This is how!
Edit a .conf (in my case I have a redirects.conf) for this kind of redirects….
nano /etc/apache2/sites-enabled/redirects.conf
And add the following lines…
<VirtualHost *:80>
ServerName example.com
Redirect permanent / http://www.example.com/
</VirtualHost>
and naturally restart apache! 😉
service apache2 restart