6.1.3 File Descriptor Operations
These functions operate on I/O streams referred to using file descriptors.
-
- Close file descriptor fd. Availability: Macintosh, Unix, Windows.
Note: this function is intended for low-level I/O and must be applied to a file
descriptor as returned by open() or pipe().
To close a ``file object'' returned by the built-in function open()
or by popen() or fdopen(), use its close() method.
-
- Return a duplicate of file descriptor fd. Availability: Macintosh, Unix, Windows.
-
- Duplicate file descriptor fd to fd2, closing the latter first if
necessary. Availability: Unix, Windows.
-
- Force write of file with filedescriptor fd to disk. Does not force update of
metadata. Availability: Unix.
-
- Return system configuration information relevant to an open file. name
specifies the configuration value to retrieve; it may be a string which is the name of a
defined system value; these names are specified in a number of standards (POSIX.1, Unix 95, Unix
98, and others). Some platforms define additional names as well. The names known to the
host operating system are given in the
pathconf_names dictionary. For
configuration variables not included in that mapping, passing an integer for name
is also accepted. Availability: Unix.
If name is a string and is not known, ValueError
is raised. If a specific value for name is not supported by the host system,
even if it is included in pathconf_names, an OSError
is raised with errno.EINVAL for the error number.
-
- Return status for file descriptor fd, like stat().
Availability: Unix, Windows.
-
- Return information about the filesystem containing the file associated with file
descriptor fd, like statvfs(). Availability: Unix.
-
- Force write of file with filedescriptor fd to disk. On Unix, this calls the native fsync()
function; on Windows, the MS _commit() function.
If you're starting with a Python file object f, first do f.flush(),
and then do os.fsync(f.fileno()), to ensure that all internal
buffers associated with f are written to disk. Availability: Unix, and Windows starting in 2.2.3.
-
- Truncate the file corresponding to file descriptor fd, so that it is at most length
bytes in size. Availability: Unix.
-
- Return
True if the file descriptor fd is open and connected to a
tty(-like) device, else False. Availability: Unix.
-
- Set the current position of file descriptor fd to position pos,
modified by how:
0 to set the position relative to the beginning
of the file; 1 to set it relative to the current position; 2 to
set it relative to the end of the file. Availability: Macintosh, Unix, Windows.
-
| open( |
file, flags[, mode]) |
- Open the file file and set various flags according to flags and
possibly its mode according to mode. The default mode is
0777
(octal), and the current umask value is first masked out. Return the file descriptor for
the newly opened file. Availability: Macintosh, Unix,
Windows.
For a description of the flag and mode values, see the C run-time documentation; flag
constants (like O_RDONLY and O_WRONLY)
are defined in this module too (see below).
Note: this function is intended for low-level I/O. For normal usage, use the built-in
function open(), which returns a ``file object'' with read() and write() methods (and many more).
-
- Open a new pseudo-terminal pair. Return a pair of file descriptors
(master,
slave) for the pty and the tty, respectively. For a (slightly) more
portable approach, use the pty
module. Availability: Some flavors of Unix.
-
- Create a pipe. Return a pair of file descriptors
(r, w)
usable for reading and writing, respectively. Availability: Unix, Windows.
-
- Read at most n bytes from file descriptor fd. Return a string
containing the bytes read. If the end of the file referred to by fd has been
reached, an empty string is returned. Availability: Macintosh, Unix, Windows.
Note: this function is intended for low-level I/O and must be applied to a file
descriptor as returned by open() or pipe().
To read a ``file object'' returned by the built-in function open()
or by popen() or fdopen(), or sys.stdin,
use its read() or readline() methods.
-
- Return the process group associated with the terminal given by fd (an open
file descriptor as returned by open()). Availability: Unix.
-
- Set the process group associated with the terminal given by fd (an open file
descriptor as returned by open()) to pg.
Availability: Unix.
-
- Return a string which specifies the terminal device associated with file-descriptor fd.
If fd is not associated with a terminal device, an exception is raised.
Availability: Unix.
-
- Write the string str to file descriptor fd. Return the number of
bytes actually written. Availability: Macintosh, Unix,
Windows.
Note: this function is intended for low-level I/O and must be applied to a file
descriptor as returned by open() or pipe().
To write a ``file object'' returned by the built-in function open()
or by popen() or fdopen(), or sys.stdout
or sys.stderr, use its write() method.
The following data items are available for use in constructing the flags
parameter to the open() function.
- O_RDONLY
-
- O_WRONLY
-
- O_RDWR
-
- O_NDELAY
-
- O_NONBLOCK
-
- O_APPEND
-
- O_DSYNC
-
- O_RSYNC
-
- O_SYNC
-
- O_NOCTTY
-
- O_CREAT
-
- O_EXCL
-
- O_TRUNC
- Options for the flag argument to the open()
function. These can be bit-wise OR'd together. Availability: Macintosh, Unix, Windows.
- O_BINARY
- Option for the flag argument to the open()
function. This can be bit-wise OR'd together with those listed above. Availability:
Macintosh, Windows.
- O_NOINHERIT
-
- O_SHORT_LIVED
-
- O_TEMPORARY
-
- O_RANDOM
-
- O_SEQUENTIAL
-
- O_TEXT
- Options for the flag argument to the open()
function. These can be bit-wise OR'd together. Availability: Windows.
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