Directory tree generator.
This behaves exactly like walk(), except that it yields a 4-tuple
dirpath, dirnames, filenames, dirfd
`dirpath`, `dirnames` and `filenames` are identical to walk() output,
and `dirfd` is a file descriptor referring to the directory `dirpath`.
The advantage of fwalk() over walk() is that it's safe against symlink
races (when follow_symlinks is False).
If dir_fd is not None, it should be a file descriptor open to
a directory, and top should be relative; top will then be relative to
that directory. (dir_fd is always supported for fwalk.)
Caution:
Since fwalk() yields file descriptors, those are only valid until the
next iteration step, so you should dup() them if you want to keep them
for a longer period.
Example:
import os
for root, dirs, files, rootfd in os.fwalk('python/Lib/xml'):
print(root, "consumes", end="")
print(sum(os.stat(name, dir_fd=rootfd).st_size for name in files),
end="")
print("bytes in", len(files), "non-directory files")
if '__pycache__' in dirs:
dirs.remove('__pycache__') # don't visit __pycache__ directories