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X-Authentication-Warning: slinky.cs.nyu.edu: pechtcha owned process doing -bs
Date: Fri, 25 Oct 2002 10:31:04 -0400 (EDT)
From: Igor Pechtchanski <pechtcha AT cs DOT nyu DOT edu>
Reply-To: cygwin AT cygwin DOT com
To: Jim Rainville <jrainville AT valosystems DOT com>
cc: cygwin AT cygwin DOT com
Subject: RE: console output problem
In-Reply-To: <D8BB1D1FB113524E95EEF65D595C89BF127D3E@CORVAIR.valosystems.com>
Message-ID: <Pine.GSO.4.44.0210251022210.13770-100000@slinky.cs.nyu.edu>
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Jim,

It would be very hard to redirect stdin *to* /dev/null, as stdin is an
input stream...  You could, however, redirect it *from* /dev/null.

Even though stdin is not read, some applications test whether they're
running in a tty by checking where stdin comes from.  Redirecting it from
/dev/null lets the applications know that their input comes from a file
rather than a console, and they wouldn't be trying to open the console (to
set tty parameters, for example, or buffering).  Some applications also
*do* try to read stdin, and continue upon encountering an EOF.

Redirecting stdin from /dev/null is a standard trick in standalone scripts
that don't take any input.  It should work just fine in a cygwin shell
(sh/bash/tcsh/zsh) using the "script < /dev/null" syntax.  I believe
Windows also has an input redirection operator ('<').  The best way to
check is to try it and see...
	Igor

On Fri, 25 Oct 2002, Jim Rainville wrote:

> Hi Igor -
> Thanks for the response.
> I didn't redirect stdin but why would I need to? I just want to redirect
> stdout and stderr to a log file. Stdin should come from the console but
> there is no console input (unless args to applications are stdin).
> You're suggesting I redirect stdin to /dev/null? Would this work in
> windows? What would be the effect?
>
> Thanks.
> Jim
>
> -----Original Message-----
> From: Igor Pechtchanski [mailto:pechtcha AT cs DOT nyu DOT edu]
> Sent: Friday, October 25, 2002 6:21 AM
> To: Jim Rainville
> Cc: cygwin AT cygwin DOT com
> Subject: Re: console output problem
>
> On Fri, 25 Oct 2002, Jim Rainville wrote:
>
> > Hi  -
> >
> > I'm trying to set up a perl build script that runs every night, builds a
> > bunch of code (using gcc) and saves the output to some log files. So I
> > redirect stdout and stderr to some files and run the script that builds
> > the  load. This runs fine when I run it from the command prompt but when
> > I run it from the windows scheduler I get a bunch of errors of the form:
> >
> >       0 [main] cpp 1001 fhandler_console::de_linearize: error opening console after exec, errno 13, Win32 error 5
> >       0 [main] cc1 1002 fhandler_console::de_linearize: error opening console after exec, errno 13, Win32 error 5
> >       0 [main] as 1003 fhandler_console::de_linearize: error opening console after exec, errno 13, Win32 error 5
> >       0 [main] cpp 1001 fhandler_console::de_linearize: error opening console after exec, errno 13, Win32 error 5
> >       0 [main] cc1 1002 fhandler_console::de_linearize: error opening console after exec, errno 13, Win32 error 5
> >       0 [main] as 1003 fhandler_console::de_linearize: error opening console after exec, errno 13, Win32 error 5
> >
> > It looks like since the scheduler doesn't have a console associated with
> > it the fhandler_console throws an error even though stdout is
> > redirected. Has anybody come across this before? Any clues how to fix
> > it?
> >
> > Thanks. Jim
>
> Jim,
>
> Did you also remember redirect stdin from /dev/null?
>         Igor

-- 
				http://cs.nyu.edu/~pechtcha/
      |\      _,,,---,,_		pechtcha AT cs DOT nyu DOT edu
ZZZzz /,`.-'`'    -.  ;-;;,_		igor AT watson DOT ibm DOT com
     |,4-  ) )-,_. ,\ (  `'-'		Igor Pechtchanski
    '---''(_/--'  `-'\_) fL	a.k.a JaguaR-R-R-r-r-r-.-.-.  Meow!

"Water molecules expand as they grow warmer" (C) Popular Science, Oct'02, p.51


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