#!/usr/bin/perl
use strict; use warnings;

my $patchlist_file = shift @ARGV;
my %patchlist;

# read patchlist 
open my $PATCHLIST, '<', $patchlist_file 
  or die "Can't read $patchlist_file: $!";
while (<$PATCHLIST>) {
   s/^\s+|\s+$//sg; #trim head/tail whitespace incl. newline
   $patchlist{$_} = 1;
}
close $PATCHLIST;

#now check files against the patchlist
foreach my $file (@ARGV) {
   open my $FILE, '<', $file or do {
      warn "Unable to read $file: $!";
      next;
   };

   local $/ = "\n\n";  #records separated by double-newline

   while (<$FILE>) {
      my ($computer, @patches) = split("\n", $_, 2);
      my %patch = map { $_ => 1 } @patches;
      my @missing;
      
      # see if each patch is there
      for (keys %patchlist) { push @missing, $_ unless $patch{$_} }
      
      # report
      printf '%s is missing %d patches.', $computer, scalar @missing;
      print (scalar @missing ? ' They are: '.join(',',@missing) : ''),"\n";
   }

   close $FILE;
}