How to check if port is in use in Linux

In Linux, you can check if a port is in use using various commands. Here are a few methods:

1. Using netstat: You can use the netstat command to display network connections, routing tables, interface statistics, masquerade connections, and multicast memberships. To check if a port is in use, you can run:

   netstat -tuln | grep <port_number>

For example, to check if port 8080 is in use:

   netstat -tuln | grep 8080

This command will list all listening (-l) TCP (-t) and UDP (-u) sockets along with their numeric addresses (-n) and port numbers.

2. Using lsof: The lsof command lists open files, including network connections. To check if a port is in use, you can run:

   sudo lsof -i :<port_number>

For example, to check if port 8080 is in use:

   sudo lsof -i :8080

This command will list the processes (-i) that are using the specified port.

3. Using ss (socket statistics): ss is another utility to investigate sockets. You can use it to check if a port is in use:

   sudo ss -tuln | grep <port_number>

For example, to check if port 8080 is in use:

   sudo ss -tuln | grep 8080

This command will display listening (-l) TCP (-t) and UDP (-u) sockets with numeric addresses (-n) along with their port numbers.

These commands will help you identify if a particular port is being used by any process on your Linux system. Remember to use sudo or run these commands with appropriate permissions to access all necessary information.