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X-Authentication-Warning: slinky.cs.nyu.edu: pechtcha owned process doing -bs
Date: Sun, 8 Aug 2004 11:44:49 -0400 (EDT)
From: Igor Pechtchanski <pechtcha AT cs DOT nyu DOT edu>
Reply-To: cygwin AT cygwin DOT com
To: "David E. Meier" <dev AT eth0 DOT ch>
cc: cygwin AT cygwin DOT com
Subject: Re: Redirect stdout from SSH
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On Fri, 6 Aug 2004, David E. Meier wrote:

> > At 01:03 PM 8/3/2004, you wrote:
> >>Hello list,
> >>
> >>I am writing a program in C# that calls some cygwin programs and redirects
> >>the standard output and error to a textbox. This works excellent with
> >>calls like "ls -al" or rsync.
> >>
> >>However, I cannot read the output generated by SSH. When I issue a command
> >>like "ssh user AT host ls -al" I can observe some network action but the
> >>application stalls, uses 100% CPU and never spits out something. The same
> >>command in the cygwin shell executes with the result expected. Since I use
> >>public key authentication SSH is not waiting for any login information.
> >>
> >>Is this a configuration issue of SSH? Thanks for any help. Dave.
> >
> > Not AFAICS.  A small C program that invokes Cygwin's 'ssh' via 'system()'
> > with 'ls -al' works fine for me.  Does that work for you?
>
> I got it working when standard input is also set to be redirected. Does
> anyone have an explanation of this?
>
> Dave

By default, ssh is an interactive program, even if the program it invokes
isn't.  Therefore, ssh contains some code that sets up standard input and
its properties.  This code may cause some problems when invoked from a
non-pty-aware application (such as a C# program).  You can redirect
standard input, as you've already discovered, or simply use the '-n'
option to ssh.
	Igor
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