$_->dump_os for @agents;

# yields:
$VAR1 = [
          'SUN',
          'Solaris 8'
        ];
$VAR1 = [
          'IBM',
          'AIX  4.3.3'
        ];
# etc.

##</code><code>##

foreach (@agents) {
   $_->dump_os if grep /AIX/, @{$_->{os}};
}