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:mod:`pty` --- Pseudo-terminal utilities
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========================================
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:synopsis: Pseudo-Terminal Handling for Linux.
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.. moduleauthor:: Steen Lumholt
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.. sectionauthor:: Moshe Zadka <moshez@zadka.site.co.il>
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**Source code:** :source:`Lib/pty.py`
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The :mod:`pty` module defines operations for handling the pseudo-terminal
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concept: starting another process and being able to write to and read from its
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controlling terminal programmatically.
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Because pseudo-terminal handling is highly platform dependent, there is code to
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do it only for Linux. (The Linux code is supposed to work on other platforms,
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but hasn't been tested yet.)
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The :mod:`pty` module defines the following functions:
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Fork. Connect the child's controlling terminal to a pseudo-terminal. Return
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value is ``(pid, fd)``. Note that the child gets *pid* 0, and the *fd* is
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*invalid*. The parent's return value is the *pid* of the child, and *fd* is a
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file descriptor connected to the child's controlling terminal (and also to the
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child's standard input and output).
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.. function:: openpty()
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Open a new pseudo-terminal pair, using :func:`os.openpty` if possible, or
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emulation code for generic Unix systems. Return a pair of file descriptors
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``(master, slave)``, for the master and the slave end, respectively.
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.. function:: spawn(argv[, master_read[, stdin_read]])
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Spawn a process, and connect its controlling terminal with the current
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process's standard io. This is often used to baffle programs which insist on
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reading from the controlling terminal.
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The functions *master_read* and *stdin_read* should be functions which read from
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a file descriptor. The defaults try to read 1024 bytes each time they are
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.. versionchanged:: 3.4
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:func:`spawn` now returns the status value from :func:`os.waitpid`
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.. sectionauthor:: Steen Lumholt
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The following program acts like the Unix command :manpage:`script(1)`, using a
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pseudo-terminal to record all input and output of a terminal session in a
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parser = argparse.ArgumentParser()
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parser.add_argument('-a', dest='append', action='store_true')
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parser.add_argument('-p', dest='use_python', action='store_true')
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parser.add_argument('filename', nargs='?', default='typescript')
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options = parser.parse_args()
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shell = sys.executable if options.use_python else os.environ.get('SHELL', 'sh')
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filename = options.filename
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mode = 'ab' if options.append else 'wb'
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with open(filename, mode) as script:
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data = os.read(fd, 1024)
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print('Script started, file is', filename)
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script.write(('Script started on %s\n' % time.asctime()).encode())
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pty.spawn(shell, read)
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script.write(('Script done on %s\n' % time.asctime()).encode())
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print('Script done, file is', filename)