使用shell腳本寫(xiě)一個(gè)守護(hù)進(jìn)程，監(jiān)聽(tīng)3003端口，是否有被使用，若沒(méi)有，則開(kāi)啟

#!/bin/sh
cmd=$1
port=3003

if [ -n "$cmd" ]
then
   # 守護(hù)進(jìn)程[ nohup sh run.sh 1 & ]
    while true
    do
        sleep 3;
        
        # 根據(jù)端口號(hào)查詢(xún)對(duì)應(yīng)的pid
        pid=$(netstat -nlp|grep :$port|awk '{print $7}'|awk -F"/" '{ print $1 }')

        # 如果pid不存在，則啟動(dòng)進(jìn)程
        if [ ! -n  "$pid"  ];then
            # echo "開(kāi)啟npm run start"
            nohup npm run start > /var/log/web/user.log 2>&1 & continue
        fi
        # echo '進(jìn)程守護(hù)中......'
    done
else
    # 重啟進(jìn)程[ sh run.sh]
    # 根據(jù)端口號(hào)查詢(xún)對(duì)應(yīng)的pid
    pid=$(netstat -nlp|grep :$port|awk '{print $7}'|awk -F"/" '{ print $1 }')

    #殺掉對(duì)應(yīng)的進(jìn)程，如果pid不存在，則不執(zhí)行
    if [  -n  "$pid"  ];then
        kill  -9  $pid
        echo "殺掉已有進(jìn)程ID: ${pid}"
        echo "重新執(zhí)行npm run start..."
        nohup npm run start > /var/log/web/user.log 2>&1 & exit
    else
        echo "開(kāi)啟npm run start"
        nohup npm run start > /var/log/web/user.log 2>&1 & exit
    fi
fi