Hi wishartz, I have a standard approach for this kind of problem.

Just put host and service information in anonymous hash trees and join them at the end.

Checking for host or service existence is very straightforward (look at the die statements)

Hope it helps.

Regs.

use strict;
use warnings;

our $hosts={};
$hosts->{hosta}->{ip}=192.168.1.1;
$hosts->{hostb}->{ip}=192.168.1.2;
$hosts->{hostc}->{ip}=192.168.1.3;
our $services={};
$services->{1}->{ID}=1;
$services->{1}->{name}='servicea';
$services->{1}->{startup}=sub { print "--> start service 1\n" };
$services->{2}->{ID}=2;
$services->{2}->{name}='serviceb';
$services->{2}->{startup}=sub { print "--> start service 2\n" };

$hosts->{hosta}->{services}->{1}=$services->{1};
$hosts->{hostb}->{services}->{1}=$services->{1};
$hosts->{hostc}->{services}->{2}=$services->{2};

print "--> type hostname\n";
my $host=<STDIN>;
chomp($host);
die "host unknown " unless exists $hosts->{$host};

print "--> which service do you want to use? (Type ID)\n";
while (my ($ID, $service) = each %{$hosts->{$host}->{services}}) 
{
   print "- ID $ID, name ".$service->{name}."\n";
}    
my $ID=<STDIN>;
chomp($ID);
die "service unknown " 
    unless exists $hosts->{$host}->{services}->{$ID};
&{$hosts->{$host}->{services}->{$ID}->{startup}};
exit;

---> output:
--> type hostname
hosta
--> which service do you want to use? (Type ID)
- ID 1, name servicea
1
--> start service 1
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