Python:"OSError:[Errno 2]没有此类文件或目录:" ...找到的文件? [英] Python: "OSError: [Errno 2] No such file or directory:"... with the file it found?

问题描述

我正在编写一个Python脚本，其部分功能是查找特定种类的最后修改文件.就我而言，它是用于Mac OS X上最后修改的屏幕保护程序plist文件.下面是处理此问题的一些代码:

I'm writing a Python script where part of its function is to find the last modified file of a specific kind. In my case, it's for the last modified screen saver plist file on Mac OS X. Below are the bits of code which deal with this:

import os

PlistFolder = "Library/Preferences/ByHost"
MacPlistPath = os.path.join(HomeFolder, PlistFolder)
PlistSSMac = max([f for f in os.listdir(MacPlistPath) if f.lower().endswith('.plist') and f.lower().startswith('com.apple.screensaver.')], key=os.path.getmtime)

但是，当我运行它时，它在返回所需的确切信息时给了我一个错误...

When I run it, however, it gives me an error while returning exactly what I wanted it to find...

Traceback (most recent call last):
  File "tcn_test.py", line 29, in <module>
    MacPlistFile = max([f for f in os.listdir(MacPlistPath) if f.lower().endswith('.plist') and f.lower().startswith('com.apple.screensave
r.')], key=os.path.getmtime)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/genericpath.py", line 62, in getmtime
    return os.stat(filename).st_mtime
OSError: [Errno 2] No such file or directory: 'com.apple.screensaver.097EBF05-D7B5-5FD6-A031-12734A82135D.plist'

关于导致此问题的原因以及如何解决的任何想法?

Any ideas on what causes this and how I can fix it?

提前谢谢！

推荐答案

listdir不会在目录名前添加，因此您不能原样传递os.path.getmtime.

listdir won't prepend the directory name, so you cannot pass os.path.getmtime as-is.

用lambda包裹起来，并与源目录连接:

Wrap it with a lambda and join with the source directory:

MacPlistFile = max((f for f in os.listdir(MacPlistPath) if f.lower().endswith('.plist') and f.lower().startswith('com.apple.screensaver.')), key=lambda f : os.path.getmtime(os.path.join(MacPlistPath,f)))

但是，从更大的角度来看，使用glob.glob和通配符会更好:

But looking at the bigger picture, you'd be even better off with glob.glob and a wildcard:

import glob
MacPlistFile = os.path.basename(max(glob.glob(os.path.join(MacPlistPath,"com.apple.screensaver.*.plist")), key=os.path.getmtime))

glob.glob返回完整路径，因此现在您可以直接将os.path.getmtime用作键.您只需要在最后执行os.path.basename即可仅获取最后修改的文件名.

glob.glob returns the full path, so now you can use os.path.getmtime directly as a key. You just have to perform an os.path.basename in the end to get only the last modified file name.

此外:无需创建列表理解. 生成器理解足以使max有效地工作.

Aside: no need to create a list comprehension. A generator comprehension is enough for max to work efficiently.

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