思路：nginx啟動后會有nginx.pid文件在指定位置下，通過判斷該文件是否存在。決定nginx是否已經啟動。

#!/bin/bash

this is my first try to test write a shell to control nginx daemon
History 2015-08-04 masterliu
PATH=/usr/bin/:/usr/local/bin:/bin:/usr/sbin:/usr/local/sbin:/sbin:~/bin
export PATH
this file could be configured in nginx.conf
PIDfile=/usr/local/nginx/logs/nginx.pid
Nginxd=/usr/local/nginx/sbin/nginx
function start(){

    if [ -e $PIDfile ];then

    echo -e "nginx has already started\t\t[OK]" && exit 0

    fi

    $Nginxd &> /dev/null

    if [ $? = 0 ];then

            echo -e "nginx has started\t\t[OK]"

    else

            echo -e " nginx start failed\t\t[FAILED]"

    fi


}
function stop(){

    if [ ! -e $PIDfile ];then

            echo -e "nginx has already stopped\t\t[OK]" && exit 0

    fi

    #killall nginx

     $Nginxd -s stop &> /dev/null

    sleep 2

    if [ ! -e $PIDfile ];then

            echo -e "nginx has stopped\t\t[OK]";

    fi


}
function reload(){

    if [ ! -e $PIDfile ];then

            echo -e "nginx hasn't start\t\t[OK]" && exit 0

    fi

    $Nginxd -s reload && echo -e "nginx has reload\t\t[OK]" && exit 0


}
function status(){

    if [ ! -e $PIDfile ];then

            echo -e " nginx hasn't run\t\t[OK]"

    else

            echo -e " nginx is running\t\t[OK]"

    fi


}
case "$1" in
start)

    start


;;
stop)

    stop


;;
restart)

    stop;

    start;


;;
status)

    status


;;
reload)

    reload


;;
*)

    echo -e "\t start|stop|restart|status|reload\t"


;;
esac
</pre> 

 來自：http://my.oschina.net/lsfop/blog/488185