how do I disable the generation of XOFFs when using tip over aserial port to another device

[Jeff Haran]

> -----Original Message-----
> From: Wayne Sierke [mailto:ws at au.dyndns.ws] 
> Sent: Saturday, September 06, 2008 1:12 AM
> To: Jeff Haran
> Cc: freebsd-questions at freebsd.org
> Subject: Re: how do I disable the generation of XOFFs when 
> using tip over aserial port to another device
> 
> On Fri, 2008-09-05 at 12:20 -0700, Jeff Haran wrote:
> > Dear Sirs,
> > 
> > I have connected one of the RS232 ports of my PC with 
> FreeBSD (v6.3) on
> > it to a device that does not understand XON/XOFF flow 
> control. I run the
> > tip program to connect to that device.
> > 
> > How do I configure tip and/or the serial port so that the FreeBSD PC
> > will NOT send XOFFs or XONs to the device?
> > 
> > When I run:
> > 
> > stty -a -f /dev/cuad0
> > 
> > where /dev/cuad0 is the device associated with the port, it outputs
> > (among other things):
> > 
> > iflags: ... ixon -ixoff ...
> > 
> > >From my reading of the stty man page, I would think that 
> means the port
> > is already configured to not send XOFFs.
> > 
> > Is there something I need to do to /etc/remote to tell tip 
> to not enable
> > XON/XOFF?
> > 
> > Please respond to this email address as I do not subscribe to the
> > mailing list.
> > 
> > Thanks,
> > 
> > Jeff Haran
> 
> Hi Jeff,
> 
> I think there might be a problem with the man page for tip(1) 
> on 6.x, as
> an entry for 'tandem' was added to the tip sources about 2 years ago.
> It's in the 7.x man page as you can see at:
> 
> http://www.freebsd.org/cgi/man.cgi?query=tip&manpath=FreeBSD+7
.0-RELEASE&format=html
> 
> in 'Variables'. 'tandem' shows up in a variable listing (~v) 
> in tip on a
> 6.x system I have here but I don't have an appropriate set up 
> at hand to
> verify that it operates correctly.
> 
> Let us know how you go with it. If it works for you then a PR would be
> in order.
> 
> 
> Wayne
> 
> [1] Extract from the tip(1) man page on 7.x:
>      tandem  (bool) Use XON/XOFF flow control to throttle 
> data from the remote
>              host; abbreviated ta.  The default value is true 
> unless the nt
>              capability has been specified in /etc/remote, in 
> which case the
>              default value is false.
> 

Wayne,

Thanks for the response. After I sent the original email, I found the
tandem variable in the tip source code and toggling it off did indeed
disable the generation of XOFFs. It would have been easier if tandem had
been documented in the 6.3 man pages.

It would also be convenient if there was some way to set these tip
varibles non-interactively (e.g. via a command line option, .rc file or
some such thing). I am using tip in an expect script to automate a test
case and coding the expect script to generate the ~s escape sequence to
turn tandem off was something less than straight forward.

Jeff Haran