How to redirect correctly with htaccess?

Question

htaccess

How to record correctly so that when entering without www there is a redirect, such a record only if we enter the site from www works.

RewriteCond %{HTTP_HOST} ^www\.site\.ru [NC]
RewriteCond %{HTTP_USER_AGENT} "android|blackberry|iphone|ipod|iemobile|opera mobile|palmos|webos|googlebot-mobile" [NC]
RewriteRule ^(.*)$ http://m.site.ru/$1 [L,R=302]

Answer 1

If you need both options (with www and without).

RewriteCond %{HTTP_HOST} ^(www\.)?site\.ru$ [NC]
RewriteCond %{HTTP_USER_AGENT} "android|blackberry|iphone|ipod|iemobile|opera mobile|palmos|webos|googlebot-mobile" [NC]
RewriteRule ^(.*)$ http://m.site.ru/$1 [L,R=302]

If you need a rule only for without www.

RewriteCond %{HTTP_HOST} ^site\.ru$ [NC]
RewriteCond %{HTTP_USER_AGENT} "android|blackberry|iphone|ipod|iemobile|opera mobile|palmos|webos|googlebot-mobile" [NC]
RewriteRule ^(.*)$ http://m.site.ru/$1 [L,R=302]