How to Find Process by Port on Linux Quickly

To find the process using a specific port on Linux, use the command lsof -i :PORT or netstat -tulpn | grep PORT. Replace PORT with the port number you want to check. These commands show the process ID and name listening on that port.

Syntax

The main commands to find a process by port are:

• lsof -i :PORT: Lists open files related to the specified port.
• netstat -tulpn | grep PORT: Shows network connections with process info filtered by port.

Replace PORT with the actual port number you want to check.

bash

lsof -i :PORT

netstat -tulpn | grep PORT

Example

This example finds the process using port 8080. It shows the process ID and name listening on that port.

bash

lsof -i :8080

Output

COMMAND   PID USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
python3  1234 user   10u  IPv4  12345      0t0  TCP *:http-alt (LISTEN)

Common Pitfalls

Common mistakes include:

• Not running commands with sudo when required, which may hide some processes.
• Using the wrong port number or forgetting to replace PORT in the command.
• Using netstat on systems where it is deprecated; prefer ss or lsof.

Always check if you have the right permissions and the correct port number.

bash

netstat -tulpn | grep 80
# Might show no output if not run with sudo

sudo netstat -tulpn | grep 80
# Correct way to see processes on port 80

Quick Reference

Command	Description
lsof -i :PORT	List process using the specified port
netstat -tulpn | grep PORT	Show listening processes on the port (may need sudo)
ss -tulpn | grep PORT	Modern alternative to netstat to find process by port

Key Takeaways

Use lsof -i :PORT to quickly find the process using a port.

Run commands with sudo to see all processes if needed.

Replace PORT with the actual port number you want to check.

On newer systems, prefer ss over netstat for network info.

Check permissions and command syntax carefully to avoid missing results.