Lib/os.py

cpython 3.14 @ ab2d84fe1023/Lib/os.py ↗

Lib/os.py is the Python layer of the os module. It imports from posix/nt (the C extension) and adds pure-Python utilities: _Environ, os.path, os.walk, os.makedirs, os.fspath, and various wrappers.

Map

Lines	Symbol	Role
1-100	Imports, name, path selection	Import posix or nt; select posixpath or ntpath
101-300	_Environ	MutableMapping backed by putenv/unsetenv
301-550	os.walk	Depth-first directory tree generator
551-700	os.makedirs, os.removedirs, os.renames	Recursive directory operations
701-900	os.fspath, os.fsencode, os.fsdecode	Filesystem path protocol
901-1150	os.replace, os.link, os.symlink, os.scandir wrappers	Thin Python wrappers

Reading

_Environ

_Environ subclasses MutableMapping. __setitem__ calls putenv(key, value); __delitem__ calls unsetenv(key). The underlying dict is populated from environ at module import time.

# CPython: Lib/os.py:680 _Environ.__setitem__
def __setitem__(self, key, value):
    ...
    self.putenv(key, value)
    self._data[key] = value

os.walk

os.walk(top, topdown=True, onerror=None, followlinks=False) yields (dirpath, dirnames, filenames) tuples. With topdown=True, the caller can prune dirnames in-place to control recursion.

# CPython: Lib/os.py:417 walk
def walk(top, topdown=True, onerror=None, followlinks=False):
    sys.audit("os.walk", top, topdown, onerror, followlinks)
    return _walk(fspath(top), topdown, onerror, followlinks)

os.fspath

os.fspath(path) returns path unchanged if it is a str or bytes, or calls path.__fspath__() if it defines one (as pathlib.Path does). This is the PEP 519 path-like object protocol.

os.makedirs

os.makedirs(path, mode=0o777, exist_ok=False) creates intermediate directories recursively. With exist_ok=True it suppresses FileExistsError for the leaf directory.

gopy notes

Not yet ported. module/os/ will wrap Go's os package. _Environ can use Go's os.Getenv/os.Setenv/os.Unsetenv. os.walk maps to a recursive os.ReadDir loop. os.fspath is a protocol check that the gopy type system will handle via __fspath__.