use strict;
use warnings;
$/ = q();
while (my $record = <DATA>) {
    my @lines = split /\n/, $record;
    my $header = shift @lines;
    my ($grpNm) = $header =~ /\:\s*(\w+)/;
    foreach (@lines) {
        my ($memID) = unpack '@12A6';
        print "$grpNm, $memID\n";
    }
}
__DATA__
cn: applegroup
 member: CN=mem001,OU=Users,DC=myorg,DC=com
 member: CN=mem002,OU=Users,DC=myorg,DC=com
 member: CN=mem003,OU=Users,DC=myorg,DC=com
 member: CN=mem004,OU=Users,DC=myorg,DC=com

cn: orangegroup
 member: CN=mem301,OU=Users,DC=myorg,DC=com
 member: CN=mem302,OU=Users,DC=myorg,DC=com
 member: CN=mem303,OU=Users,DC=myorg,DC=com

##</code><code>##

applegroup, mem001
applegroup, mem002
applegroup, mem003
applegroup, mem004
orangegroup, mem301
orangegroup, mem302
orangegroup, mem303