"nginx -s [signal]"
$nginx -s stop // fast shutdown
$nginx -s quit // graceful shutdown
$nginx -s reload // reloading the configuration files
$nginx -s reopen // reopen the log files
//kill nginx process
$ ps -ax | grep nginx
21074 ?? 0:00.00 nginx: master process nginx
21075 ?? 0:00.00 nginx: worker process
21123 ttys000 0:00.01 grep nginx
$kill -s QUIT 21074
(kill master process)