Question:

I want: all links which not contained filename (not .html, .jpg, .png, .css) redirect with state 301 to directory, for example: <a href="http://mysite.com/article" rel="nofollow">http://mysite.com/article</a> -> <a href="http://mysite.com/article/" rel="nofollow">http://mysite.com/article/</a> But <a href="http://mysite.com/article/article-15.html" rel="nofollow">http://mysite.com/article/article-15.html</a> not redirects. What regulat expression I must write to .htaccess for adding slash to virtual directories?

I think the following might work:

RewriteEngine on RewriteCond %{REQUEST_URI} ^/[^\.]+[^/]$ RewriteRule ^(.*)$ http://%{HTTP_HOST}/$1/ [R=301,L]

When it comes to mod_rewrite I can never be sure without testing though...

Clarification needed:

Given the url: <a href="http://server/path/file" rel="nofollow">http://server/path/file</a>

Does that get redirected to: <a href="http://server/path/" rel="nofollow">http://server/path/</a>

Or does it get redirected to: <a href="http://server/path/file/" rel="nofollow">http://server/path/file/</a>

As in: Do you want the redirects to go to the parent path, or do you just want to add a slash and assume directory out of the current path?

MB's RewriteRule above will fail on paths like /a because it needs to match at least two characters after the slash. Moreover it only matches on top directory URLs.

RewriteRule ^(([^\/]+\/)*[^\/\.]+)$ http://%{HTTP_HOST}/$1/ [R=301,L]

Is the purpose of this to reduce history pollution/false negatives?