[Python-Dev] os.walk() silently ignores errors (original) (raw)

Harri Pasanen harri.pasanen@trema.com
Tue, 13 May 2003 17:06:27 +0200

On Tuesday 13 May 2003 15:51, Guido van Rossum wrote:

> I've just noticed that os.walk() silently skips unreadable > directories. I think this is surprising behaviour, which at > least should be documented (there is a comment explaining this is > source, but nothing in the doc string). Is it too late to add an > optional callback argument to handle unreadable directories, so > the caller could log them, raise an exception or whatever? I > think the default behaviour should still be to silently ignore > them, but it would be nice to have a way to override it.

Ignoring is definitely the right thing to do by default, as otherwise the existence of a single unreadable directory would cause your entire walk to fail. What's your use case for wanting to do something else?

Sometimes I'm looking for something in a files in directory tree, forgetting I don't have access permissions to a particular subdirectory by default. So the search can silently fail, and I'm left with the wrong idea that what I was looking is not there.

Ideally, I'd like the possibility have my script remind me to login as root prior to running it.

I know I could do some defensive programming in the walker function to go around this, but I this would likely imply more stat calls and impact performance.

I've been bitten by this a couple of times, so I thought I'd pipe in.

-Harri