my %values = (title => "A Title");

  sub get_value
  {
    my $key = shift;
    return exists($values{$key})
      ? $values{$key}
      : "UNKNOWN";
  }

  my $file = "User.htm";
  open IN, "<$file" or die "can't read file: $file";

  while (<IN>)
  {
    s/\$(\w+)/get_value($1)/ge;
    print;
  }