#! /usr/bin/perl
use 5.008;
use strict;
use warnings;
use threads;
use threads::shared;
 
our $Input : shared = "";

sub getInput {
    print "Please enter some- or nothing: ";
    my $input = <STDIN>; chomp($input);
    $Input = $input if defined $input; # or whatever...
}

my $oldInput = $Input;

my $inputThread = threads->create('getInput');

sleep 5;
unless ($Input eq $oldInput) {
    $inputThread->join();
    print "Input was: $Input\n";
    sleep 2;
}
else {
    print "Continuing with 'abcd' as a standard value...\n";
    # WHAT CAN I DO HERE ?
    
}