How to redirect requests in htaccess?

Question

htaccess

Hello.
Help me figure out how to redirect non-existent urls (by mask) to one existing,
for example, redirect all addresses of the mysite.ru/katalog/* format to
mysite.ru/contacts Need a 301 redirect.
RewriteCond /your/docroot/%{REQUEST_FILENAME} !-f
RewriteRule ^(.+) webserverB.dom/$1 [R=301,L]
CMS Wordpress

Answer 1

If you need to redirect under the condition
if not 404
and then Then .htaccess
will not help you in principle, since you need to get the server response code before redirecting, which means that for any url on the site you will have to get the server response code. which in turn will greatly affect the performance of the site. Therefore, this is not the right option . The easiest way to solve the problem with the condition on 404 is to write rewrites in 404.php already in php, they are written easier and their cycles are less strange. In this case, redirects will only work if the url is not found. Now in your regular season you messed up
firstly the sequence RewriteCond /your/docroot/%{REQUEST_FILENAME} !-f
secondly the variable itself.

RewriteCond %{REQUEST_URI} ^(.*)/dir1/(.*)$ 
# если строка содержит /dir1/ 
RewriteRule ^(.*)$ %1/dir2/%2 [R=301,L] 
#Перенаправить все урлы с начинающиеся с dir1 на dir2 с сохранением дальнейшей структуры URL