The line break in your regexp is throwing off your match. If you make that a single line it ends up getting matches. What you end up with is a hash where the keys are "Service ..." all the way to the end of the text block and the values are "Host: <ip>" strings. So your keys are multi-line blocks of text and your values are strings that have IP's. That doesn't seem to be what you'd really want here but maybe it's a start.

You can also put that $/ setting once outside the loop. I find it good practice to local those but it doesn't matter much for a standalone piece of code.

I tested this version: 

use strict;
use warnings;

my $file = 'input.txt';

my (%hash, @ips, @alerts);

open (FILE, "$file") or die "Can't open $file\n";
local $/ = '-------------------------------------------------';

while (<FILE>){

   $hash{$2}{$1} = 0 
     if (/(Host: \d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}).*(Service:.*Sever
+ity:.*)/ms);
}

foreach my $key (keys %hash) {
    $hash{$key} = [keys %{$hash{$key}}];
}

my ($key, $values);
while (($key, $values) = each %hash) {
    print "$key --> ", join('|', @$values), "\n";
}

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In reply to Re: Building a Hash with Multiple Values by steves
in thread Building a Hash with Multiple Values by Dru

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