Get Drush to run Drupal cron regularly using crontab

Drush can Drupal cron without the need of accessing http://www.yoursite.com/cron.php?cron_key=<key>. This means we can safely remove or redirect cron.php to 404 Not Found in our .htaccess:

RewriteRule cron.php / [R=404,L]

To make our crontab script simple, we will use Drush's site aliases. Example if we are running multiple sites in our server: yoursite1.com, yoursite2.com and yoursite3.com we can assign alias @site1, @site2 and @site3 respectively. To do this: