htaccess execution order and priority

Question

Can anyone explain to me in what order apache executes .htaccess files residing in different levels of the same path and how the rewrite rules therein are prioritized?

For example, why doesn't the rewrite rule in the first .htaccess below work and is the one in /blog prioritized?

.htaccess in /

RewriteEngine on
RewriteBase /
RewriteRule ^blog offline.html [L]

.htaccess in /blog

RewriteEngine On
RewriteBase /blog/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /blog/index.php [L]

PS: I'm not simply looking for an answer but for a way to understand the apache/mod_rewrite internals ... why is more important to me than how to fix this,

Answer 1

Read the Apache Tutorial: .htaccess, mainly the section "How directives are applied", which states:

The configuration directives found in a .htaccess file are applied to the directory in which the .htaccess file is found, and to all subdirectories thereof. However, it is important to also remember that there may have been .htaccess files in directories higher up. Directives are applied in the order that they are found. Therefore, a .htaccess file in a particular directory may override directives found in .htaccess files found higher up in the directory tree. And those, in turn, may have overridden directives found yet higher up, or in the main server configuration file itself.

But for the special case of mod_rewrite read "Rules inherited from the parent scope are applied after rules specified in the child scope."

Answer 2

You can use RewriteOptions inherit to inherit the rewrite rules of the parent directory. However, the parent directory's rewrite rules will be applied later, as per the documentation on RewriteOptions.