> From: eryk...@gmail.com > Date: Sat, 23 Apr 2016 15:22:35 -0500 > Subject: Re: Remove directory tree without following symlinks > To: python-list@python.org > > On Sat, Apr 23, 2016 at 4:34 AM, Albert-Jan Roskam > wrote: >> >>> From: eryk...@gmail.com >>> Date: Fri, 22 Apr 2016 13:28:01 -0500 >>> On Fri, Apr 22, 2016 at 12:39 PM, Albert-Jan Roskam >>> wrote: >>>> FYI, Just today I found out that shutil.rmtree raises a WindowsError if >>>> the dir is read-only (or its contents). Using 'ignore_errors', won't help. >>>> Sure, no error is raised, but the dir is not deleted either! A 'force' >>>> option >>>> would be a nice improvement. >>> >>> Use the onerror handler to call os.chmod(path, stat.S_IWRITE). For >>> example, see pip's rmtree_errorhandler: >>> >>> https://github.com/pypa/pip/blob/8.1.1/pip/utils/__init__.py#L105 >> >> Thanks, that looks useful indeed. I thought about os.chmod, but with >> os.walk. That seemed expensive. So I used subprocess.call('rmdir "%s" /s /q' >> % dirname). That's Windows only, of course, but aside of that, is using >> subprocess less preferable? > > I assume you used shell=True in the above call, and not an external > rmdir.exe. There are security concerns with using the shell if you're > not in complete control of the command line. > > As to performance, cmd's rmdir wins without question, not only because > it's implemented in C, but also because it uses the stat data from the > WIN32_FIND_DATA returned by FindFirstFile/FindNextFile to check for > FILE_ATTRIBUTE_DIRECTORY and FILE_ATTRIBUTE_READONLY. > > On the other hand, Python wins when it comes to working with deeply > nested directories. Paths in cmd are limited to MAX_PATH characters. > rmdir uses DOS 8.3 short names (i.e. cAlternateFileName in > WIN32_FIND_DATA), but that could still exceed MAX_PATH for a deeply > nested tree, or the volume may not even have 8.3 DOS filenames. > shutil.rmtree allows you to work around the DOS limit by prefixing the > path with "\\?\". For example: > > >>> subprocess.call(r'rmdir /q/s Z:\Temp\long', shell=True) > The path Z:\Temp\long\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa > aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa > aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa > aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa > aaaaa is too long. > 0 > > >>> shutil.rmtree(r'\\?\Z:\Temp\long') > >>> os.path.exists(r'Z:\Temp\long') > False > > Using "\\?\" requires a path that's fully qualified, normalized > (backslash only), and unicode (i.e. decode a Python 2 str).
Aww, I kinda forgot about that already, but I came across this last year [1]. Apparently, shutil.rmtree(very_long_path) failed under Win 7, even with the "silly prefix". I believe very_long_path was a Python2-str. It seems useful if shutil or os.path would automatically prefix paths with "\\?\". It is rarely really needed, though. (in my case it was needed to copy a bunch of MS Outlook .msg files, which automatically get the subject line as the filename, and perhaps the first sentence of the mail of the mail has no subject). [1] https://mail.python.org/pipermail/python-list/2015-June/693156.html -- https://mail.python.org/mailman/listinfo/python-list
