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I’m attempting to terminate a process through the command line associated with a specific port on my Ubuntu system.

When I execute the following command, it provides me with the port number:

sudo lsof -t -i:9001

So, my next step is to execute:

sudo kill 'sudo lsof -t -i:9001'

However, I encounter this error message:

ERROR: invalid process ID "lsof -t -i:9001".
Usage:
  kill pid ...              Send SIGTERM to every process listed.
  kill signal pid ...       Send a signal to every process listed.
  kill -s signal pid ...    Send a signal to every process listed.
  kill -l                   List all signal names.
  kill -L                   List all signal names in a nice table.
  kill -l signal            Convert between signal numbers and names.
I also attempted using: sudo kill 'lsof -t -i:9001'

Step 1: Identify the Process

When you need to terminate a process running on a particular port in Ubuntu, the first step is to identify the Process ID (PID) associated with that port. The command lsof (short for “list open files”) can help us with this.

Open your terminal and type the following command, replacing 9001 with the port number you’re interested in:

sudo lsof -t -i:9001

The -t flag tells lsof to output only the PIDs of the processes, and the -i:9001 flag specifies that you want to target processes using the port 9001.

This command will display the PID of the process currently using the specified port.

Step 2: Terminate the Process

Once you have the PID of the process, you can proceed to terminate it using the kill command. The kill command sends signals to processes, allowing you to control their behavior. In this case, we want to stop the process gracefully.

In the terminal, type the following command, replacing <PID> with the actual PID you obtained from the previous step:

sudo kill <PID>

For example, if the PID is 12345, the command would be:

sudo kill 12345

This command sends a default signal (SIGTERM) to the process, asking it to gracefully terminate.

Step 3: Confirm Termination

After terminating the process, it’s a good idea to verify that it has indeed been stopped and the port is no longer in use. You can use the lsof command again, like this:

sudo lsof -i:9001

If the process has been successfully terminated, you won’t see any output. This indicates that the port is now free and available for other uses.

In summary, to terminate a process running on a specific port in Ubuntu:

1. Identify the process using the lsof command:

   sudo lsof -t -i:9001

2. Terminate the process using the kill command and the PID obtained:

   sudo kill <PID>

3. Confirm the termination by checking if the port is free:

   sudo lsof -i:9001

Following these steps will help you gracefully terminate a process that’s using a particular port on your Ubuntu system.

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