Tips for debugging .htaccess rewrite rules

Question

Many posters have problems debugging their RewriteRule and RewriteCond statements within their .htaccess files. Most of these are using a shar

Answer 1

Set environment variables and use headers to receive them:

You can create new environment variables with RewriteRule lines, as mentioned by OP:

RewriteRule ^(.*) - [E=TEST0:%{DOCUMENT_ROOT}/blog/html_cache/$1.html]

But if you can't get a server-side script to work, how can you then read this environment variable? One solution is to set a header:

Header set TEST_FOOBAR "%{REDIRECT_TEST0}e"

The value accepts format specifiers, including the %{NAME}e specifier for environment variables (don't forget the lowercase e). Sometimes, you'll need to add the REDIRECT_ prefix, but I haven't worked out when the prefix gets added and when it doesn't.