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

This starts with the HTTP_HOST variable, which contains just the domain name portion of the incoming URL (example.com). Assuming the domain name does not contain a www. and matches your domain name exactly, then the RewriteRule comes into play. The pattern ^(.*)$ will match everything in the REQUEST_URI, which is the resource requested in the HTTP request (foo/blah/index.html). It stores this in a back reference, which is then used to rewrite the URL with the new domain name (one that starts with www).

[NC]表示不区分大小写的模式匹配，[R=301]表示使用代码301进行外部重定向(资源永久移动)，[L]停止所有进一步重写，并立即重定向。

我在WP Multisite上有一个类似的任务，其中重定向规则必须是通用的(对于我添加到网络中的任何给定域)。我首先解决了向域(停放的域)添加通配符。注意。com之后。

CNAME * domain.com.

然后我在我的多站点根目录下的.htaccess文件中添加了以下代码行。我想它适用于任何网站。

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

希望这能有所帮助。

ps.如果你想从not www重定向到www，把最后一行改为

RewriteRule ^(.*)$ http://www.%1/$1 [R=301,L]

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

This starts with the HTTP_HOST variable, which contains just the domain name portion of the incoming URL (example.com). Assuming the domain name does not contain a www. and matches your domain name exactly, then the RewriteRule comes into play. The pattern ^(.*)$ will match everything in the REQUEST_URI, which is the resource requested in the HTTP request (foo/blah/index.html). It stores this in a back reference, which is then used to rewrite the URL with the new domain name (one that starts with www).

[NC]表示不区分大小写的模式匹配，[R=301]表示使用代码301进行外部重定向(资源永久移动)，[L]停止所有进一步重写，并立即重定向。

这是我自己网站的配置，工作起来很有魅力。

<IfModule mod_ssl.c>
  <VirtualHost *:443>
    ServerAdmin admin@domain.com

    ServerName www.domain.com
    ServerAlias domain.com

    DocumentRoot /var/www/html/domain

    <Directory /var/www/html/domain/>
      Options FollowSymLinks
      AllowOverride All
      Require all granted
    </Directory>

    # Redirect non-www to www
    RewriteEngine On

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

    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined

    Include /etc/letsencrypt/options-ssl-apache.conf
    SSLCertificateFile /etc/letsencrypt/live/domain.com/fullchain.pem
    SSLCertificateKeyFile /etc/letsencrypt/live/domain.com/privkey.pem
  </VirtualHost>
</IfModule>

要将所有直接发送到域名www的请求重定向到301，您可以使用:

RewriteEngine On

RewriteCond %{HTTP_HOST} !^([^.]+\.[^.]+){2,}$ [NC]
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

这样做的好处是，如果你有任何有效的子域，这将工作。

example.com重定向到www.example.com

没有重定向

没有重定向

如果你正在使用Apache 2.4，不需要启用重写Apache模块，你可以使用这样的东西:

# non-www to www
<If "%{HTTP_HOST} = 'domain.com'">
  Redirect 301 "/" "http://www.domain.com/"
</If>