Auto detect the number of CPU's and set worker_processes

Igor Sysoev igor at
Mon Sep 17 09:55:52 UTC 2012

On Sep 16, 2012, at 3:55 , justin wrote:

> I am trying to get fancy and have `nginx.conf` auto-detect the number of
> CPU's on the server and then set `worker_processes` to that number. Here is
> what I have:
>    worker_processes $(cat /proc/cpuinfo | grep "processor" | sort -u | wc
> -l);
> Unfortunately, that is throwing an error on nginx start. Is it even possible
> to run shell commands from inside nginx configuration files?

You can configure it via command line:
nginx -g "worker_processes `cat /proc/cpuinfo | grep "processor" | sort -u | wc -l`;"

Igor Sysoev

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