对www.example.com/* 的任何请求都必须重定向到www.example.com/blog/*
如果没有www. 前缀，添加它。
重要的是，如果存在任何与请求 URI 匹配的目录，请不要重定向。
例子：
(www.)example.com/<request> -> www.example.com/blog/<request> 除了<request> === <dirname>
根据上述 3 个条件，我如何编写 .htaccess？请帮忙！ 谢谢 ;-)
【问题讨论】：
这应该可以满足您的要求。我还添加了“如果此文件存在则不要重定向”，因为我不确定现有目录中有什么。如果你不想要它，你可以尝试通过取出第二个RewriteCond 来删除它，但我认为这在某种程度上可能是必要的。
RewriteEngine On
# Check if the requested path is not a real file or a
# real directory
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
# If the current request doesn't start with "blog", and
# it's not a real file or directory based on the above
# conditions, add "blog" to the front of the request, and
# mark an environment variable that indicates we'll need
# to redirect
RewriteRule !^blog blog%{REQUEST_URI} [E=CHANGED:TRUE]
# Check if the host doesn't start with "www.", or if we've
# marked the change variable above, since in either of those
# cases we need to perform a redirection (We do it this way,
# since we'll at most send one redirect back to the client,
# instead of the potential two we might send if we didn't
# combine the checks)
RewriteCond %{HTTP_HOST} !^www\. [OR]
RewriteCond %{ENV:CHANGED} =TRUE
# Capture the non-"www." part of the host, regardless of
# whether or not the "www." is there
RewriteCond %{HTTP_HOST} ^(www\.)?(.*)$
# Redirect anything to the corrected URL, using the
# backreference from the above condition, and the entirety of
# the requested path (possibly modified by the above RewriteRule)
RewriteRule ^.*$ http://www.%2/$0 [R=301,L]
【讨论】：