Nagios provides a very powerful feature named adaptive monitoring that allows the modification of various check-related parameters on the fly. This is done by sending a command to the Nagios external command pipe.

The first thing that can be changed on the fly is the command to be executed by Nagios, along with the attributes that will be passed to it—an equivalent of the check_command directive in the object definition. In order to do that, we can use the CHANGE_HOST_CHECK_COMMAND or CHANGE_SVC_CHECK_COMMAND command. These require the hostname or the hostname and service description, and the check command as arguments.

This can be used to change how hosts or services are checked, or to only modify parameters that are passed to the check commands; for example, a check for ping latency can be modified based on whether a primary or a backup connection is used. An example to change a check command of a service, which changes the command and its specified parameters,...