阅读并覆盖Python中的文件 [英] Read and overwrite a file in Python

问题描述

目前我使用的是：

f = open(filename, 'r+')
text = f.read()
text = re.sub('foobar', 'bar', text)
f.seek(0)
f.write(text)
f.close()

但问题是旧文件大于新文件。所以我最终得到一个新文件，其中有一部分旧文件。

But the problem is that the old file is larger than the new file. So I end up with a new file that has a part of the old file on the end of it.

推荐答案

如果你不想关闭并重新打开该文件，以避免竞争条件，您可以 truncate 它：

If you don't want to close and reopen the file, to avoid race conditions, you could truncate it:

f = open(filename, 'r+')
text = f.read()
text = re.sub('foobar', 'bar', text)
f.seek(0)
f.write(text)
f.truncate()
f.close()

功能也可能是更清洁和更安全的，使用打开为每mVChr的注释，即使发生错误也将关闭处理程序。

The functionality may also be cleaner and safer using with open as per mVChr's comment, which is will close the handler, even if an error occurs.

with open(filename, 'r+') as f:
    text = f.read()
    text = re.sub('foobar', 'bar', text)
    f.seek(0)
    f.write(text)
    f.truncate()

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