Perl Code required to break loop when key pressed

Question

I have a script which gets executed, but I require a loop which tells the process to sleep for 20-30 secs whilst a user runs a different test.

Once that test is completed then the user presses Enter to continue from where the script was halted. If Enter is not pressed within the 20-30 second period the script is to continue to run without user input.

I tried the following code but it pauses the script indefinitely – it does not continue after 20 secs, but it also does not accept Enter.

use Term::ReadKey;
ReadMode 4;
do {
    sleep 20; 
} until ( defined( $key = ReadKey(-1) ) );
ReadMode 0;

Demnogonis · Accepted Answer · 2013-07-15 05:19:35Z

1

Try a while loop instead of do{}

#!usr/bin/perl
use strict;
use warnings;
use Term::ReadKey;

ReadMode 4;    # Turn off controls keys
my $key;

while ( !defined( $key = ReadKey(-1) ) ) {
    print "No key yet\n";
    sleep 5;
}
print "Get key $key\n";

ReadMode 0;    # Reset tty mode before exiting

edited Jul 15, 2013 at 5:19

answered Jul 15, 2013 at 5:07

Demnogonis

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7 Comments

user2574644 Over a year ago

Thanks tried the provided code, and the output keeps posting 'No Key Yet' every 5 secs, even when I press any key, the output just keeps looping with 'No Key Yet', and does not jump to the next section. Seems it is not detecting the keystrokes.

Demnogonis Over a year ago

When I run this code it goes into the loop and exits it after I pressed a key. Just as intended. Which perl are you using? I tested this on Perl 5.14 on Ubuntu 13.04 64bit

user2574644 Over a year ago

Also am using Windows, and trying to obtain the keystroke from a HTML page if that helps.

user2574644 Over a year ago

Perl 5.8.7 on a UNIX environment, but calling via Windows (IE) a CGI/HTML script.

Demnogonis Over a year ago

So you are writing a web application? I used the command line. Try it in windows cmd. But I don't think that Term::Readkey is suitable for inputs from CGI. Try something similar with javascript on your HTML page. If no key is pressed the request is send with predefinded parameters.

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demongolem · Accepted Answer · 2014-01-28 21:24:21Z

1

Here's some code:

use Term::ReadKey;

ReadMode(4);
my $key;
my $wait = 20;

for (my $x = 0; $x < $wait; $x++) {
if (defined ($key = ReadKey(-1))) {
        print "key pressed\n";
        break;
    }
    print "waiting for key press\n";
    sleep(1);
}

edited Jan 28, 2014 at 21:24

demongolem

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answered Jan 28, 2014 at 21:01

David

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