#!perl
use strict;
use Data::Dump 'pp';

# test data
my @AoH = map{ 
   { line => $_, 
     eventid => int rand(2000)
   } } 1..8;

my $max = 6;
for (@AoH){
  if ($_->{'line'} > $max){
    $_->{'eventid'} = '';
  }
}
for (@AoH+1..$max){
  push @AoH, { 
    line    => $_,
    eventid => '' 
  };
}
pp \@AoH;