in reply to Because PHP sucks: escape to Perl.

FWIW: I use a very similar trick all the time in conjunction with SSI, where the polyglot ends up looking like this:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="de" lang="de">
<head>
<title>foobar</title>
</head>
<body>
<!--#exec cmd="perl -x $SCRIPT_FILENAME" -->
</body>
</html>
<!--#if expr="0 = 1" -->
#!/usr/bin/perl

# generate page body here

__END__
<!--#endif -->

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It’s actually quite neat as a crude templating system when the script-generated part of the page has little to no variation in markup structure (f.ex. just a simple table or list).

Makeshifts last the longest.

In Section Cool Uses for Perl