How to subdue the keyboard? Post: 302946352

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Top Forums Shell Programming and Scripting How to subdue the keyboard? Post 302946352 by wisecracker on Monday 8th of June 2015 02:12:19 PM

06-08-2015

Registered User

How to subdue the keyboard?

This has got me stumped and no solution on the WWW or here either that I can see.

I suspect this can't be done... ;o(

My requirement is to hold a _random_ key down and run a single command.
Easy EXCEPT the keyboard keeps adding that same keystroke into a type ahead buffer somewhere and does NOT wait until the command has finished.

In this real example sleep is the command but almost any command does the same.
You will notice I have tried various ideas but all give the same results...

Take this real example, hold the s key down for 1 to 2 seconds and watch the results:-

Code:

#!/bin/bash
# exec 3<&0
while true
do
	KEY="?"
	stty -echo -icanon min 0 time 0
	KEY=$(dd bs=1 count=1 2> /dev/null)
	# Change -u[x] to the correct file descriptor.
	# read -s -n1 -u0 KEY
	KEY="${KEY:0:1}"
	if [ "$KEY" = "s" ]
	then
		sleep 0.5
		# wait
		printf "$KEY "
	fi
	if [ "$KEY" = "q" ]
	then
		break
	fi
done
stty sane
# exec 0<&3 3<&-
echo ""

Is it possible to just get one, and one only, ketstroke with the key depressed until the next loop just like INKEY$ in BASIC where each statement is executed sequentially?
View these incorrect results:-

Code:

Last login: Mon Jun  8 18:44:11 on ttys000
AMIGA:barrywalker~> cd ~/Desktop/Code/Shell
AMIGA:barrywalker~/Desktop/Code/Shell> ./kb
s s s s s s s s s s s s s 
AMIGA:barrywalker~/Desktop/Code/Shell> _

You will notice that sleep does its job of delaying the printout but it is printing a string of "s's" instead of one just "s" then waiting before accessing the next single character.

I hope this is lucid enough.

TIA.

Bazza...

wisecracker

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LEARN ABOUT DEBIAN

ureadkey

ureadkey(3alleg4)						  Allegro manual						 ureadkey(3alleg4)

NAME

       ureadkey - Returns the next unicode character from the keyboard buffer. Allegro game programming library.

SYNOPSIS

       #include <allegro.h>

       int ureadkey(int *scancode);

DESCRIPTION

       Returns	the  next character from the keyboard buffer, in Unicode format.  If the buffer is empty, it waits until a key is pressed. You can
       see if there are queued keypresses with keypressed(). The return value contains the Unicode value of the key, and if not NULL, the  pointer
       argument will be set to the scancode. Unlike readkey(), this function is able to return character values greater than 255. Example:

	  int val, scancode;
	  ...
	  val = ureadkey(&scancode);
	  if (val == 0x00F1)
	     allegro_message("You pressed n with tilde
");

	  if (val == 0x00DF)
	     allegro_message("You pressed sharp s
");

       You  should  be able to find Unicode character maps at http://www.unicode.org/. Remember that on DOS you must specify a custom keyboard map
       (like those found in `keyboard.dat') usually with the help of a configuration file specifying the language mapping  (keyboard  variable	in
       system section of `allegro.cfg'), or you will get the default US keyboard mapping.

SEE ALSO

       install_keyboard(3alleg4), readkey(3alleg4), keypressed(3alleg4), clear_keybuf(3alleg4), simulate_ukeypress(3alleg4), exkeys(3alleg4)

Allegro 							   version 4.4.2						 ureadkey(3alleg4)