www url rewrite not working (Read All Other Threads) - apache

Question

i want to rewrite
example.com to www.example.com
My Code in apache2.conf (Main config file of apache in Linux/ubuntu 32bit ):
try 1:
RewriteEngine On
RewriteCond %{HTTP_HOST} ^example.com [NC]
RewriteRule ^(.*)$ http://www.example.com/$1 [L,R=301]
Restart Apache Code Doesn't Work !
try 2:
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{HTTP_HOST} ^example.com [NC]
RewriteRule ^(.*)$ http://www.example.com/$1 [L,R=301]
</IfModule>
Restart Apache Code Doesn't Work !
try 3:
RewriteEngine On
RewriteCond %{HTTP_HOST} !^www.example.com$ [NC]
RewriteRule ^(.*)$ http://www.example.com/$1 [R=301,L]
Restart Apache Code Doesn't Work !
Loaded Modules in apache displays:
rewrite_module (shared)
How can i solve this ?
And is there any other mod i have to enable(I don't think so).
I have to put this code in some other file ?
It is neccessary/must use .htaccess for url rewriting ?

Answer 1

Your rules are fine.
Make sure the rules are in the virtualhost of the "example.com" domain. If you have no "example.com" vhost, then place the rules in the first vhost container. S
<VirtualHost *:80>
ServerName example.com
....
RewriteEngine On
RewriteCond %{HTTP_HOST} ^example.com [NC]
RewriteRule ^(.*)$ http://www.example.com/$1 [L,R=301]
....
</VirtualHost>
Try putting the rules in a directory container:
<Directory "/var/www/path/of/your/document_root/">
RewriteEngine On
RewriteCond %{HTTP_HOST} ^example.com [NC]
RewriteRule ^(.*)$ http://www.example.com/$1 [L,R=301]
</Directory>