s*//' | sed 's/^remotes\///' | grep -v 'master$'); do
  if [[ "$(git log --since=$date $branch | wc -l)" -eq 0 ]]; then
    if [[ "$branch" =~ "origin/" ]]; then
      if [[ -z $branches ]]; then
        branches=$(echo "$branch" | sed 's/^origin\///')
      else
        branches="$branches "$(echo "$branch" | sed 's/^origin\///')
      fi
    fi
  fi
done
if [[ ! -z $branches ]]; then
  if [[ "$DRY_RUN" -eq 1 ]]; then
    echo git branch -D $branches
    echo git push --delete origin $branches
  else
    git branch -D $branches
    git push --delete origin $branches

    # clean up locally
    git remote prune origin
  fi
fi
Echo "End"