[4559] in Athena Bugs
RT 6.0R: stty -echo is a nop; extra control-M's
daemon@ATHENA.MIT.EDU (Jonathan I. Kamens)
Sun Mar 18 07:18:16 1990
Date: Sun, 18 Mar 90 07:18:05 -0500
From: "Jonathan I. Kamens" <jik@pit-manager.MIT.EDU>
To: Saltzer@ATHENA.MIT.EDU
Cc: bugs@ATHENA.MIT.EDU, tytso@ATHENA.MIT.EDU
In-Reply-To: bugs[1967]
Date: Thu, 23 Mar 89 15:42:08 gmt
From: Jerome H Saltzer <jhs%computer-lab.cambridge.ac.uk@NSS.Cs.Ucl.AC.UK>
1. The command "stty -echo" doesn't seem to do anything on the RT;
the echo mode acts as if it is permanently wired in the ON position.
On a VAX (I tried only paris, not a microvax) it properly turns the
echo mode OFF.
Echo mode isn't often switched off within Athena, but the version of
telnet I am using is designed for satellite hops and long-delay links,
so it works in local echo line-at-a-time mode, for which one prefers
to turn off the second echo from the tty driver.
2. Every line sent by an Athena RT on a telnet connection is ended by
two or more control-M's preceding the control-J. The Athena Vaxes
send exactly one control-M every time. (Noticed while the machine at
this end was in debugging mode.)
I have investigated both of these bug reports and, believe it or
not, both of them are attributable to "lineedit" mode of our shell.
In fact, I'm not even sure that the first one is a bug per se. I've
CC'd this message to Ted, since he's the most tcsh-knowledgeable
person on the staff right now, in case he has anything to add to my
comments (or in case he can give us a fix for the bugs for our next
release :-).
Re "stty -echo": lineedit mode does all kinds of funky things to the
terminal modes, including, apparently, ignoring when you turn off echo
mode. If you unset lineedit and then disable echo, it works. There's
good reason for this -- lineedit mode would have a tough time working
without echo. By the way, when lineedit is set, "stty -echo" doesn't
work on EITHER a Vax or an RT.
Re telnet: The extra 0d and 00 (hex) characters at the end of every
line are apparently sent only when lineedit mode is turned on; once
again, this is true on either the Vax or the RT. I am not sure why
the extra characters are there, but I suspect that they are sent by
the tcsh portion of the shell output driver, and then the second 0d is
sent by the csh portion of the output driver.
I suspect that when you did your testing, your dot files on the RT
had lineedit enabled (your home directory, perhaps?), and the dot
files on the Vax (paris, perhaps?) didn't.
Jonathan Kamens
Project Athena Quality Assurance
P.S. I am sorry for the somewhat... um... untimely response to your
reports.
