#Find the indext.txt config files 
#and edit the index.htm files one dir up from the config file
use warnings;
use HTML::TreeBuilder;
use File::Find;


my $dir = $ARGV[0];
my $html_file;
my $cfg_path;
my $index_pref;


find(\&file_finds, $dir);

sub file_finds{

	if ($_=/index.htm/){

		$html_file = $File::Find::name;
		$cfg_path = $File::Find::dir."/index/index.txt";
		&config;
		&edit;
	}
}

sub config{

	open (CF, "$cfg_path") or die ("Can't open $cfg_path $!");

	while (<CF>) {
    		chomp;                  # no newline
    		s/#.*//;                # no comments
    		s/^\s+//;               # no leading white
    		s/\s+$//;               # no trailing white
    		next unless length;     # anything left?
    		my ($var, $value) = split(/\s*=\s*/, $_, 2);
    		$index_pref{$var} = $value;
	}
	close CF;

}

sub edit{

	my $root = HTML::TreeBuilder->new_from_file($html_file)
  	or die qq{cant build tree\n}; 

	my $class1 = $root->look_down(
	_tag  => q{div}, 
	class => q{class1},
	);
	die qq{client not found\n$html_file\n} unless $class1;

	my $class2 = $root->look_down(
  	_tag  => q{div}, 
  	class => q{class2},
	);
	die qq{class2 not found\n$html_file\n} unless $class2;

	my $class3 = $root->look_down(
  	_tag  => q{div}, 
  	class => q{class3},
	);
	die qq{class3 not found\n$html_file\n} unless $class3;

	my $rep_class1;
	for my $item_r ($class1->content_refs_list) {
		
		next if ref ${$item_r};
  		${$item_r} = $index_pref{"class1"};
  		$rep_class1++;

	}
	die qq{Class1 not replaced\n$html_file\n} unless $rep_class1;

	my $rep_class2;
	for my $item_r ($class2->content_refs_list) {
  	
		next if ref ${$item_r};
  		${$item_r} = $index_pref{"class2"};
  		$rep_class2++;
	}
	die qq{Class2 not replaced\n$html_file\n} unless $rep_class2;

	my $rep_class3;
	for my $item_r ($class3->content_refs_list) {

  		next if ref ${$item_r};
	  	${$item_r} = $index_pref{"class3"};
  		$rep_class3++;

	}
	die qq{Class3 not replaced\n$html_file\n} unless $rep_class3;

	my $html = $root->as_HTML(undef, qq{  }, {});

	open (FH, ">$html_file") or die $!;
	print FH $html;
	close FH;
}

##</code><code>##

HTML:
<!--Class 3 has no text-->

<div align="center" class="class1">something</div>
<div align="center" class="class2">something else</div>
<div align="center" class="class3"></div>