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LINUX / Keyboard echo during command execution [message #28272] Sun, 02 December 2001 00:31 Go to next message
Jeff Hester is currently offline  Jeff Hester
Messages: 21
Registered: December 2001
Junior Member
Under Linux (RedHat 7.1 / IDL 5.4) keyboard input entered during
execution of a procedure is echoed to the screen, leading to very
annoying behavior from routines that, for example, use get_kbrd() to
poll the keyboard during execution. This behavior is different from my
previous environment (DEC UNIX / IDL 5.4). I am running the SawFish
window manager and GNOME, although the behavior persists under KDE as
well.

To see the problem, enter
wait,5
and during the wait, see if keyboard input is echoed. Characters should
not appear on the screen until after the wait completes, but in my
current environment, they do.

I have tried obvious things like stty settings and using different
flavored terminal emulators. The only thing that I have found that
fixes the problem is to manually enter a ^S (XOFF) from the keyboard.
Then characters that are entered are snarfed up by get_kbrd() and never
appear on the screen. But that is not a practical real-world solution.
(Spitting out a ^S to stdout with writeu does not fix the problem...)

Any ideas would be greatly appreciated. I have an analysis environment
that runs in a loop, polling both the keyboard and the cursor for
positioning and command information, and the echoing of characters typed
on the keyboard but not destined for the IDL command intepreter is
seriously cramping my style.


Jeff Hester
Professor
Department of Physics & Astronomy
Arizona State University
jhester@asu.edu
Re: LINUX / Keyboard echo during command execution [message #28353 is a reply to message #28272] Mon, 03 December 2001 11:21 Go to previous message
Craig Markwardt is currently offline  Craig Markwardt
Messages: 1869
Registered: November 1996
Senior Member
Jeff Hester <jhester@asu.edu> writes:


> Under Linux (RedHat 7.1 / IDL 5.4) keyboard input entered during
> execution of a procedure is echoed to the screen, leading to very
> annoying behavior from routines that, for example, use get_kbrd() to
> poll the keyboard during execution. This behavior is different from my
> previous environment (DEC UNIX / IDL 5.4). I am running the SawFish
> window manager and GNOME, although the behavior persists under KDE as
> well.
>
> To see the problem, enter
> wait,5
> and during the wait, see if keyboard input is echoed. Characters should
> not appear on the screen until after the wait completes, but in my
> current environment, they do.

Hi Jeff--

For every version of Linux IDL I tried, including 5.1 and 5.2,
characters are echoed during a WAIT.

Craig

--
------------------------------------------------------------ --------------
Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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