假设有域名domain.com，已经泛解析子域名*.domain.com到该主机的ip，web根目录为/var/www/，
在访问a.domain.com时，能自动绑定/var/www/a/目录，访问b.domain.com时，能自动绑定/var/www/b/目录
1、分别手动建立相应的virtualhost
主机配置文件vhost.conf
以及/var/www/.htaccess文件
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} ^(.*)\.domain\.com$
RewriteCond %{REQUEST_URL} !^/%1/
RewriteRule ^(.*)$ %1/$1
</IfModule>
此时不论以哪个域名访问，都会返回服务器内部错误
如果把RewriteCond %{REQUEST_URL} !^/%1/这行配置中的%1替换成具体的字符串，如a，这样的话，能够实现a.domain.com绑定到/var/www/a/目录，但是其他域名依然是/var/www/目录
2、任意主机名的虚拟主机
RewriteEngine on RewriteMap lowercase int:tolower RewriteCond "${lowercase:%{HTTP_HOST}}" "^www\.([^.]+)\.example\.com$" RewriteRule "^(.*)" "/home/%1/www$1"
3、vhost_alias模块实现通配子域名
主机配置文件vhost.conf
<VirtualHost *:80> ServerAdmin webmaster@localhost ServerName test.loc ServerAlias *.test.loc # This will be the wildcarded document root. Any folder you create in /var/www/test will be automatically a subdomain name. VirtualDocumentRoot /var/www/test/%-3 # For symlinking your projects and htaccesses to work <Directory /> Options FollowSymLinks AllowOverride All </Directory> ErrorLog /var/log/apache2/vhosts-error.log # Possible values include: debug, info, notice, warn, error, crit, # alert, emerg. LogLevel warn CustomLog /var/log/apache2/vhosts-access.log combined </VirtualHost>
https://inchoo.net/magento/how-to-setup-semiautomatic-per-folder-wildcard-subdomains-on-your-local-linux-based-development-computer/
https://httpd.apache.org/docs/2.4/rewrite/vhosts.html