#!/usr/bin/perl -w
#<UnusedGrp.pl> Find unused Groups in /etc/group
use strict;

my $GROUPfile="/etc/group";
my $gfpid = open(GFILE, "<$GROUPfile") or die "$GROUPfile File Not Found: $!\n";
my $PASSWD="/etc/passwd";
my $pfpid = open(PFILE, "<$PASSWD") or die "$PASSWD File Not Found: $!\n";
my @PWLINES = <PFILE>;
my @GIDS = map { (split /:/)[3] } @PWLINES;

while (my $line = <GFILE>) {
   my @GRP = split(/:/, $line);
   if (length($GRP[3]) < 2){
     #print "$GRP[0]:$GRP[2] is zero length\n";
     if ( ! (grep $_ eq $GRP[2], @GIDS)) {
       print "$GRP[0]:$GRP[2] is Empty & not referenced in /etc/passwd\n";
     }
   }
}