Use the auto-upgrade-option enabled command in the service host submode to configure automatic upgrades.
The following options apply:
?default? Sets the value back to the system default setting.
?directory? Directory where upgrade files are located on the file server.
For more information refer to the following link
http://www.cisco.com/en/US/products/hw/vpndevc/ps4077/products_configuration_guide_chapter09186a008045a95f.html
A leading `/' indicates an absolute path.