Since the massive rise of smartphones and tablets like the iPhone, iPad, Android phones and tablets, BlackBerries, etc. you might have considered creating a mobile version of your web site. This tutorial explains how to configure Apache to serve the mobile version of your web site if the visitor uses a mobile device, and the normal version if the visitor uses a normal desktop PC. This can be achieved with Apache’s rewrite module.
In this tutorial, “normal” web site is accessible under http://www.example.com and http://example.com, while my mobile site is called http://m.example.com.
Step 1: Enabling mod_rewrite
First you have to make sure that the Apache module mod_rewrite is enabled. On Debian/Ubuntu, you can enable it like this:
a2enmod rewrite
Restart Apache afterwards – for Debian/Ubuntu, the command is:
/etc/init.d/apache2 restart
Step 2: Configuring Apache To Allow Rewrite Rules In .htaccess Files
My “normal” web site www.example.com or example.com has the vhost configuration file /etc/apache2/sites-available/www.example.com.vhost and the document root /var/www/www.example.com/web.
My mobile site m.example.com has the vhost configuration file /etc/apache2/sites-available/m.example.com.vhost and the document root /var/www/www.example.com/mobile.
I want to place the rewrite rules for each site in an .htaccess file (although it is also possible to place the rewrite rules directly in the vhost configuration file). Therefore I must first modify our vhost configurations so that both .htaccess files are allowed to contain rewrite directives. We can do this with the line AllowOverride All (which allows .htaccess to override all settings in the vhost configuration):
vi /etc/apache2/sites-available/www.example.com.vhost
[...]
AllowOverride All
[...]
vi /etc/apache2/sites-available/m.example.com.vhost
[...]
AllowOverride All
[...]
Restart Apache afterwards:
/etc/init.d/apache2 restart
Step 3: Creating Rewrite Rules
Now let’s create the rewrite rules for the “normal” web site www.example.com/example.com that will redirect all users of mobile devices to the mobile version m.example.com – I focus on the relevant devices/user agents here which are Android, Blackberry, googlebot-mobile (Google’s mobile search bot), IE Mobile, iPad, iPhone, iPod, Opera Mobile, PalmOS, and WebOS.
The /var/www/www.example.com/web/.htaccess file looks as follows:
vi /var/www/www.example.com/web/.htaccess
RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} "android|blackberry|googlebot-mobile|iemobile|ipad|iphone|ipod|opera mobile|palmos|webos" [NC]
RewriteRule ^$ http://m.example.com/ [L,R=302]
For our mobile web site m.example.com, the rewrite rules that redirect all users that don’t use a mobile device to our “normal” web site www.example.com/example.com look as follows – I’ve simply negated the RewriteCond condition from the previous .htaccess file:
vi /var/www/www.example.com/mobile/.htaccess
RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} "!(android|blackberry|googlebot-mobile|iemobile|ipad|iphone|ipod|opera mobile|palmos|webos)" [NC]
RewriteRule ^$ http://www.example.com/ [L,R=302]
That’s it! Now you can do some testing, e.g. visit m.example.com with a normal desktop browser:
If all goes well, you should be redirected to www.example.com:
Now test with a mobile device (I use an Android phone here) and go to www.example.com:
You should be redirected to m.example.com:
