It sounds like you want something like this: 

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

my $hostfile = '/tmp/jn/hosts';
my $logfile  = '/tmp/jn/logforthisserver.log';

open HOSTFILE, '<', $hostfile or die "Cannot open '$hostfile' $!";

my %unique_ips;
while ( <HOSTFILE> ) {
    next if /^(?:#|\s*$)/;
    my $ip = inet_aton( ( split )[ 0 ] );
    $unique_ips{ $ip }++;
    }

close HOSTFILE;


open LOGFILE, '>', $logfile or die "Cannot open '$logfile' $!";

for my $ip ( sort keys %unique_ips ) {
    print LOGFILE inet_ntoa( $ip ), "\n";
    }

close LOGFILE;

[download]

In reply to Re: removing a column by jwkrahn
in thread removing a column by jn64024

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.