How to remove special meaning of Control/S and Control/Q?
Mark-Jason Dominus
I have a friend who has an account on a VMS machine and an account
on a Unix machine. She can dial into the VMS machine but not into the
Unix machine. When she wants to dial in to the Unix machine, she dials
the VMS machine and uses `telnet' to connect to her Unix account.
When she types Control/S and Control/Q, the VMS machine interprets
them as requests to stop or to start transmission. We'd like these
characters to have no special meaning, and for VMS to pass them verbatim
through the telnet connection to the Unix processes at the other end.
How can we arrange this?
--
--
If you never did, / you should. / These things are fun / and fun is good.
Mark-Jason Dominus m...@central.cis.upenn.edu
Carl J Lydick
=
= I have a friend who has an account on a VMS machine and an account
=on a Unix machine. She can dial into the VMS machine but not into the
=Unix machine. When she wants to dial in to the Unix machine, she dials
=the VMS machine and uses `telnet' to connect to her Unix account.
=
= When she types Control/S and Control/Q, the VMS machine interprets
=them as requests to stop or to start transmission. We'd like these
=characters to have no special meaning, and for VMS to pass them verbatim
=through the telnet connection to the Unix processes at the other end.
=How can we arrange this?
Try:
$ SET TERMINAL/NOTTSYNC
--------------------------------------------------------------------------------
Carl J Lydick | INTERnet: CA...@SOL1.GPS.CALTECH.EDU | NSI/HEPnet: SOL1::CARL
Disclaimer: Hey, I understand VAXen and VMS. That's what I get paid for. My
understanding of astronomy is purely at the amateur level (or below). So
unless what I'm saying is directly related to VAX/VMS, don't hold me or my
organization responsible for it. If it IS related to VAX/VMS, you can try to
hold me responsible for it, but my organization had nothing to do with it.
Mighty Firebreather
>
> I have a friend who has an account on a VMS machine and an account
>on a Unix machine. She can dial into the VMS machine but not into the
>Unix machine. When she wants to dial in to the Unix machine, she dials
>the VMS machine and uses `telnet' to connect to her Unix account.
>
> When she types Control/S and Control/Q, the VMS machine interprets
>them as requests to stop or to start transmission. We'd like these
>characters to have no special meaning, and for VMS to pass them verbatim
>through the telnet connection to the Unix processes at the other end.
>How can we arrange this?
>
Try:
$ SET TERMINAL /NOHOSTSYNC /NOTTSYNC
This is not a good solution as it will disable all flow control
between the VAX and your friend's terminal. This will probably result in
lost characters sooner or later.
A better solution would be to remap the Ctrl-S and Ctrl-Q keys in
EMACS or whatever other brain damaged software uses these keys.
*************************************************************************
* Here, there be dragons! *
* dra...@nscvax.princeton.edu *
* *
* I'm job hunting. Any offers or leads will be appreciated. *
* Thanks! *
* Richard B. Gilbert *
*************************************************************************
Jerry Leichter
a Unix machine. She can dial into the VMS machine but not into the
Unix machine. When she wants to dial in to the Unix machine, she
dials the VMS machine and uses `telnet' to connect to her Unix
account.
When she types Control/S and Control/Q, the VMS machine interprets
them as requests to stop or to start transmission. We'd like these
characters to have no special meaning, and for VMS to pass them
verbatim through the telnet connection to the Unix processes at the
other end. How can we arrange this?
Let me guess: Your friend is using EMACS and wants to use CTRL/S to do an
i-search.
Simplest answer: You can't disable the special meanings. Fix EMACS - it has
no business gobbling up characters that have been reserved for many years for
flow control. Modern EMACS have a hook to rebind i-search and whatever is on
CTRL/Q to something else equally natural, and to ignore and CTRL/S or CTRL/Q
that might slip through thereafter.
Alternate answer: SET TERM/NOTTSYNC will tell VMS not to use CTRL/S and
CTRL/Q for flow control. *This may not work right*! VMS doesn't do padding
or play other games to allow terminals that need flow control to work. You'll
have to try it and see.
Also, be aware that some port multiplexors, terminal servers, and similar
devices use CTRL/S and CTRL/Q for flow control themselves. If one of those
is in the path between the terminal and the VAX, it may do no good to tell
VMS to not use flow control....
-- Jerry
Steve Suttles
> I have a friend who has an account on a VMS machine and an account
> on a Unix machine. She can dial into the VMS machine but not into the
> Unix machine. When she wants to dial in to the Unix machine, she dials
> the VMS machine and uses `telnet' to connect to her Unix account.
> When she types Control/S and Control/Q, the VMS machine interprets
> them as requests to stop or to start transmission. We'd like these
> characters to have no special meaning, and for VMS to pass them verbatim
> through the telnet connection to the Unix processes at the other end.
> How can we arrange this?
The straight answer is: tell VMS to SET TERMINAL/NOTTSYNC . At that point,
^S and ^Q become data to VMS.
However, the right answer is to find an alternative keystroke or method.
^S and ^Q are used for flow control at the hardware level in most applications.
(their ASCII names are XON and XOFF or DC1 and DC3 if you are old enough).
There is a more-likely-than-not chance that the modem on the vax is configured
to use ^S/^Q flow control to make the VAX shut up if it gets too far ahead.
About this your freind can do nothing. There is a slight possibility that the
VAX-unix line is serial and uses ^S/^Q. There is a fair likelihood that your
freinds modem or terminal (or terminal emulator on her PC) uses these
characters for flow control. Depending on her setup, she may also be stuck
with her choice.
If any of these communications links use ^S/^Q for their intended purpose,
turning them off on the vax would only make the situation worse. If your
freind finds that none of them are true, then she can use the SET command to
make VMS transparent to ^S/^Q, but it will only work in that configuration.
For these reasons, I recommend she use other commands to vi or emacs or
whatever is currently requiring ^S and ^Q. That's a harder thing to do
(involves unlearning habits), but in the long run is the right thing to do.
--
Steve Suttles Internet: st...@dbaccess.com Dr. DCL is IN!
CROSS ACCESS Corporation UUCP: {uunet,sgiblab}!troi!steve Yo speako TECO!
2900 Gordon Ave, Suite 100 fax: (408) 735-0328 Talk data to me!
Santa Clara, CA 95051-0718 vox: (408) 735-7545 HA! It's under 4 lines NOW!
Don Stokes
> Let me guess: Your friend is using EMACS and wants to use CTRL/S to do an
> i-search.
>
> Simplest answer: You can't disable the special meanings. Fix EMACS - it has
> no business gobbling up characters that have been reserved for many years for
> flow control. Modern EMACS have a hook to rebind i-search and whatever is on
> CTRL/Q to something else equally natural, and to ignore and CTRL/S or CTRL/Q
> that might slip through thereafter.
But ignoring Ctrl/S & Ctrl/Q is the wrong thing to do! After all, if
something is sending a Ctrl/S as flow control, maybe, just maybe, it's
because it wants flow to be controlled....
Personally, I think the Emacs usage of Ctrl/S as a search command counts
as one of the most braindamaged and arrogant things I've seen inflicted on
the world. (I also have a fundamental objection to any "text editor" that
is bigger than the operating system...)
--
Don Stokes, Network Manager, Victoria University of Wellington, New Zealand.
d...@zl2tnm.gen.nz(home) d...@vuw.ac.nz(work) +64 4 495-5052 Fax+64 4 471-5386