运行Drush出错：The following restricted PHP modes have non-empty values

[root@drupal8 ~]# php drush.phar core-status
The following restricted PHP modes have non-empty values:            [error]
disable_functions. This configuration is incompatible with drush. 
Please check your configuration settings in
/usr/local/php/etc/php.ini or in your drush.ini file; see
examples/example.drush.ini for details.
exec() has been disabled for security reasons preflight.inc:398      [warning]
exec() has been disabled for security reasons preflight.inc:443        [warning]
exec() has been disabled for security reasons preflight.inc:398        [warning]
exec() has been disabled for security reasons preflight.inc:398        [warning]
 PHP configuration      :  /usr/local/php/etc/php.ini 
 PHP OS                 :  Linux                      
 Drush script           :  /root/drush.phar           
 Drush version          :  8.1.9                      
 Drush temp directory   :  /tmp                       
 Drush configuration    :                             
 Drush alias files      :     

大神们，这个怎样解决？