When make_target determines that it has to perform an action command, it prints the target and action of that rule, on two successive output lines, before calling do_action(). The output of some of the public tests illustrates this, 5.2 Command output and buffering As mentioned, whatever output is produced by executing action commands will appear in the output of a program calling make_target(). Note that since do_action() should not return until an action finishes executing, there will be a definite output order.