Nginx
Test the nginx config
$ sudo nginx -t
$ sudo nginx -t -c /etc/nginx/nginx.conf
nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful
Reload Nginx if the config test was successful
sudo /etc/init.d/nginx configtest && sudo /etc/init.d/nginx reload
alias ngx_config_reload='sudo /etc/init.d/nginx configtest && sudo /etc/init.d/nginx reload'
Check which ports listen e.g. nginx(port 80)
sudo lsof -nP -i | grep LISTEN
Get the amount of cores you have on your setup
grep processor /proc/cpuinfo | wc -l
Show the maximum number of open file descriptors
ulimit -n