CKEditor is very helpful in editing the pages and contents in Drupal. The following commands will install this powerful editor in your drupal project with ease.
First download the module with this command.
drush dl ckeditor
Now enable the module.
drush en -y ckeditor
Now download the actual library.
drush ckeditor-download
Now flush your cache.
drush cc all
The above steps will install the editor. To configure it you can go to the CKEditor settings and input profiles.