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110 lines
4.2 KiB
TeX
110 lines
4.2 KiB
TeX
\section{Built-in Module \sectcode{termios}}
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\label{module-termios}
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\bimodindex{termios}
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\indexii{\POSIX{}}{I/O control}
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\indexii{tty}{I/O control}
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\setindexsubitem{(in module termios)}
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This module provides an interface to the \POSIX{} calls for tty I/O
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control. For a complete description of these calls, see the \POSIX{} or
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\UNIX{} manual pages. It is only available for those \UNIX{} versions
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that support \POSIX{} \code{termios} style tty I/O control (and then
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only if configured at installation time).
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All functions in this module take a file descriptor \var{fd} as their
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first argument. This must be an integer file descriptor, such as
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returned by \code{sys.stdin.fileno()}.
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This module should be used in conjunction with the \code{TERMIOS}
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module, which defines the relevant symbolic constants (see the next
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section).
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The module defines the following functions:
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\begin{funcdesc}{tcgetattr}{fd}
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Return a list containing the tty attributes for file descriptor
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\var{fd}, as follows: \code{[\var{iflag}, \var{oflag}, \var{cflag},
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\var{lflag}, \var{ispeed}, \var{ospeed}, \var{cc}]} where \var{cc} is
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a list of the tty special characters (each a string of length 1,
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except the items with indices \code{VMIN} and \code{VTIME}, which are
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integers when these fields are defined). The interpretation of the
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flags and the speeds as well as the indexing in the \var{cc} array
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must be done using the symbolic constants defined in the
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\code{TERMIOS} module.
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\end{funcdesc}
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\begin{funcdesc}{tcsetattr}{fd\, when\, attributes}
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Set the tty attributes for file descriptor \var{fd} from the
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\var{attributes}, which is a list like the one returned by
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\code{tcgetattr()}. The \var{when} argument determines when the
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attributes are changed: \code{TERMIOS.TCSANOW} to change immediately,
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\code{TERMIOS.TCSADRAIN} to change after transmitting all queued
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output, or \code{TERMIOS.TCSAFLUSH} to change after transmitting all
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queued output and discarding all queued input.
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\end{funcdesc}
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\begin{funcdesc}{tcsendbreak}{fd\, duration}
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Send a break on file descriptor \var{fd}. A zero \var{duration} sends
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a break for 0.25--0.5 seconds; a nonzero \var{duration} has a system
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dependent meaning.
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\end{funcdesc}
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\begin{funcdesc}{tcdrain}{fd}
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Wait until all output written to file descriptor \var{fd} has been
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transmitted.
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\end{funcdesc}
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\begin{funcdesc}{tcflush}{fd\, queue}
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Discard queued data on file descriptor \var{fd}. The \var{queue}
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selector specifies which queue: \code{TERMIOS.TCIFLUSH} for the input
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queue, \code{TERMIOS.TCOFLUSH} for the output queue, or
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\code{TERMIOS.TCIOFLUSH} for both queues.
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\end{funcdesc}
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\begin{funcdesc}{tcflow}{fd\, action}
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Suspend or resume input or output on file descriptor \var{fd}. The
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\var{action} argument can be \code{TERMIOS.TCOOFF} to suspend output,
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\code{TERMIOS.TCOON} to restart output, \code{TERMIOS.TCIOFF} to
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suspend input, or \code{TERMIOS.TCION} to restart input.
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\end{funcdesc}
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\subsection{Example}
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\nodename{termios Example}
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Here's a function that prompts for a password with echoing turned off.
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Note the technique using a separate \code{termios.tcgetattr()} call
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and a \code{try \ldots{} finally} statement to ensure that the old tty
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attributes are restored exactly no matter what happens:
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\begin{verbatim}
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def getpass(prompt = "Password: "):
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import termios, TERMIOS, sys
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fd = sys.stdin.fileno()
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old = termios.tcgetattr(fd)
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new = termios.tcgetattr(fd)
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new[3] = new[3] & \~TERMIOS.ECHO # lflags
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try:
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termios.tcsetattr(fd, TERMIOS.TCSADRAIN, new)
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passwd = raw_input(prompt)
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finally:
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termios.tcsetattr(fd, TERMIOS.TCSADRAIN, old)
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return passwd
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\end{verbatim}
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\section{Standard Module \sectcode{TERMIOS}}
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\label{module-TERMIOSuppercase}
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\stmodindex{TERMIOS}
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\indexii{\POSIX{}}{I/O control}
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\indexii{tty}{I/O control}
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\setindexsubitem{(in module TERMIOS)}
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This module defines the symbolic constants required to use the
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\code{termios} module (see the previous section). See the \POSIX{} or
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\UNIX{} manual pages (or the source) for a list of those constants.
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\refbimodindex{termios}
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Note: this module resides in a system-dependent subdirectory of the
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Python library directory. You may have to generate it for your
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particular system using the script \file{Tools/scripts/h2py.py}.
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