io.md

Python File and Network I/O

Also see Python Filesystem and Path Libraries.

File I/O

Files are opened with the built-in function open().

• open(file): file may be a path-like object or a file descriptor. Returns a file object: TextIOWrapper, BufferedIOBase subclass or unbuffered FileIO.
  • mode='r': r read (default), w write, a append, + 'rw', w+b truncates (but not r+b), b binary, t text (default), x exclusive.
  • buffering=-1: 0=none, 1=line, ≥2=block. Default -1 is lines for text, system-chosen blocksize for binary.
  • encoding=None: Text mode only, default is platform-dependent. See codecs.
  • errors=None: Handles codec errors.
  • newline=None: Used only for deprecated mode='u' universal newlines.
  • closefd=True: Close file arg if a file descriptor.
  • opener=None: A callable, default os.open.

Network I/O

The socket module is the standard BSD API. A buffered file object wrapping a socket can be obtained with socket.makefile().

• socket.makefile(): Args similar to open().
  • mode: Only r, w, b allowed.
  • Socket must be blocking.
  • close() does not close underlying socket.
  • Windows cannot mix the returned object with file-like objects.

Warnings:

• sock.shutdown(socket.SHUT_WR) on a Unix domain stream socket will shut down both directions (Ubuntu 18.04).