如何防止shutil.move在文件已存在时覆盖该文件？

Question

我在 Windows 上使用这段 Python 代码：

shutil.move(documents_dir + "\\" + file_name, documents_dir + "\\backup\\"
            + subdir_name + "\\" + file_name)

当这段代码被调用多次时，它会覆盖目标文件。我想将文件移动，如果目标已经存在，则重命名它。

例如，file_name = foo.pdf，并且在backup文件夹中将出现foo.pdf，foo(1).pdf，foo(2).pdf等，或者类似地，例如使用破折号foo-1.pdf，foo-2.pdf等。

- xralf

Answer 1

在进行操作时，您可以随时检查os.path.exists()是否存在。

import os
import shutil

file_name = 'test.csv'
documents_dir = r'C:\BR\Test'
subdir_name = 'test'

# using os.path.join() makes your code easier to port to another OS
source = os.path.join(documents_dir, file_name)
dest = os.path.join(documents_dir, 'backup', subdir_name, file_name)

num = 0
# loop until we find a file that doesn't exist
while os.path.exists(dest):
    num += 1

    # use rfind to find your file extension if there is one
    period = file_name.rfind('.')
    # this ensures that it will work with files without extensions
    if period == -1:
        period = len(file_name)

    # create our new destination
    # we could extract the number and increment it
    # but this allows us to fill in the gaps if there are any
    # it has the added benefit of avoiding errors 
    # in file names like this "test(sometext).pdf"
    new_file = f'{file_name[:period]}({num}){file_name[period:]}'

    dest = os.path.join(documents_dir, 'backup', subdir_name, new_file)

shutil.move(source, dest)

或者，由于这可能在循环中使用，您可以将其放入函数中。

import os
import shutil

def get_next_file(file_name, dest_dir):
    dest = os.path.join(dest_dir, file_name)
    num = 0

    while os.path.exists(dest):
        num += 1

        period = file_name.rfind('.')
        if period == -1:
            period = len(file_name)

        new_file = f'{file_name[:period]}({num}){file_name[period:]}'

        dest = os.path.join(dest_dir, new_file)

    return dest

file_name = 'test.csv'
documents_dir = r'C:\BR\Test'
subdir_name = 'test'

source = os.path.join(documents_dir, file_name)

dest = get_next_file(file_name, os.path.join(documents_dir, 'backup', subdir_name))

shutil.move(source, dest)

- Axe319