Constructs and writes kernel messages.
The uprintfd daemon retrieves, converts, formats, and writes kernel messages to processes' controlling terminals. Kernel messages are submitted through the NLuprintf and uprintf kernel services. Because the uprintfd daemon never exits, it should be run only once.
The NLuprintf kernel service and uprintf kernel service.
The Input and Output Handling Programmer's Overview in AIX General Programming Concepts: Writing and Debugging Programs.