use strict;
use warnings;

our $children;
our $new_kids;

FORK: {
    if ( !$children ) {
        print 'How many children to start with? [5]: ';
        $children = <>;
        chomp $children;
        unless ($children) { $children = '5'; }
        die "only numbers for kids, please\n\n" if $children =~ /\D/;
        
        for ( 1..$children ) {
            my $child;
            my $signal = $_;

            die "Can't fork: $!" unless defined ($child = fork());
            if ($child == 0) {
            # i'm the child!
                &dummy();
            } else {
            # i'm the parent
                while ( $signal ge $children ) {
                    &interact();
                    redo FORK;
                }
            }
        }
    } else {
        for ( 0..$new_kids ) {
            my $child;
            my $signal = $_;

            die "Can't fork: $!" unless defined ($child = fork());
            if ($child == 0) {
            # i'm the child!
                &dummy();
            } else {
            # i'm the parent
                while ( $signal ge $new_kids ) {
                    &interact();
                    redo FORK;
                }
            }
        }
    }       
}

sub dummy() { 
    sleep 90;
    exit;   
}

sub interact() {
    print 'Current number of children is: ', "$children", '. i.e. these:', "\n\n"; 
    system('ps -ef | grep tryMore | grep -v grep');
    print "\n\n";
    print 'Minus one for the parent, of course', "\n\n"; 
    print 'How many children do you want to add? [1]: ';
    my $new_kids = <>;
    chomp $new_kids;
    $new_kids = '0' unless $new_kids;
    unless($new_kids) { $children += 1; } else { $children += $new_kids; }
    return; 
}