Actions enable your DTrace programs to interact with the system outside of DTrace. The most common actions record data to a DTrace buffer. Other actions are available, such as stopping the current process, raising a specific signal on the current process, or ceasing tracing altogether. Some of these actions are destructive in that they change the system, albeit in a well-defined way. These actions may only be used if destructive actions have been explicitly enabled. By default, data recording actions record data to the principal buffer. For more details on the principal buffer and buffer policies, see Chapter 11, Buffers and Buffering.