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

while (my $line = <DATA>)
{
   (my $group) = $line =~ /cn:\s+(\w+)/;
   
   process_record($group) if $group;  
}

sub process_record
{
   my $group = shift;
   my $line;
   while (defined ($line = <DATA>) and $line !~ /^\s*$/)
   {
     (my @columns) = $line =~ /=(\w+)/g;
     print join ',',($group,@columns); 
     print "\n";
   }
}
  
=example printout
applegroup,mem001,Users,myorg,com
applegroup,mem002,Users,myorg,com
applegroup,mem003,Users,myorg,com
applegroup,mem004,Users,myorg,com
orangegroup,mem301,Users,myorg,com
orangegroup,mem302,Users,myorg,com
orangegroup,mem303,Users,myorg,com
=cut

__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