how to change ospf interface cost dynamically

[d tbsky]

hi:
   I have two ospf interfaces between two routers. sometimes I want to
use one of the interfaces to transfer data, and sometimes I want to
use another.

   I think I can change configuration of interface cost and issue bird
reload every time I need to switch interface. but I wonder if there is
smarter way. any possibility I can change some interface parameters by
linux system commands, so bird would change ospf cost dynamically? or
can I tell bird to change interface cost dynamically?

   thanks a lot for suggestion!