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			94 lines
		
	
	
	
		
			2.9 KiB
		
	
	
	
		
			ReStructuredText
		
	
	
	
	
	
:mod:`pty` --- Pseudo-terminal utilities
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========================================
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.. module:: pty
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   :platform: Linux
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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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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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.. function:: fork()
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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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   called.
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Example
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-------
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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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"typescript". ::
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   import sys, os, time, getopt
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   import pty
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   mode = 'wb'
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   shell = 'sh'
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   filename = 'typescript'
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   if 'SHELL' in os.environ:
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       shell = os.environ['SHELL']
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   try:
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       opts, args = getopt.getopt(sys.argv[1:], 'ap')
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   except getopt.error as msg:
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       print('%s: %s' % (sys.argv[0], msg))
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       sys.exit(2)
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   for opt, arg in opts:
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       # option -a: append to typescript file
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       if opt == '-a':
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           mode = 'ab'
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       # option -p: use a Python shell as the terminal command
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       elif opt == '-p':
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           shell = sys.executable
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   if args:
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       filename = args[0]
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   script = open(filename, mode)
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   def read(fd):
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       data = os.read(fd, 1024)
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       script.write(data)
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       return data
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   sys.stdout.write('Script started, file is %s\n' % 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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   sys.stdout.write('Script done, file is %s\n' % filename)
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