How to run multiple nginx master processes

[Nuno Magalhães]

It seems to be more OS-specific than nginx-specific, have you asked in
the Ubuntu forums? Why would you want to run two masters?!

Unless nginx does a check to see if another nginx is running (by .pid
file?, so at least that you'd have to change in the script), i guess
you should be safe using two different server configuration files
(i.e. different listening ports and domains).

HTH
Nuno

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