you need to install gdb (GNU Debugger)
You should get something like "Binary file mem_086cb000 matches
". Open this file in editor, search for config (e.g. "worker_connections" directive), copy&paste. Profit!
Update: This method isn't entirely reliable. It's based on assumption that nginx process will read configuration and don't overwrite/reuse this memory area later. Master nginx process gives us best chances for that I guess.
Just used this in 2021 with latest nginx and worked. (you may need to do something like piping
cat <mem_7f7777e77000> > file_to_read_with_vi
and then use vi to read that new file. For some reason my text editor would only show raw hex /octals when trying to read these. Not sure if just how I have it set up or missed something. In any case saved me. Thank you.