Offline HTML templating processor for Windows

$ cat page.html
<h1>A page</h1>
<!-- insert menu -->
<!-- menu ends -->
$ cat menu.tmpl
<ul id="#menu">…</ul>
$ update-templates page.html && cat page.html
<h1>A page</h1>
<!-- insert menu -->
<ul id="#menu">…</ul>
<!-- menu ends -->
$ echo "Moo" > menu.tmpl
$ update-templates page.html && cat page.html
<h1>A page</h1>
<!-- insert menu -->
Moo
<!-- menu ends -->

<!--#include file="menu.html" -->

sub readfile($) {
  open(FILE, 'r', shift);
  my $buffer;
  read (FILE, $buffer, 2 ** 20); # one megabyte maximum.
  close(FILE);
  return $buffer;
}
sub writefile($$) {
  open(FILE, 'w', shift);
  print FILE shift;
  close(FILE);
}

for my $file(@ARGV) {
  my $content = readfile($file);
  $content =~ s/<!--s+includes+(S+)s+-->.*?<!--s+ends+1s+-->/"<!-- include $1 -->".readfile($1)."<!-- end $1 -->"/ge;
  writefile($file, $content);
}

<p id='moo'></p>
<script type="text/javascript" src="moo.js"></script>

$('moo').innerHTML="hello world"

<html>
<head> ... whatever ...</head>
<body>
    <div id="menu">
        Item 1
        Item 2
        (this could even be generated automatically from the files)
    </div>
    <div id="content">
        <!-- CONTENT -->
    </div>
</body>
</html>

<p>This is my page content.</p>

$template = get_contents(page.tpl)
for each of the .txt files in the src directory {
    $c = get_contents($file)
    write(string_replace("<!-- CONTENT -->", $c, $template)) into page1.html
}

$ php script.php