Path: csiph.com!usenet.pasdenom.info!gegeweb.org!usenet-fr.net!nerim.net!novso.com!newsfeed.xs4all.nl!newsfeed2.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
Return-Path: <oscar.j.benjamin@gmail.com>
X-Original-To: python-list@python.org
Delivered-To: python-list@mail.python.org
X-Spam-Status: OK 0.025
X-Spam-Evidence: '*H*': 0.95; '*S*': 0.00; 'explicitly': 0.05; 'sys': 0.07; 'cc:addr:python-list': 0.11; 'python': 0.11; 'windows': 0.15; 'assembler': 0.16; 'cc:name:python list': 0.16; 'descriptor': 0.16; 'ioerror:': 0.16; 'subject:Line': 0.16; 'subject:Reading': 0.16; 'tty': 0.16; 'wrote:': 0.18; 'obviously': 0.18; 'import': 0.22; 'shell': 0.22; 'cc:addr:python.org': 0.22; 'fine': 0.24; 'cc:2**0': 0.24; 'header:In-Reply-To:1': 0.27; 'tim': 0.29; "doesn't": 0.30; 'errors': 0.30; 'message- id:@mail.gmail.com': 0.30; '(on': 0.31; 'era': 0.31; 'file': 0.32; 'open': 0.33; '(most': 0.33; "can't": 0.35; 'test': 0.35; 'but': 0.35; 'received:google.com': 0.35; 'there': 0.35; 'described': 0.36; 'shows': 0.36; 'handle': 0.38; 'recent': 0.39; 'expect': 0.39; 'bad': 0.39; 'here:': 0.62; 'here': 0.66; 'yes': 0.68; 'default': 0.69; 'restore': 0.78; 'oscar': 0.84; 'subject:After': 0.84; 'subject:From': 0.97; '2013': 0.98
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type; bh=/PpZppGE/XmAcFX1g7hiM6JRY5qAcZ6Di4yX0WIfqzk=; b=hWKWCYPeohBa1gWpWOZ7nww8plYv+7UEnbweW1bdgwbuNTJ2aN57YKWarZRBsBFyq6 Auot8dWz0FvJ9mC7AGjpyFQdFNz10PGmiu4+ols7SA6OZsgn765KU5a3goVpb7kQYoG+ bNJTDd8BHV+U2y4fn/sTacXc9yBzRY3pb/F8gBxKNxD0UvRgi7qHyVGogUj0q9o/z5wM pw3eYdiESpiX0blQW17f/gPbPLp970UjnkwCaio3PeCuVHsAhQIEYnTbYuEzk0dWZMCk PvfO99J1yx7XlQUaKgzgDB7g1lRnzloKso6JXZ4nkvbNprMUdfDrRj1/Y3CCHU4AaXNf Mmyg==
X-Received: by 10.220.250.4 with SMTP id mm4mr12306vcb.47.1382614444722; Thu, 24 Oct 2013 04:34:04 -0700 (PDT)
MIME-Version: 1.0
In-Reply-To: <52686540.6000401@tundraware.com>
References: <7cdlja-j3j2.ln1@ozzie.tundraware.com> <7wli1jemvg.fsf@benfinney.id.au> <CAPTjJmr6VnTvc0rdPmadp5D39igweUAB1jZG_SgLO4qT9ak0Ug@mail.gmail.com> <1382562096.2967.37713425.4901765B@webmail.messagingengine.com> <mailman.1431.1382566824.18130.python-list@python.org> <52686540.6000401@tundraware.com>
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>
Content-Type: text/plain; charset=ISO-8859-1
Cc: Python List <python-list@python.org>
X-BeenThere: python-list@python.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe: <https://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive: <http://mail.python.org/pipermail/python-list/>
List-Post: <mailto:python-list@python.org>
List-Help: <mailto:python-list-request@python.org?subject=help>
List-Subscribe: <https://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Newsgroups: comp.lang.python
Message-ID: <mailman.1466.1382614452.18130.python-list@python.org>
Lines: 33
NNTP-Posting-Host: 2001:888:2000:d::a6
X-Trace: 1382614452 news.xs4all.nl 15903 [2001:888:2000:d::a6]:41679
X-Complaints-To: abuse@xs4all.nl
Xref: csiph.com comp.lang.python:57447

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