During my second semester as a CIT major one of the things we had to get used to doing was learning the different debug and show commands available to us in different privilege modes on the routers. One thing that made all that a little bit easier was the do command.

The command can be used in privilege mode to force the router to do some commands otherwise restricted to EXEC mode.


ROUTER1(config)$sh run                 
                  ^
% Invalid input detected at ‘^’ marker.

ROUTER1(config)do sh run

Building configuration. . .

So as you can see no hoping back and forth between config modes. The only limit my research yields to do command to is using it to change the current config mode itself (it cannot be used to initiate the config t command.)