3.4 Printing Aggregations

By default, multiple aggregations are displayed in the order in which they are introduced in the D program. You can override this behavior by using the printa function to print the aggregations. The printa function also enables you to precisely format the aggregation data by using a format string, as described in Chapter 6, Output Formatting.

If an aggregation is not formatted with a printa statement in your D program, the dtrace command snapshots the aggregation data and prints the results after tracing has completed, using the default aggregation format. If a given aggregation is formatted with a printa statement, the default behavior is disabled. You can achieve equivalent results by adding the printa(@aggregation-name) statement to an END probe clause in your program. The default output format for the avg, count, min, max, and sum aggregating functions displays an integer decimal value corresponding to the aggregated value for each tuple. The default output format for the quantize, lquantize, and llquantize aggregating functions displays an ASCII table with the results. Aggregation tuples are printed as though trace had been applied to each tuple element.