Rsync 没有删除文件并抱怨“设备上没有剩余空间 (28)”

由于缺乏一个简洁的解决方案，我用 Python 编写了一个 hack 来遍历目标并删除源中不存在的文件和目录。

确保您不会意外交换源和目标，否则您将丢失原始文件。顺序同rsync：先源后目标。

默认情况下，代码会在删除前五个路径之前提示确认，因此您可以验证您没有删除源。它删除目标中作为源中符号链接的文件。

用于：

python3 rsync_pre_process.py /Volumes/source /Volumes/target

然后您可以运行rsync，例如如下（并-a保留符号链接）：

rsync -avxW --delete --delete-before --progress /Volumes/source /Volumes/target

这是代码rsync_pre_process.py：

#!/usr/bin/env python3
# 
# Usage: python3 rsync_pre_process.py /Volumes/source /Volumes/target [5]
#
# You can then run: rsync -avxW --delete --delete-before --progress /Volumes/source /Volumes/target
# 
# This code deletes files present in the target that are missing from the
# source. It circumvents one case of rsync's error "No space left on device
# (28)" even though you may run rsync with `-delete` and `--delete-before`.
#
# It prompts for confirmation to delete a certain number of files or
# directories, 5 by default, before deleting files without confirmation.
#
# It removes files in the target that are symlinks in the source.
#
# author: Miguel Morin
# copyright: public domain
# year: 2019

import os
import pathlib
import shutil
import sys

MAX_VERIFICATIONS = 5

def remove(path, verify):
    """Removes a file or directory, asking for confirmation first if requested."""
    if verify:
        print(path)
        print("Remove this file? Press RET to proceed, C-c to abort.")
        sys.stdin.read(1)
    p = pathlib.Path(path)
    if os.path.islink(path) or not p.is_dir():
        os.remove(path)
    else:
        try:
            # shutil.rmtree instead of os.remove() because the former works in
            # iMovie folders where the latter throws an error, `PermissionError:
            # [Errno 1] Operation not permitted:`
            shutil.rmtree(path)
        except PermissionError as e:
            print("Unable to remove '%s' due to permission error" % path)

def cleanup(source, target, max_verifications):
    """Deletes all files from the target that are missing from the source, prompting 
    confirmations up to `max_verifications`.
    """
    num_verifications = 0
    for root, dirs, files in os.walk(target, topdown = False):
        for name in files + dirs:
            verify = num_verifications < max_verifications
            target_filepath = os.path.join(root, name)
            source_filepath = target_filepath.replace(target, source)
            if not os.path.exists(source_filepath) or os.path.islink(source_filepath):
                remove(target_filepath, verify)
                num_verifications += 1

def main():
    source = sys.argv[1]
    target = sys.argv[2]

    if not (source and target):
        raise ValueError("You must supply source and target arguments. Your arguments: " + str(argv[1:]))

    if 4 == len(sys.argv):
        max_verifications = int(sys.argv[3])
    else:
        max_verifications = MAX_VERIFICATIONS

    cleanup(source = source, target = target, max_verifications = max_verifications)

if "__main__" == __name__:
    main()