我的服务器环境：ubuntu 14 lts

按照这里(https://www.drupal.org/node/1248790)安装了pear及drush

版本：

pear:1.9.4

drush 6.2.0

drupal 7.34

-------------------问题：----------------------------

root身份链接ssh登入到服务器，进入到drupal网站所在目录下，执行drush up后，提示错误：

root@li796-61:/home/admin/web/domain.com# drush update

The drush command 'update' could not be found.  Run `drush cache-clear drush` to clear the commandfile cache [error]

if you have installed new extensions.

A Drupal installation directory could not be found                                                           [error]

root@li796-61:/home/admin/web/domain.com# drush up

Command pm-update needs a higher bootstrap level to run - you will need to invoke drush from a more          [error]

functional Drupal environment to run this command.

Command pm-update needs the following modules installed/enabled to run: update.                              [error]

The drush command 'up' could not be executed.                                                                [error]

A Drupal installation directory could not be found                                                           [error]

root@li796-61:/home/admin/web/domain.com#