基于here所写的内容，我能够使用htaccess设置移动设备检测。我添加了从m.example.com重定向回桌面站点的功能，以防用户不使用移动设备访问该站点。另外，我添加了一个环境变量来保存http / https请求：
# Set an environment variable for http/https.
RewriteCond %{HTTPS} =on
RewriteRule ^(.*)$ - [env=ps:https]
RewriteCond %{HTTPS} !=on
RewriteRule ^(.*)$ - [env=ps:http]
# Check if m=1 is set and set cookie 'm' equal to 1.
RewriteCond %{QUERY_STRING} (^|&)m=1(&|$)
RewriteRule ^ - [CO=m:1:example.com]
# Check if m=0 is set and set cookie 'm' equal to 0.
RewriteCond %{QUERY_STRING} (^|&)m=0(&|$)
RewriteRule ^ - [CO=m:0:example.com]
# Cookie can't be set and read in the same request so check.
RewriteCond %{QUERY_STRING} (^|&)m=0(&|$)
RewriteRule ^ - [S=1]
# Check if this looks like a mobile device.
RewriteCond %{HTTP:x-wap-profile} !^$ [OR]
RewriteCond %{HTTP_USER_AGENT} "android|blackberry|ipad|iphone|ipod|iemobile|opera mobile|palmos|webos|googlebot-mobile" [NC,OR]
RewriteCond %{HTTP:Profile} !^$
# Check if we're not already on the mobile site.
RewriteCond %{HTTP_HOST} !^m\.
# Check if cookie is not set to force desktop site.
RewriteCond %{HTTP_COOKIE} !^.*m=0.*$ [NC]
# Now redirect to the mobile site preserving http or https.
RewriteRule ^ %{ENV:ps}://m.example.com%{REQUEST_URI} [R,L]
# Check if this looks like a desktop device.
RewriteCond %{HTTP_USER_AGENT} "!(android|blackberry|ipad|iphone|ipod|iemobile|opera mobile|palmos|webos|googlebot-mobile)" [NC]
# Check if we're on the mobile site.
RewriteCond %{HTTP_HOST} ^m\.
# Check if cookie is not set to force mobile site.
RewriteCond %{HTTP_COOKIE} !^.*m=1.*$ [NC]
# Now redirect to the mobile site preserving http or https.
RewriteRule ^ %{ENV:ps}://example.com%{REQUEST_URI} [R,L]
除了一件事之外，这很好用：当我从桌面设备访问m.example.com/?m=1时，我被重定向到example.com，尽管我应该“留在”m.example.com上。当我再试一次时，我会“留在”m.example.com。似乎第一次没有正确设置和/或读取cookie。
任何想法可能是什么问题？