Apache httpd/mod rewrite

Syntax

The Apache manual says:

• RewriteRule <Pattern> <Substitution> [<flags>]
• RewriteCond <TestString> <CondPattern> [<flags>]
• RewriteBase <URL-path>

I think I still don't really understand RewriteBase. Apparently it does need to refer to a path that actually exists, rather than a mapped path. If the path doesn't exist, Apache will log a "core:alert" error saying "RewriteBase: argument is not a valid URL".

RewriteRule

Arguments:

• Pattern is a perl compatible regular expression, matched against:
  • if VirtualHost context: the part of the URL after the hostname and port, and before the query string (e.g. "/app1/index.html").
  • if per-directory context (Directory and .htaccess): the partial path to the Directory or .htaccess file
    • e.g. a request of "/app1/index.html" may result in comparison against "app1/index.html" or "index.html" depending on where the RewriteRule is defined.
    • The directory path where the rule is defined is stripped from the currently mapped filesystem path before comparison (up to and including a trailing slash). The net result of this per-directory prefix stripping is that rules in this context only match against the portion of the currently mapped filesystem path "below" where the rule is defined.
• Substitution may be:
  • URL-path: A DocumentRoot-relative path to the intended target
  • Absolute-URL: if the hostname matches the current host, the scheme and hostname are stripped out and the resulting path is treated as a URL-path. Otherwise, an external redirect is performed.
  • filesystem-path (only in VirtualHost)

Official example:

• RewriteRule ^(.+) /other/archive/$1 [R]