Basta acessar a sugestão do desenvolvedor aqui:
If you really want logging to an external process - try using mkfifo(1), but please keep in mind that this will lead to service interruption if your logging process won't be able to cope with load. I would recommend logging to a normal file and using "tail -F /path/to/log | script" instead if you need some log processing.
Veja também: Maneira correta de girar os logs do Nginx