cpython/Doc/library/termios.rst

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:mod:`termios` --- POSIX style tty control
==========================================
.. module:: termios
:platform: Unix
:synopsis: POSIX style tty control.
.. index::
pair: POSIX; I/O control
pair: tty; I/O control
--------------
This module provides an interface to the POSIX calls for tty I/O control. For a
complete description of these calls, see :manpage:`termios(2)` Unix manual
page. It is only available for those Unix versions that support POSIX
*termios* style tty I/O control configured during installation.
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All functions in this module take a file descriptor *fd* as their first
argument. This can be an integer file descriptor, such as returned by
``sys.stdin.fileno()``, or a :term:`file object`, such as ``sys.stdin`` itself.
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This module also defines all the constants needed to work with the functions
provided here; these have the same name as their counterparts in C. Please
refer to your system documentation for more information on using these terminal
control interfaces.
The module defines the following functions:
.. function:: tcgetattr(fd)
Return a list containing the tty attributes for file descriptor *fd*, as
follows: ``[iflag, oflag, cflag, lflag, ispeed, ospeed, cc]`` where *cc* is a
list of the tty special characters (each a string of length 1, except the
items with indices :const:`VMIN` and :const:`VTIME`, which are integers when
these fields are defined). The interpretation of the flags and the speeds as
well as the indexing in the *cc* array must be done using the symbolic
constants defined in the :mod:`termios` module.
.. function:: tcsetattr(fd, when, attributes)
Set the tty attributes for file descriptor *fd* from the *attributes*, which is
a list like the one returned by :func:`tcgetattr`. The *when* argument
determines when the attributes are changed: :const:`TCSANOW` to change
immediately, :const:`TCSADRAIN` to change after transmitting all queued output,
or :const:`TCSAFLUSH` to change after transmitting all queued output and
discarding all queued input.
.. function:: tcsendbreak(fd, duration)
Send a break on file descriptor *fd*. A zero *duration* sends a break for 0.25
--0.5 seconds; a nonzero *duration* has a system dependent meaning.
.. function:: tcdrain(fd)
Wait until all output written to file descriptor *fd* has been transmitted.
.. function:: tcflush(fd, queue)
Discard queued data on file descriptor *fd*. The *queue* selector specifies
which queue: :const:`TCIFLUSH` for the input queue, :const:`TCOFLUSH` for the
output queue, or :const:`TCIOFLUSH` for both queues.
.. function:: tcflow(fd, action)
Suspend or resume input or output on file descriptor *fd*. The *action*
argument can be :const:`TCOOFF` to suspend output, :const:`TCOON` to restart
output, :const:`TCIOFF` to suspend input, or :const:`TCION` to restart input.
.. seealso::
Module :mod:`tty`
Convenience functions for common terminal control operations.
.. _termios-example:
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Example
-------
Here's a function that prompts for a password with echoing turned off. Note the
technique using a separate :func:`tcgetattr` call and a :keyword:`try` ...
:keyword:`finally` statement to ensure that the old tty attributes are restored
exactly no matter what happens::
Merged revisions 74779-74786,74793,74795,74811,74860-74861,74863,74876,74886,74896,74901,74903,74908,74912,74930,74933,74943,74946,74952-74955,75015,75019,75032,75068,75076,75095,75098,75102,75129,75139,75230 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r74779 | michael.foord | 2009-09-13 11:13:36 -0500 (Sun, 13 Sep 2009) | 1 line Change to tutorial wording for reading text / binary files on Windows. Issue #6301. ........ r74780 | michael.foord | 2009-09-13 11:40:02 -0500 (Sun, 13 Sep 2009) | 1 line Objects that compare equal automatically pass or fail assertAlmostEqual and assertNotAlmostEqual tests on unittest.TestCase. Issue 6567. ........ r74781 | michael.foord | 2009-09-13 11:46:19 -0500 (Sun, 13 Sep 2009) | 1 line Note that sys._getframe is not guaranteed to exist in all implementations of Python, and a corresponding note in inspect.currentframe. Issue 6712. ........ r74782 | michael.foord | 2009-09-13 12:07:46 -0500 (Sun, 13 Sep 2009) | 1 line Tutorial tweaks. Issue 6849. ........ r74783 | michael.foord | 2009-09-13 12:28:35 -0500 (Sun, 13 Sep 2009) | 1 line unittest.TestLoader.loadTestsFromName honors the loader suiteClass attribute. Issue 6866. ........ r74784 | georg.brandl | 2009-09-13 13:15:07 -0500 (Sun, 13 Sep 2009) | 1 line Typo fix. ........ r74785 | michael.foord | 2009-09-13 14:07:03 -0500 (Sun, 13 Sep 2009) | 1 line Test discovery in unittest will only attempt to import modules that are importable; i.e. their names are valid Python identifiers. If an import fails during discovery this will be recorded as an error and test discovery will continue. Issue 6568. ........ r74786 | michael.foord | 2009-09-13 14:08:18 -0500 (Sun, 13 Sep 2009) | 1 line Remove an extraneous space in unittest documentation. ........ r74793 | georg.brandl | 2009-09-14 09:50:47 -0500 (Mon, 14 Sep 2009) | 1 line #6908: fix association of hashlib hash attributes. ........ r74795 | benjamin.peterson | 2009-09-14 22:36:26 -0500 (Mon, 14 Sep 2009) | 1 line Py_SetPythonHome uses static storage #6913 ........ r74811 | georg.brandl | 2009-09-15 15:26:59 -0500 (Tue, 15 Sep 2009) | 1 line Add Armin Ronacher. ........ r74860 | benjamin.peterson | 2009-09-16 21:46:54 -0500 (Wed, 16 Sep 2009) | 1 line kill bare except ........ r74861 | benjamin.peterson | 2009-09-16 22:18:28 -0500 (Wed, 16 Sep 2009) | 1 line pep 8 defaults ........ r74863 | benjamin.peterson | 2009-09-16 22:27:33 -0500 (Wed, 16 Sep 2009) | 1 line rationalize a bit ........ r74876 | georg.brandl | 2009-09-17 11:15:53 -0500 (Thu, 17 Sep 2009) | 1 line #6932: remove paragraph that advises relying on __del__ being called. ........ r74886 | benjamin.peterson | 2009-09-17 16:33:46 -0500 (Thu, 17 Sep 2009) | 1 line use macros ........ r74896 | georg.brandl | 2009-09-18 02:22:41 -0500 (Fri, 18 Sep 2009) | 1 line #6936: for interactive use, quit() is just fine. ........ r74901 | georg.brandl | 2009-09-18 04:14:52 -0500 (Fri, 18 Sep 2009) | 1 line #6905: use better exception messages in inspect when the argument is of the wrong type. ........ r74903 | georg.brandl | 2009-09-18 04:18:27 -0500 (Fri, 18 Sep 2009) | 1 line #6938: "ident" is always a string, so use a format code which works. ........ r74908 | georg.brandl | 2009-09-18 08:57:11 -0500 (Fri, 18 Sep 2009) | 1 line Use str.format() to fix beginner's mistake with %-style string formatting. ........ r74912 | georg.brandl | 2009-09-18 11:19:56 -0500 (Fri, 18 Sep 2009) | 1 line Optimize optimization and fix method name in docstring. ........ r74930 | georg.brandl | 2009-09-18 16:21:41 -0500 (Fri, 18 Sep 2009) | 1 line #6925: rewrite docs for locals() and vars() a bit. ........ r74933 | georg.brandl | 2009-09-18 16:35:59 -0500 (Fri, 18 Sep 2009) | 1 line #6930: clarify description about byteorder handling in UTF decoder routines. ........ r74943 | georg.brandl | 2009-09-19 02:35:07 -0500 (Sat, 19 Sep 2009) | 1 line #6944: the argument to PyArg_ParseTuple should be a tuple, otherwise a SystemError is set. Also clean up another usage of PyArg_ParseTuple. ........ r74946 | georg.brandl | 2009-09-19 03:43:16 -0500 (Sat, 19 Sep 2009) | 1 line Update bug tracker reference. ........ r74952 | georg.brandl | 2009-09-19 05:42:34 -0500 (Sat, 19 Sep 2009) | 1 line #6946: fix duplicate index entries for datetime classes. ........ r74953 | georg.brandl | 2009-09-19 07:04:16 -0500 (Sat, 19 Sep 2009) | 1 line Fix references to threading.enumerate(). ........ r74954 | georg.brandl | 2009-09-19 08:13:56 -0500 (Sat, 19 Sep 2009) | 1 line Add Doug. ........ r74955 | georg.brandl | 2009-09-19 08:20:49 -0500 (Sat, 19 Sep 2009) | 1 line Add Mark Summerfield. ........ r75015 | georg.brandl | 2009-09-22 05:55:08 -0500 (Tue, 22 Sep 2009) | 1 line Fix encoding name. ........ r75019 | vinay.sajip | 2009-09-22 12:23:41 -0500 (Tue, 22 Sep 2009) | 1 line Fixed a typo, and added sections on optimization and using arbitrary objects as messages. ........ r75032 | benjamin.peterson | 2009-09-22 17:15:28 -0500 (Tue, 22 Sep 2009) | 1 line fix typos/rephrase ........ r75068 | benjamin.peterson | 2009-09-25 21:57:59 -0500 (Fri, 25 Sep 2009) | 1 line comment out ugly xxx ........ r75076 | vinay.sajip | 2009-09-26 09:53:32 -0500 (Sat, 26 Sep 2009) | 1 line Tidied up name of parameter in StreamHandler ........ r75095 | michael.foord | 2009-09-27 14:15:41 -0500 (Sun, 27 Sep 2009) | 1 line Test creation moved from TestProgram.parseArgs to TestProgram.createTests exclusively. Issue 6956. ........ r75098 | michael.foord | 2009-09-27 15:08:23 -0500 (Sun, 27 Sep 2009) | 1 line Documentation improvement for load_tests protocol in unittest. Issue 6515. ........ r75102 | skip.montanaro | 2009-09-27 21:12:27 -0500 (Sun, 27 Sep 2009) | 3 lines Patch from Thomas Barr so that csv.Sniffer will set doublequote property. Closes issue 6606. ........ r75129 | vinay.sajip | 2009-09-29 02:08:54 -0500 (Tue, 29 Sep 2009) | 1 line Issue #7014: logging: Improved IronPython 2.6 compatibility. ........ r75139 | raymond.hettinger | 2009-09-29 13:53:24 -0500 (Tue, 29 Sep 2009) | 3 lines Issue 7008: Better document str.title and show how to work around the apostrophe problem. ........ r75230 | benjamin.peterson | 2009-10-04 08:38:38 -0500 (Sun, 04 Oct 2009) | 1 line test logging ........
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def getpass(prompt="Password: "):
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import termios, sys
fd = sys.stdin.fileno()
old = termios.tcgetattr(fd)
new = termios.tcgetattr(fd)
new[3] = new[3] & ~termios.ECHO # lflags
try:
termios.tcsetattr(fd, termios.TCSADRAIN, new)
passwd = input(prompt)
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finally:
termios.tcsetattr(fd, termios.TCSADRAIN, old)
return passwd