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Re: Reading From stdin After Command Line Redirection

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From Oscar Benjamin <oscar.j.benjamin@gmail.com>
Date Thu, 24 Oct 2013 12:33:44 +0100
Subject Re: Reading From stdin After Command Line Redirection
To Tim Daneliuk <tundra@tundraware.com>
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On 24 October 2013 01:09, Tim Daneliuk <tundra@tundraware.com> wrote:
>
> Now that I think about it, as I recall from the prehistoric era of writing
> lots of assembler and C, if you use shell redirection, stdin shows
> up as a handle to the file

Yes this is true. A demonstration using seek (on Windows but it is the
same in this sense):

$ cat test.py
import sys
sys.stdin.seek(0)
print('Seeked fine without errors')
$ python test.py
Traceback (most recent call last):
  File "test.py", line 2, in <module>
    sys.stdin.seek(0)
IOError: [Errno 9] Bad file descriptor
$ python test.py < other.dat
Seeked fine without errors

> and there is no way to retrieve/reset it
> its default association with the tty/pty.  Since python is layered on
> top of this, I expect the same would be the case here as well.

I think it is true that you cannot restore the association but you can
just open the tty explicitly as described here:
http://superuser.com/questions/569432/why-can-i-see-password-prompts-through-redirecting-output

(I can't test that right now as it obviously doesn't work on Windows).


Oscar

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Thread

Reading From stdin After Command Line Redirection Tim Daneliuk <tundra@tundraware.com> - 2013-10-23 12:25 -0500
  Re: Reading From stdin After Command Line Redirection Chris Angelico <rosuav@gmail.com> - 2013-10-24 07:40 +1100
  Re: Reading From stdin After Command Line Redirection Ben Finney <ben+python@benfinney.id.au> - 2013-10-24 07:46 +1100
  Re: Reading From stdin After Command Line Redirection Chris Angelico <rosuav@gmail.com> - 2013-10-24 07:52 +1100
  Re: Reading From stdin After Command Line Redirection random832@fastmail.us - 2013-10-23 17:01 -0400
  Re: Reading From stdin After Command Line Redirection Ben Finney <ben+python@benfinney.id.au> - 2013-10-24 09:20 +1100
    Re: Reading From stdin After Command Line Redirection Tim Daneliuk <tundra@tundraware.com> - 2013-10-23 19:09 -0500
      Re: Reading From stdin After Command Line Redirection Ben Finney <ben+python@benfinney.id.au> - 2013-10-24 14:53 +1100
        Re: Reading From stdin After Command Line Redirection Tim Daneliuk <tundra@tundraware.com> - 2013-10-23 23:36 -0500
        Re: Reading From stdin After Command Line Redirection Tim Daneliuk <tundra@tundraware.com> - 2013-10-23 23:39 -0500
        Re: Reading From stdin After Command Line Redirection Ben Finney <ben+python@benfinney.id.au> - 2013-10-24 15:54 +1100
          Re: Reading From stdin After Command Line Redirection Tim Daneliuk <tundra@tundraware.com> - 2013-10-24 06:58 -0500
          Re: Reading From stdin After Command Line Redirection Tim Daneliuk <tundra@tundraware.com> - 2013-10-24 06:58 -0500
            Re: Reading From stdin After Command Line Redirection Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2013-10-24 13:10 +0100
              Re: Reading From stdin After Command Line Redirection Tim Daneliuk <tundra@tundraware.com> - 2013-10-24 08:41 -0500
                Re: Reading From stdin After Command Line Redirection feedthetroll@gmx.de - 2013-10-24 07:36 -0700
                Re: Reading From stdin After Command Line Redirection Tim Daneliuk <tundra@tundraware.com> - 2013-10-24 09:43 -0500
              Re: Reading From stdin After Command Line Redirection Tim Daneliuk <tundra@tundraware.com> - 2013-10-24 08:41 -0500
                Re: Reading From stdin After Command Line Redirection Ethan Furman <ethan@stoneleaf.us> - 2013-10-24 07:30 -0700
      Re: Reading From stdin After Command Line Redirection Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-10-24 09:14 +0100
      Re: Reading From stdin After Command Line Redirection Ben Finney <ben+python@benfinney.id.au> - 2013-10-24 19:43 +1100
      Re: Reading From stdin After Command Line Redirection Tim Chase <python.list@tim.thechases.com> - 2013-10-24 05:45 -0500
      Re: Reading From stdin After Command Line Redirection Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2013-10-24 12:33 +0100
      Re: Reading From stdin After Command Line Redirection Ethan Furman <ethan@stoneleaf.us> - 2013-10-24 07:39 -0700
    Re: Reading From stdin After Command Line Redirection Tim Daneliuk <tundra@tundraware.com> - 2013-10-23 19:09 -0500
  Re: Reading From stdin After Command Line Redirection Chris Angelico <rosuav@gmail.com> - 2013-10-24 09:23 +1100

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