emulating du with os.walk

[Gerrit]

"Martin v. Löwis" wrote:
> Kirk Job-Sluder wrote:
> >There should be an easy way to get around this, or perhaps I'm better
> >off just parsing the output of du.
> 
> I suggest that you don't use os.path.walk, but write a recursive
> function yourself. You should find that the entire problem can
> be solved in 12 lines of Python code.

There are some nasty little problems which make it difficult.

First, what do you do with hardlinks? Suppose directory a/a, a/b and a/c
all contain the same 100 MiB file. Directory a/ only has 100 MiB, but a
naive script will report 300 MiB.

Most of the time, you'll want to stay in one filesystem.

You don't want to get stuck in recursive symlinks. If a/b is a symlink
to a/, you quickly get into an infinite loop.

Directories have a size too.

What do we do with files we can't read?

In /proc, even stranger subtleties exist which I don't understand -
ENOENT although listed by listdir() and that sort of thing.

Together with more options, human-readable file sizes and documentation,
it took be ~200 LOC at
http://topjaklont.student.utwente.nl/creaties/dkus.py

Note that du doesn't solve these problems either.

yours,
Gerrit.

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