#!/usr/bin/perl
use warnings;
use strict;

my $dataStr = <<DATA;
Module: 1

ID:001

Customer : yes

Module: 2

ID:002

Customer : no

Module: 3

ID:003

Customer : yes

Module: 4

ID:004

Customer : no
DATA

my $filename = 'file.txt';
#open my $inFile, '<', $filename or die "Unable to open $filename: $!\n";
open my $inFile, '<', \$dataStr;

my $module;
my $id;

while (defined (my $line = <$inFile>)) {
    chomp ($line);
    if ($line =~ /Module:\s*(\S+)/) {
        $module = $1;
        next;
    }

    if ($line =~ /ID:\s*(\S+)/) {
        $line =~ /:\s*/;
        $id = $';
        next;
    }

    if ($line =~ /Customer : (\w+)/i) {
        print "$module and $id\n" if $1 eq 'yes';
        $module = '-- missing module --';
        $id = '-- missing ID --';
    }
}

##</code><code>##