X-Recipient:	archive-cygwin AT delorie DOT com
X-SWARE-Spam-Status:	No, hits=-10.2 required=5.0 tests=AWL,BAYES_00,KHOP_PGP_SIGNED,KHOP_RCVD_UNTRUST,KHOP_THREADED,RCVD_IN_DNSWL_HI,SPF_HELO_PASS,T_RP_MATCHES_RCVD
X-Spam-Check-By:	sourceware.org
Message-ID:	<4FE23FDE.9070506@redhat.com>
Date:	Wed, 20 Jun 2012 15:25:50 -0600
From:	Eric Blake <eblake AT redhat DOT com>
User-Agent:	Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0
MIME-Version:	1.0
To:	cygwin AT cygwin DOT com
Subject:	Re: piping input to executable reading from /dev/tty?
References:	<4FE1FB4F DOT 3020808 AT kempt DOT net> <4FE1FD33 DOT 3070009 AT redhat DOT com> <4FE23EB0 DOT 2020406 AT kempt DOT net>
In-Reply-To:	<4FE23EB0.2020406@kempt.net>
OpenPGP:	url=http://people.redhat.com/eblake/eblake.gpg
X-IsSubscribed:	yes
Mailing-List:	contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Id:	<cygwin.cygwin.com>
List-Subscribe:	<mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive:	<http://sourceware.org/ml/cygwin/>
List-Post:	<mailto:cygwin AT cygwin DOT com>
List-Help:	<mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender:	cygwin-owner AT cygwin DOT com
Mail-Followup-To:	cygwin AT cygwin DOT com
Delivered-To:	mailing list cygwin AT cygwin DOT com

--------------enig96F5D8FDB9D14810173620F2
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

On 06/20/2012 03:20 PM, Dan B. wrote:
> Eric Blake wrote:
>> On 06/20/2012 10:33 AM, Dan B. wrote:
>>> Is there any way to redirect /dev/tty similarly to how stdin can be
>>> redirected (e.g., like "echo ... | someexecutable")?
>>
>> Yes; use 'expect'.
>>
>>> Does Cygwin (or Unix/Linux, for that matter) have any equivalent way
>>> of redirecting /dev/tty?
>>>
>>> Can /dev/tty be redirected at all?  (I would guess that something
>>> could be done with pseudoterminals, but I know very little about
>>> them.)
>>
>> Yes, 'expect' is the command line tool that lets you script around
>> programs that expect to be run interactively, but where you want to
>> script the input that your program will see.
>=20
> Does expect use only redirection of file descriptors, or can it also
> redirect references to /dev/tty?

expect uses pseudoterminals so that the stdin of the child process is
also its /dev/tty (remember, /dev/tty is a magic name that resolves to
the current controlling terminal, and that a pseutoterminal can be a
controlling terminal).  Therefore, anything that normally requires you
to interactively type something because the child process opened
/dev/tty can be run under expect, where opening /dev/tty in the child
will now be asking expect for the input, and expect then hands it the
information that you wrote into your expect script.  This is not
cygwin-specific, so you may get better support by looking for help on
using 'expect'.

--=20

Eric Blake   eblake AT redhat DOT com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org




--------------enig96F5D8FDB9D14810173620F2
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: OpenPGP digital signature
Content-Disposition: attachment; filename="signature.asc"

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.12 (GNU/Linux)
Comment: Public key at http://people.redhat.com/eblake/eblake.gpg
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/

iQEcBAEBCAAGBQJP4j/eAAoJEKeha0olJ0NqUYAIAIGmTkLp/s7d5xOxznZe6DI9
84YS7+cTNjhq28w13ylBj5Sr/DGXk9XT/qLQwu28dZxqRMYEhh+dqTg8zJWG8AFZ
YE7vDOxsklqMI+UTmykhflfCmik+nTkLe0SHdp5W+f8vhSFSxtCE13RJ/o2LKLLU
/7MmfALY6hR6gatqGF7ILINqsPef/tnbUbfniuqw8xPkT/0syqKxTAUNwUqiLJ37
jYTFEPVVgiwNg6DdtMoYnLc4/pcmkPpzuRbgYlIRRxNn59zaiQzUa55lYu/6YfC1
EHQ64LPHJmpfjoh803BWpCdQyXv6+czrb3cj3biXqQFX8lFkXTKz3lhyVpiLpmM=
=wTDo
-----END PGP SIGNATURE-----

--------------enig96F5D8FDB9D14810173620F2--

- Raw text -