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110 lines
4.2 KiB
TeX
110 lines
4.2 KiB
TeX
\section{Built-in Module \module{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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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{} \emph{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
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\module{TERMIOS}\refstmodindex{TERMIOS} module, which defines the
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relevant symbolic constants (see the next 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}\code{]} where
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\var{cc} is a list of the tty special characters (each a string of
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length 1, except the items with indices \constant{TERMIOS.VMIN} and
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\constant{TERMIOS.VTIME}, which are integers when these fields are
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defined). The interpretation of the flags and the speeds as well as
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the indexing in the \var{cc} array must be done using the symbolic
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constants defined in the \module{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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\function{tcgetattr()}. The \var{when} argument determines when the
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attributes are changed: \constant{TERMIOS.TCSANOW} to change
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immediately, \constant{TERMIOS.TCSADRAIN} to change after transmitting
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all queued output, or \constant{TERMIOS.TCSAFLUSH} to change after
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transmitting all 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: \constant{TERMIOS.TCIFLUSH} for the
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input queue, \constant{TERMIOS.TCOFLUSH} for the output queue, or
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\constant{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 \constant{TERMIOS.TCOOFF} to suspend
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output, \constant{TERMIOS.TCOON} to restart output,
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\constant{TERMIOS.TCIOFF} to suspend input, or
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\constant{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
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off. Note the technique using a separate \function{tcgetattr()} call
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and a \keyword{try} ... \keyword{finally} statement to ensure that the
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old tty 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 \module{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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This module defines the symbolic constants required to use the
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\module{termios}\refbimodindex{termios} module (see the previous
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section). See the \POSIX{} or \UNIX{} manual pages (or the source)
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for a list of those constants.
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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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