比较好用的linux命令

1、机器的对外IP:curl cip.cc

2、查看机器上两个ip的通信情况：sudo tcpdump host xxxxx and dst yyyy 查看从xxx发向yyy的数据包情况

3、dump堆内存：jmap -dump:format=b,file=1.dump 30190

查看堆中对象：jmap -histo:live 30190 > 30190.dump

jstat -gcutil 2531 2s 3（每隔2s共查看3次堆的情况）

4、查看线程占用的端口的情况

netstat -nap|grep 进程号

public static void main(String[] args) throws SocketException {
    System.out.println("端口：" + DialingRobotUtils.isPortAvailable(8080));
    DatagramSocket socket = new DatagramSocket(8080);
    System.out.println(socket.isClosed());
    socket.setSoTimeout(100);
    System.out.println("端口：" + DialingRobotUtils.isPortAvailable(8080));
    try {
        byte[] data = {};
        DatagramPacket packet = new DatagramPacket(data, 0);
        socket.receive(packet);
    } catch (IOException e) {
        socket.close();
        e.printStackTrace();
    }
    System.out.println("端口：" + DialingRobotUtils.isPortAvailable(8080));
    System.out.println(socket.isClosed());

}

 netstat -tunlp|grep 12411

netstat -nap | grep

------------------------

查看当前目录的各个文件夹的内存占用情况

du --max-depth=1 -h 

https://www.cnblogs.com/flyingeagle/articles/9219106.html

------------------------------------------------------

tcpdump抓包信息

sudo tcpdump -i eth0 -vnn dst host  10.32.0.62  and dst port 20147 -w  1.pcap