How to immediately know if you are logged into the active or standby firewal on ASA

The prompt (introduced in 7.2(1)) command allows you to customize the hostname of the ASA to include dynamic elements.

prompt state will display the state of the firewall.
for example:
lab-dev-01# config t
lab-dev-01 (config)# prompt state 
lab-dev-01/act(config)#


•act—Failover is enabled, and the unit is actively passing traffic.

•stby— Failover is enabled, and the unit is not passing traffic and is in a standby, failed, or other non-active state.

•actNoFailover—Failover is not enabled, and the unit is actively passing traffic.

•stbyNoFailover—Failover is not enabled, and the unit is not passing traffic. This might happen when there is an interface failure above the threshold on the standby unit.