Mail Archives: cygwin/2002/07/16/12:11:50
My best understanding is that, at present, inetutils does not provide
support for pseudo-terminals. As a result, the Cygwin 'expect' does not
have a properly functioning 'spawn'. Until someone can contribute the
pty support to inetutils, the Cygwin 'expect' should probably be avoided
for most expect scripts.
From the 'TODO' file for inetutils-1.3.2:
"Add support for sysv-style ptys, whatever that is."
> -----Original Message-----
> From: David Shapiro [mailto:david DOT shapiro AT btitele DOT com]
> Sent: Wednesday, July 03, 2002 8:23 AM
> To: 'Ville Herva'; cygwin AT cygwin DOT com
> Subject: RE: Expect and ssh
>
>
> I agree that public key authentication is best. Here is even
> another way
> (gotta love unix type things --- million ways to do the same
> thing!): perl
> and its expect module works fine:
>
> #!/usr/local/bin/perl -w
>
> use strict;
> use Expect;
>
> # Optional debugging, explained later.
> #$Expect::Debug=1;
> #$Expect::Exp_Internal=1;
> #$Expect::Log_Stdout=0; # On by default.
>
> # Could put a loop here with different host names so you can
> ssh to multiple
> servers...
> my $hostname = "put_server_name_here";
> my $user = "put_user_name_here";
>
> my $ssh = Expect->spawn("ssh -l $user $hostname")) or
> return "Couldn't spawn ssh connection, ".$ssh->exp_error()."\n";
>
> unless ($ssh->expect(30,-re,'#')) {
> return "Never got the prompt on $hostname during login,
> ".$ssh->exp_error()."\n";
> }
> $ssh->clear_accum();
>
> my $cmd = "/usr/bin/ls";
> print $ssh "$cmd\r";
>
> # Now we look for a prompt, having (we hope) successfully logged in.
> unless ($ssh->expect(30,-re,'#')) {
> return "Never got ssh prompt after sending command $cmd
> ".$ssh->exp_error()."\n";
> }
> my $read = $ssh->exp_before();
> my @read = split (/\cM/,$read);
> @read now has all the ls stuff.
> .
> .
> .
> # do another command --- weee!
>
>
>
> -----Original Message-----
> From: Ville Herva [mailto:vherva AT niksula DOT hut DOT fi]
> Sent: Wednesday, July 03, 2002 4:11 AM
> To: cygwin AT cygwin DOT com
> Subject: Re: Expect and ssh
>
>
> On Tue, Jul 02, 2002 at 06:26:54PM -0400, you [Arthur Taylor] wrote:
> > Someone had a similar issue to this in May... But I didn't see any
> > follow up...
> > Arthur
> >
> > Sample expect script:
> >
> > ---------------------
> >
> > #! /usr/bin/expect -f
> >
> > spawn /usr/bin/ssh <name>@<host>
> > expect "password:"
> > send "<password>\r"
> > expect ">"
> > send "ls -l\r"
> > expect ">"
> > send "exit\r"
> > exit
>
> First: Any particular reason you are not using public key
> authentication?
> You just need to
>
> ssh-keygen -t dsa
> (store the keys somewhere safe)
> append the pub key to remotehost:~user/.ssh/authorized_keys2
>
> then just
>
> ssh -i <path to priv key> <name>@<host> "ls -l"
>
> You can use empty passphrases for the keys - that's not less
> safe than your
> expect case - but it's always better to have a passphrase.
> Also, you can
> limit the command allowed for that particular key from the
> remote end by
> specifying the command in
> remotehost:~user/.ssh/authorized_keys2 after the
> key. Then anyone who gets access to that particular private
> key can only
> execute "ls -l" or so.
>
> As for your problem: I imagine your script does not work, because ssh
> (I'm looking at openssh-3.4) checks in function
> readpass.c:read_passphrase()
> whether stdin is a TTY (in your case it's not) and then tries
> to to use
> ssh_askpass, /dev/tty etc. Have a look at the code yourself.
>
> lftp had the same problem in its ssh-code, I'm not sure how
> they solved it.
>
>
> -- v --
>
> v AT iki DOT fi
>
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