stty Invalid argument

[Tom Sanders]

Unix System V, Release 3.1
--------------------------

I am trying to write a shell script which will set up a set of tty
options and exec a process.  Simple enough, I thought, but I get
the error message:

  stty: : Invalid argument

Briefly, the problem has been traced to a number of options on the stty
command.  For example,

  stty igncr < /dev/tty6

will produce the error message.  However,

  stty -igncr < /dev/tty6

is OK!!   Other options which behave this way are isig, icanon, olcuc
and more.  The negative form is OK, the positive form not.  If the
printer scheduler interface scripts can do it, why cant I?

Any info gratefully received.

Regards,
Tom Sanders
-- 
Tom Sanders  <tom at tcom.stc.co.uk>
             STC Telecomms, Oakleigh Rd South, London N11 1HB UK.