$logfile="log.txt";
$error=(/DOWN/);
$warn=(/PROBLEM/);
$redbutton="\<img src\=\'default_files/perlredblink2\.gif'>";
$greenbutton="\<img src\=\'default_files/perlgreenblink\.gif'>";
$yellowbutton="\<img src\=\'default_files/perlyellowblink\.gif'>";

open LOG, $logfile or die "Cannot open $logfile for read :$!";

@logarray=<LOG>;   # dumps all of $logfile into @logarray

chomp @logfile;
my $got_button = 0;
foreach my $line (@logarray) {
    if ($line eq $error) {
        $got_button = 1;
        print $redbutton;
        last;
      }
     elsif ($line eq $warn) {
        $got_button = 1;
        print $yellowbutton;
        last;
    }
  }
if (not $got_button) {
    print $greenbutton;
}