:mod:`pty` --- Pseudo-terminal utilities
========================================

.. module:: pty
   :platform: IRIX, Linux
   :synopsis: Pseudo-Terminal Handling for SGI and Linux.
.. moduleauthor:: Steen Lumholt
.. sectionauthor:: Moshe Zadka <moshez@zadka.site.co.il>


The :mod:`pty` module defines operations for handling the pseudo-terminal
concept: starting another process and being able to write to and read from its
controlling terminal programmatically.

Because pseudo-terminal handling is highly platform dependent, there is code to
do it only for SGI and Linux. (The Linux code is supposed to work on other
platforms, but hasn't been tested yet.)

The :mod:`pty` module defines the following functions:


.. function:: fork()

   Fork. Connect the child's controlling terminal to a pseudo-terminal. Return
   value is ``(pid, fd)``. Note that the child  gets *pid* 0, and the *fd* is
   *invalid*. The parent's return value is the *pid* of the child, and *fd* is a
   file descriptor connected to the child's controlling terminal (and also to the
   child's standard input and output).


.. function:: openpty()

   Open a new pseudo-terminal pair, using :func:`os.openpty` if possible, or
   emulation code for SGI and generic Unix systems. Return a pair of file
   descriptors ``(master, slave)``, for the master and the slave end, respectively.


.. function:: spawn(argv[, master_read[, stdin_read]])

   Spawn a process, and connect its controlling terminal with the current
   process's standard io. This is often used to baffle programs which insist on
   reading from the controlling terminal.

   The functions *master_read* and *stdin_read* should be functions which read from
   a file descriptor. The defaults try to read 1024 bytes each time they are
   called.