You might have the domain domain1.com which should redirect visitors to domain2.com. You could set up a virtual host, pointing to /path where an index.php file resides which forwards the user, e.g. with:
<?php
header("Location: http://domain2.com");
?>
The easier way is to create a virtual host, e.g. by creating /etc/apache2/sites-available/domainForwarding with the following content:
<VirtualHost *:80>
ServerName domain1.com
ServerAlias w.domain1.com
ServerAlias ww.domain1.com
ServerAlias www.domain1.com
ServerAlias wwww.domain1.com
ServerAdmin admin@domain1.com
#may be you want some logging: (uncomment he next two lines)
#ErrorLog /var/www/domainForwarding/logs/error.log
#CustomLog /var/www/domainForwarding/logs/access.log common
Options -Indexes
RewriteEngine On
RewriteRule ^.*$ http://www.domain2.com [R,L]
</VirtualHost>
This makes mod_rewrite (which must be enabled) to forward the request whithout the need for additional files.
Note: run a2ensite domainForwarding to enable the site and /etc/init.d/apache2 reload to update the apache’s configuration.