Upgrade drupal 6 to drupal 7 with drush

Please note if you are upgrading minor version of drupal-7.21 to drupal-7.22. Then please use

drush pm-update

Prerequisite:

1. If you are upgrading from drupal 6 to drupal 7, you must be on the latest version of drupal 6 release. 2. There is a difference between update and upgrade. 3. You should have a separate directory(target) which will be the act as active drupal root directory.

Main work starts here

Site-upgrade always upgrades from the current Drupal site to an empty Drupal site. You need a site alias to show the target website.

How to create an alias:

 

 cd ~
cd .drush

Create here file named as test.aliases.drushrc.php put following code in it.

$aliases['test'] = array (
'root' => '/path/to/upgraded/drupalroot',
'uri' => 'http://localhost/drupal7',
);  

Final Command

drush site-upgrade @test

That all folks !!!