Many posters have problems debugging their RewriteRule and RewriteCond statements within their .htaccess
files. Most of these are using a shar
I found this question while trying to debug my mod_rewrite issues, and it definitely has some helpful advice. But in the end the most important thing is to make sure you have your regex syntax correct. Due to problems with my own RE syntax, installing the regexpCheck.php script was not a viable option.
But since Apache uses Perl-Compatible Regular Expressions (PCRE)s, any tool which helps writing PCREs should help. I've used RegexPlanet's tool with Java and Javascript REs in the past, and was happy to find that they support Perl as well.
Just type in your regular expression and one or more example URLs, and it will tell you if the regex matches (a "1" in the "~=" column) and if applicable, any matching groups (the numbers in the "split" column will correspond to the numbers Apache expects, e.g. $1, $2 etc.) for each URL. They claim PCRE support is "in beta", but it was just what I needed to solve my syntax problems.
http://www.regexplanet.com/advanced/perl/index.html
I'd have simply added a comment to an existing answer but my reputation isn't yet at that level. Hope this helps someone.