kill — terminate processes

💬 "kill command"

• Concept: Sends a signal to a running process to terminate it or make it reread its configuration. The target is specified by PID.
• Output structure: On success, it prints nothing. If the PID does not exist, it returns the <code>No such process</code> error.
• Practical recommendation: First terminate gracefully with the default <code>kill PID</code>(SIGTERM), and use <code>kill -9</code> only when there is no response.
• -15 (SIGTERM): This is the default signal. It asks the process to perform cleanup and exit.
• -9 (SIGKILL): This is a forced termination. It ends the process immediately without cleanup, so use it only as a last resort.

Three essential command combinations

• kill PID — request a normal termination with the default (SIGTERM)
• kill -9 PID — force termination when there is no response
• kill -l — list available signals

Here are some additional options worth knowing.

• kill -HUP PID — make the process reread its configuration without terminating it
• Before using kill, verify that the target is correct with ps -p PID -o pid,cmd

💬 "Please give me one brief real-world example"

Scenario: This is the process of cleaning up an unresponsive web server process step by step.

Step 1: Verify the target

Check that the PID and command are correct.

ps -p 4821 -o pid,user,cmd

Step 2: Request a graceful termination

Request termination with the default signal.

kill 4821

Step 3: Force termination

If it is still running, terminate it forcefully.

kill -9 4821

Real execution screenshot

This is an example screen showing a process being terminated and verified with kill.

!kill command execution result: confirm PID and then send termination signal

A real production server

Source (HTML): https://games.aidebatehub.com/programs/linux/services/kill.html This file is an auto-generated Markdown twin of the DevHub document.