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Added safeguard against failure in __del__.
author Guido van Rossum <guido@python.org>
date Wed, 27 Nov 1996 19:39:58 +0000
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1 \section{Built-in Module \sectcode{termios}}
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2 \bimodindex{termios}
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3 \indexii{Posix}{I/O control}
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4 \indexii{tty}{I/O control}
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5
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6 \renewcommand{\indexsubitem}{(in module termios)}
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7
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8 This module provides an interface to the Posix calls for tty I/O
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9 control. For a complete description of these calls, see the Posix or
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10 \UNIX{} manual pages. It is only available for those \UNIX{} versions
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11 that support Posix \code{termios} style tty I/O control (and then
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12 only if configured at installation time).
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13
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14 All functions in this module take a file descriptor \var{fd} as their
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15 first argument. This must be an integer file descriptor, such as
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16 returned by \code{sys.stdin.fileno()}.
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17
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18 This module should be used in conjunction with the \code{TERMIOS}
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19 module, which defines the relevant symbolic constants (see the next
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20 section).
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21
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22 The module defines the following functions:
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23
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24 \begin{funcdesc}{tcgetattr}{fd}
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25 Return a list containing the tty attributes for file descriptor
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26 \var{fd}, as follows: \code{[\var{iflag}, \var{oflag}, \var{cflag},
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27 \var{lflag}, \var{ispeed}, \var{ospeed}, \var{cc}]} where \var{cc} is
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28 a list of the tty special characters (each a string of length 1,
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29 except the items with indices \code{VMIN} and \code{VTIME}, which are
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30 integers when these fields are defined). The interpretation of the
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31 flags and the speeds as well as the indexing in the \var{cc} array
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32 must be done using the symbolic constants defined in the
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33 \code{TERMIOS} module.
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34 \end{funcdesc}
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35
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36 \begin{funcdesc}{tcsetattr}{fd\, when\, attributes}
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37 Set the tty attributes for file descriptor \var{fd} from the
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38 \var{attributes}, which is a list like the one returned by
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39 \code{tcgetattr()}. The \var{when} argument determines when the
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40 attributes are changed: \code{TERMIOS.TCSANOW} to change immediately,
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41 \code{TERMIOS.TCSADRAIN} to change after transmitting all queued
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42 output, or \code{TERMIOS.TCSAFLUSH} to change after transmitting all
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43 queued output and discarding all queued input.
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44 \end{funcdesc}
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45
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46 \begin{funcdesc}{tcsendbreak}{fd\, duration}
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47 Send a break on file descriptor \var{fd}. A zero \var{duration} sends
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48 a break for 0.25--0.5 seconds; a nonzero \var{duration} has a system
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49 dependent meaning.
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50 \end{funcdesc}
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51
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52 \begin{funcdesc}{tcdrain}{fd}
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53 Wait until all output written to file descriptor \var{fd} has been
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54 transmitted.
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55 \end{funcdesc}
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56
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57 \begin{funcdesc}{tcflush}{fd\, queue}
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58 Discard queued data on file descriptor \var{fd}. The \var{queue}
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59 selector specifies which queue: \code{TERMIOS.TCIFLUSH} for the input
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60 queue, \code{TERMIOS.TCOFLUSH} for the output queue, or
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61 \code{TERMIOS.TCIOFLUSH} for both queues.
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62 \end{funcdesc}
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63
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64 \begin{funcdesc}{tcflow}{fd\, action}
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65 Suspend or resume input or output on file descriptor \var{fd}. The
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66 \var{action} argument can be \code{TERMIOS.TCOOFF} to suspend output,
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67 \code{TERMIOS.TCOON} to restart output, \code{TERMIOS.TCIOFF} to
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68 suspend input, or \code{TERMIOS.TCION} to restart input.
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69 \end{funcdesc}
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70
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71 \subsection{Example}
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72 \nodename{termios Example}
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73
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74 Here's a function that prompts for a password with echoing turned off.
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75 Note the technique using a separate \code{termios.tcgetattr()} call
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76 and a \code{try {\ldots} finally} statement to ensure that the old tty
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77 attributes are restored exactly no matter what happens:
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78
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79 \begin{verbatim}
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80 def getpass(prompt = "Password: "):
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81 import termios, TERMIOS, sys
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82 fd = sys.stdin.fileno()
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83 old = termios.tcgetattr(fd)
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84 new = termios.tcgetattr(fd)
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85 new[3] = new[3] & ~TERMIOS.ECHO # lflags
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86 try:
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87 termios.tcsetattr(fd, TERMIOS.TCSADRAIN, new)
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88 passwd = raw_input(prompt)
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89 finally:
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90 termios.tcsetattr(fd, TERMIOS.TCSADRAIN, old)
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91 return passwd
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92 \end{verbatim}
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93
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94
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95 \section{Standard Module \sectcode{TERMIOS}}
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96 \stmodindex{TERMIOS}
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97 \indexii{Posix}{I/O control}
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98 \indexii{tty}{I/O control}
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99
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100 \renewcommand{\indexsubitem}{(in module TERMIOS)}
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101
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102 This module defines the symbolic constants required to use the
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103 \code{termios} module (see the previous section). See the Posix or
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104 \UNIX{} manual pages (or the source) for a list of those constants.
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105
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106 Note: this module resides in a system-dependent subdirectory of the
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107 Python library directory. You may have to generate it for your
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108 particular system using the script \file{Tools/scripts/h2py.py}.