Drush was installed using PEAR. Drush by default was installed in /usr/share/php/drush folder. I am trying to run drush from my site root.

Could someone please help to resolve this error?

 

root@devdrupal:/var/www/drupal# drush pml
Command pm-list needs a higher bootstrap level to run - you will need to    [error]
invoke drush from a more functional Drupal environment to run this
command.
The drush command 'pml' could not be executed.                              [error]
       

                                                                     [error]

 

Drush was attempting to connect to:
 Drupal version         :  7.23                 
 Site URI               :  http://default       
 Database driver        :  mysql                
 Database username      :  drupaluser           
 Database name          :  acquia_drupal        
 Default theme          :  garland              
 Administration theme   :  garland              
 PHP executable         :  /usr/bin/php         
 PHP configuration      :  /etc/php5/cli/php.ini
 PHP OS                 :  Linux                
 Drush version          :  6.2.0                
 Drush configuration    :                       
 Drush alias files      :                       
 Drupal root            :  /var/www/drupal      
 Site path              :  sites/default        
 File directory path    :  sites/default/files