rsync sometimes delete files with no backup, so this script is a solution to safely sync things

safe_backup.py

import filecmp
import os
import pathlib
import shutil


def no_change(src_file, dest_file):
    equal = filecmp.cmp(src_file.resolve(), dest_file.resolve(), False)
    return equal


def remove_file(dest_file):
    return os.unlink(str(dest_file))


def copy_file(src_file, dest_file):
    if not os.path.exists(dest_file.parent):
        os.makedirs(dest_file.parent, exist_ok=True)
    print('copyfile:', src_file, dest_file)
    shutil.copyfile(src_file, dest_file, follow_symlinks=True)


def safe_backup(from_dir, to_dir, backup_dir):
    src_path = pathlib.Path(from_dir)
    dest_path = pathlib.Path(to_dir)
    backup_path = pathlib.Path(backup_dir)
    src_files = src_path.glob('**/*')
    dest_files = dest_path.glob('**/*')

    # 备份已删除文件
    for dest_file in dest_files:
        if dest_file.is_dir():
            continue
        relative_path = dest_file.relative_to(dest_path)
        src_file = src_path / relative_path
        backup_file = backup_path / relative_path
        if not src_file.exists():
            copy_file(dest_file, backup_file)
            remove_file(dest_file)

    # 备份修改的文件, 跳过新增的文件
    for src_file in src_files:
        if src_file.is_dir():
            continue
        relative_path = src_file.relative_to(src_path)
        dest_file = dest_path / relative_path
        if not dest_file.exists():
            copy_file(src_file, dest_file)
        else:
            if not no_change(src_file, dest_file):
                backup_file = backup_path / relative_path
                copy_file(dest_file, backup_file)
                copy_file(src_file, dest_file)

    # 删除无用的文件夹
    dest_files = dest_path.glob('**/*')
    for dest_file in dest_files:
        if dest_file.is_dir():
            relative_path = dest_file.relative_to(dest_path)
            src_file = src_path / relative_path
            if not src_file.exists():
                shutil.rmtree(dest_file)


def main():
    from argparse import ArgumentParser
    parser = ArgumentParser()
    parser.add_argument('--src_dir')
    parser.add_argument('--dest_dir')
    parser.add_argument('--back_dir')
    args = parser.parse_args()
    safe_backup(args.src_dir, args.dest_dir, args.back_dir)


if __name__ == '__main__':
    main()