I'll second that recommendation.

Your options are really C, perl or php.

C requires compiling for every change. It's (obviously) very powerful, but that means you can easily create some serious security issues.

perl is ideal for manipulating anything textual, and easily powerful enough to do the job. But it also suffers from the security issue as C. It's not necessarily easy to learn either - there's so many different ways to write one line of perl that do the same thing, that it's easy to write something that doesn't do quite what you wanted. perl won't complain...

But both of these languages were originally devised for other purposes.

PHP on the other hand was devised explicitly for the purpose of creating dynamic HTML, and as a language has been optimised to do this one task very well. It's syntax is fairly clean and easy to learn, and it's harder to create bone-headed security issues than with C or perl.