#!/usr/bin/perl -w

use strict;
 
my $ip = '192.168.1.4;
 
my $txt = 'Removed ' . $ip . ' by Dru';
 
my $file = '/data/syslog/log.backup';
 
open (FILE, "+<$file") or die "Can't open $file: $!\n";
 
while (<FILE>){
 
  if (/.*\b$ip\b.*/){
 
   # I thought this would work, but it doesn't
   s/$_/$txt/;
 
   print FILE;
 
  }
  
}