use strict;
use GDBM_File;

my $nis_domain="your_domain";
#location of nis files
my $passwd_byuid="/var/yp/".$nis_domain."/passwd.byuid"; 
my %nis;# informations from nis map
my @delete; # users not in the nis map
mu @user_info; # informations from /etc/passwd

## get the users from /etc/passwd ###
open (fd, '/etc/passwd') or die "can't access /etc/passwd";
my @CONTENTS = <fd>;
close (fd);

tie (%nis,'GDBM_File',$passwd_byname,0,0) or die "Can't access NIS passwd.byname";

foreach $line (@CONTENTS) {
  @user_info=split (/:/,$line);
  if (substr($user_info[0],0,1) eq "+") {
    $user_info[0]=~ s/\+//;
    if (!$nis{'$user_info[0]'}) {
      push @delete,$user_info[0];
      }
  }
}
untie (%nis);