Function open

Lib/_pyio.py:75–271

r"""Open file and return a stream. Raise OSError upon failure. file is either a text or byte string giving the name (and the path if the file isn't in the current working directory) of the file to be opened or an integer file descriptor of the file to be wrapped. (If a file descrip

(file, mode="r", buffering=-1, encoding=None, errors=None,
         newline=None, closefd=True, opener=None)

# See init_set_builtins_open() in Python/pylifecycle.c.
@staticmethod
def open(file, mode="r", buffering=-1, encoding=None, errors=None,
         newline=None, closefd=True, opener=None):

    r"""Open file and return a stream.  Raise OSError upon failure.

    file is either a text or byte string giving the name (and the path
    if the file isn't in the current working directory) of the file to
    be opened or an integer file descriptor of the file to be
    wrapped. (If a file descriptor is given, it is closed when the
    returned I/O object is closed, unless closefd is set to False.)

    mode is an optional string that specifies the mode in which the file is
    opened. It defaults to 'r' which means open for reading in text mode. Other
    common values are 'w' for writing (truncating the file if it already
    exists), 'x' for exclusive creation of a new file, and 'a' for appending
    (which on some Unix systems, means that all writes append to the end of the
    file regardless of the current seek position). In text mode, if encoding is
    not specified the encoding used is platform dependent. (For reading and
    writing raw bytes use binary mode and leave encoding unspecified.) The
    available modes are:

    ========= ===============================================================
    Character Meaning
    --------- ---------------------------------------------------------------
    'r'       open for reading (default)
    'w'       open for writing, truncating the file first
    'x'       create a new file and open it for writing
    'a'       open for writing, appending to the end of the file if it exists
    'b'       binary mode
    't'       text mode (default)
    '+'       open a disk file for updating (reading and writing)
    ========= ===============================================================

    The default mode is 'rt' (open for reading text). For binary random
    access, the mode 'w+b' opens and truncates the file to 0 bytes, while
    'r+b' opens the file without truncation. The 'x' mode implies 'w' and
    raises an `FileExistsError` if the file already exists.

    Python distinguishes between files opened in binary and text modes,
    even when the underlying operating system doesn't. Files opened in
    binary mode (appending 'b' to the mode argument) return contents as
    bytes objects without any decoding. In text mode (the default, or when
    't' is appended to the mode argument), the contents of the file are
    returned as strings, the bytes having been first decoded using a
    platform-dependent encoding or using the specified encoding if given.

    buffering is an optional integer used to set the buffering policy.
    Pass 0 to switch buffering off (only allowed in binary mode), 1 to select
    line buffering (only usable in text mode), and an integer > 1 to indicate
    the size of a fixed-size chunk buffer.  When no buffering argument is
    given, the default buffering policy works as follows:

   * Binary files are buffered in fixed-size chunks; the size of the buffer
     is max(min(blocksize, 8 MiB), DEFAULT_BUFFER_SIZE)
     when the device block size is available.
     On most systems, the buffer will typically be 128 kilobytes long.

    * "Interactive" text files (files for which isatty() returns True)