How to check port occupancy in Linux

Linux methods to check port occupancy include: lsof -i method is used to check the occupancy of a certain port; netstat -tunlp|grep method is used to check the process status of the specified port number

We are here When deploying projects, we often encounter the problem of port occupancy, which causes our project to not proceed normally. We need to stop the process that occupies the port before starting a new service to use this port. So how to check the port occupancy in Linux? Well, I will give you a detailed introduction in the article. I hope it will be helpful to you

[Recommended courses: Linux tutorial】

The methods to check the port occupancy are:

Method 1: lsof -i:port number

Method 2: netstat -tunlp|grep port number

##lsof -i:port number

lsof -i is used to display processes that meet the conditions. lsof (list open files) is a tool that lists open files in the current system. Use the root user to execute the lsof -i command

lsof -i: The port number is used to check the occupancy of a certain port, such as checking the usage of port 8000, lsof -i:8000

# lsof -i:8000COMMAND   PID USER   FD   TYPE  DEVICE SIZE/OFF NODE NAME
lwfs    22065 root    6u  IPv4 4395053      0t0  TCP *:irdmi (LISTEN)

pass From the above we can see that port 8000 has been occupied by the lightweight file system forwarding service lwfs

netstat -tunlp|grep port number

netstat -tunlp is mainly used for display Tcp, udp ports and processes and other related information.

netstat -tunlp|grep port is generally used to check the process status of the specified port number. For example, to check the status of port 8000, we can use the following command to check the

netstat -tunlp |grep 8000

# netstat -tunlp 
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address               Foreign Address             State       PID/Program name   
tcp        0      0 0.0.0.0:111                 0.0.0.0:*                   LISTEN      4814/rpcbind        
tcp        0      0 0.0.0.0:5908                0.0.0.0:*                   LISTEN      25492/qemu-kvm      
tcp        0      0 0.0.0.0:6996                0.0.0.0:*                   LISTEN      22065/lwfs          
tcp        0      0 192.168.122.1:53            0.0.0.0:*                   LISTEN      38296/dnsmasq       
tcp        0      0 0.0.0.0:22                  0.0.0.0:*                   LISTEN      5278/sshd           
tcp        0      0 127.0.0.1:631               0.0.0.0:*                   LISTEN      5013/cupsd          
tcp        0      0 127.0.0.1:25                0.0.0.0:*                   LISTEN      5962/master         
tcp        0      0 0.0.0.0:8666                0.0.0.0:*                   LISTEN      44868/lwfs          
tcp        0      0 0.0.0.0:8000                0.0.0.0:*                   LISTEN      22065/lwfs

parameters. Meaning

-T (TCP) indicates that only the options related to TCP are displayed

u ((UDP) indicate only UDP-related options

-n means rejecting Display aliases, all numbers that can be displayed are converted into numbers

-l means only the service status listed in Listen (listening)

-p means display the name of the program that establishes the relevant link

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