An important role of the LSOF/NETSTAT command: According to the process check port, according to the port check process

We know, according to Ps-aux | grep xxx is to implement the process name and process number of mutual search, so we just say the process number PID line.
In the example below, the process PID is resident.

    1.  根据进程pid查端口：         lsof -i | grep pid    2.  根据端口port查进程（某次面试还考过）：        lsof  -i:port         3. 根据进程pid查端口：       netstat -nap | grep pid    4.  根据端口port查进程       netstat -nap | grep port

An important role of the LSOF/NETSTAT command: According to the process check port, according to the port check process