How to get information from a demon in C?

Question

C++ / C#

Wrote a demon in C. How can I get work statistics from it? About 10 indicators. Further, these indicators will be displayed in Cacti.
The program is relatively small, so I don't want to bother with embedding snmp agents or sockets. I'm considering the option to periodically write statistics to a file, but maybe there is a more elegant solution?

Answer 1

Let's say through the POSIX message queue: send, for example, SIGUSR1, then read from the queue.
Read Stevens "UNIX: Interaction of Processes".

Answer 2

Well, if not to a socket and not to a file (which is basically the same thing), then it remains just printing to stderrr, stdout (which are basically the same files)