As the data within define host{ ... } are effectively key/value pairs, you can capture that into a Perl hash then directly access host_name, address, etc. as required. 

#!/usr/bin/env perl

use strict;
use warnings;

my $define_re = qr{ \A define \s+ host \{ \s+ ( .*? ) \s+ \} \s* \z }m
+sx;
my $crit_dmz_re = qr{ (?> CRIT | DMZ ) }x;
my $out_format = qq{%s (%s) in groups: %s\n};

local $/ = ''; 

while (<DATA>) {
    /$define_re/;
    my %block = ( split /\s+/ => $1 );

    if ($block{hostgroups} =~ /$crit_dmz_re/) {
        printf $out_format => @block{qw{host_name address hostgroups}}
+;
    }   
}   

__DATA__
define host{
   use                                  HALF
   host_name                      denlas02
   alias                                denlas02
   address                           146.xxx.xxx.xxx
   hostgroups                      LINUX,DEN,DMZ
}

define host{
        use                             HALF
        host_name                 ppplas11
        alias                            ppplas11
        address                       10.xxx.xxx.xxx
        hostgroups                 LINUX,PPO,ORAPRD
        }

define host{
        use                               ALIVE
        host_name                   ppplas12
        alias                              ppplas12
        address                        10.50.33.26
        hostgroups                   LINUX,GRID,RMAN,CRIT
        }

[download]

Output:

$ pm_hosts_parse.pl
denlas02 (146.xxx.xxx.xxx) in groups: LINUX,DEN,DMZ
ppplas12 (10.50.33.26) in groups: LINUX,GRID,RMAN,CRIT

[download]

-- Ken

In reply to Re: split file on blank lines and match blocks by kcott
in thread split file on blank lines and match blocks by raggmopp

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