Re: tcgetattr: Invalid argument and --ctrl-c

[Ole Tange]

Did you test the new release and see if "tcgetattr: Invalid argument" is gone?

/Ole

On Mon, May 13, 2013 at 6:57 PM, Fratkin, Allyn <allyn@hp.com> wrote:
> Excellent sleuthing.
>
> Unfortunately there are a lot of old OpenSSH versions out there.
>
> My RHEL5.8 system has OpenSSH_4.3p2, which has the problem and my RHEL6.3 
> system has OpenSSH_5.3p1, which still has the problem.  So it seems that any 
> RHEL user will have the problem.
>
> If it was up to me I think this means that --ctrl-c should default to off.  
> I'll leave the resolution up to you but please make sure if --ctrl-c is 
> turned on by default there is a way to turn it off.
>
> Thank you.
>
> --
> Allyn Fratkin                    allyn@hp.com
> Hewlett-Packard Company          http://www.fratkin.com/
>
>
> -----Original Message-----
> From: ole.tange@gmail.com [mailto:ole.tange@gmail.com] On Behalf Of Ole Tange
> Sent: Saturday, May 11, 2013 9:03 AM
> To: Fratkin, Allyn
> Cc: parallel@gnu.org
> Subject: Re: tcgetattr: Invalid argument and --ctrl-c
>
> On Thu, May 9, 2013 at 8:11 PM, Fratkin, Allyn <allyn@hp.com> wrote:
>
>> Perhaps the error is specific to Red Hat?  I reproduced it with remote hosts 
>> running RHEL 5.2, 5.8, 6.3.  The local host is RHEL 5.8.
>>
>> ANY invocation of stty, even without arguments, provokes the "tcgetattr: 
>> Invalid argument" error message.
>>
>> [afratkin@vl001 src]$ echo hello | ssh -tt -oLogLevel=quiet g4t0930c stty | 
>> cat # RHEL 5.2
>> tcgetattr: Invalid argument
>
> The problem is not due to stty, but due to the version of ssh.
>
> $ ./ssh -V
> OpenSSH_3.6.1p2, SSH protocols 1.5/2.0, OpenSSL 0x1000100f
> $ true | ./ssh -tt lo echo FOO
> tcsetattr: Invalid argument
> FOO
> Connection to lo closed.
>
> $ ssh -V
> OpenSSH_5.9p1 Debian-5ubuntu1.1, OpenSSL 1.0.1 14 Mar 2012
> $ true | ssh -tt lo echo FOO
> FOO
> Connection to lo closed.
>
> The problem is due to this line in OpenSSH:
>
> sshtty.c:
>   enter_raw_mode(void):
>   [...]
>      if (tcsetattr(fileno(stdin), TCSADRAIN, &tio) == -1)
>                 perror("tcsetattr");
>
> The error does not harm, but it would be nice if it was possible to
> ignore it. I have not found a way.
>
> I see several options:
>
>   * live with the error on systems that use an old version of ssh
>
>   * go back to the situation where --ctrl-c is not default (thus
> ctrl-c will no propagate to remote hosts)
>
>   * find a way to give each ssh a pty (openpty() looks promising
> except it seems not to work on old versions of Perl). This might make
> it possible to also propagate ctrl-z to suspend remote jobs if
> parallel is suspended, which would be neat.
>
>   * find a way to ignore the error in ssh. A dirty way of doing that
> is when printing the cached stderr: Skip the first line if it is
> "tcsetattr: Invalid argument". This would of course only work if
> stderr is cached (i.e. not --ungroup).
>
>
> /Ole