##
## USED WHEN YOU WANT TO TRAVERSE A LOGFILE AND ELIMINATE ANY DUPLICATE ENTRIES.
##
#!/usr/bin/perl -w
use strict;

my %seen;
my $logfile="/tmp/messages";
open(FILE, "<$logfile") or die "Unable to open $logfile :$!\n";
while(< FILE>) {
  my($domain,$ip,@rest) = split(/\s+/,$_);
  next if($seen{$ip}++);		# NEXT IF IP IS SEEN
  print "ENTRY: $_\n";
}
close(FILE);
exit(0);