Generic htaccess redirect www to non-www

Question

RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} ^www\.(.*)$ [NC]
RewriteRule ^(.*)$ https://%1/$1 [R=301,L]

Same as Michael's except this one works :P

But if we need to do this for separate http and https:

RewriteCond %{HTTPS} off
RewriteCond %{HTTP_HOST} ^www\.(.*)$ [NC]
RewriteRule ^(.*)$ http://%1/$1 [R=301,L]

RewriteCond %{HTTPS} on
RewriteCond %{HTTP_HOST} ^www\.(.*)$ [NC]
RewriteRule ^(.*)$ https://%1/$1 [R=301,L]

Redirect non-www to www (both: http + https)

RewriteCond %{HTTPS} off
RewriteCond %{HTTP_HOST} !^www\.(.*)$ [NC]
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]

RewriteCond %{HTTPS} on
RewriteCond %{HTTP_HOST} !^www\.(.*)$ [NC]
RewriteRule ^(.*)$ https://www.%{HTTP_HOST}/$1 [R=301,L]

If you want to do this in the httpd.conf file, you can do it without mod_rewrite (and apparently it's better for performance).

<VirtualHost *>
  ServerName www.example.com
  Redirect 301 / http://example.com/
</VirtualHost>

I got that answer here: https://serverfault.com/questions/120488/redirect-url-within-apache-virtualhost/120507#120507

Here are the rules to redirect a www URL to no-www:

#########################
# redirect www to no-www
#########################

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

Here are the rules to redirect a no-www URL to www:

#########################
# redirect no-www to www
#########################

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

Note that I used NE flag to prevent apache from escaping the query string. Without this flag, apache will change the requested URL http://www.example.com/?foo%20bar to http://www.example.com/?foo%2250bar

RewriteCond %{HTTP_HOST} ^www\.(.*)$ [NC]
RewriteRule ^/(.*)$ https://%1/$1 [R]

The RewriteCond captures everything in the HTTP_HOST variable after the www. and saves it in %1.

The RewriteRule captures the URL without the leading / and saves it in $1.

Complete Generic WWW handler, http/https

I didn't see a complete answer. I use this to handle WWW inclusion.

1. Generic. Doesn't require domain info.
2. Forces WWW on primary domain: www.domain.com
3. Removes WWW on subdomains: sub.domain.com
4. Preserves HTTP/HTTPS status.
5. Allows individual cookies for domain / sub-domains

Please let me know how this works or if I left a loophole.

RewriteEngine On
RewriteBase /

# Force WWW. when no subdomain in host
RewriteCond %{HTTP_HOST} ^[^.]+\.[^.]+$ [NC]
RewriteCond %{HTTPS}s ^on(s)|off [NC]
RewriteRule ^ http%1://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

# Remove WWW. when subdomain(s) in host     
RewriteCond %{HTTP_HOST} ^www\. [NC]
RewriteCond %{HTTPS}s ^on(s)|off [NC]
RewriteCond http%1://%{HTTP_HOST} ^(https?://)(www\.)(.+\.)(.+\.)(.+)$ [NC]
RewriteRule ^ %1%3%4%5%{REQUEST_URI} [R=301,L]