All DD routines (except the monitor programs) do not print any status or information to stdout or stderr. They instead write the information into a string and invoke a macro, called dd_log.The syntax is dd_log(int info_id, char *msg), where info_id is an identifier for the string message. The currently supported info_id' s are DD_INFO and DD_ERROR.
The macro dd_log currently simply prints the string to stdout or stderr (depending whether info_id is DD_INFO or DD_ERROR.
This behaviour can of course be changed by simply changing this macro dd_log, e.g. popping up a window displaying the information, a feature that might be desirable in a distributed system. The macro is defined in the header file dd_log.h
As an example you can study the integration of the message system of the PHENIX experiment, which is included in the compilation in the Makefile when the variable PHENIX is defined (source code file dd_phenix_msg.cc).
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