kill and signal types in Linux CLI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the kill command do in Linux?

The kill command sends a signal to a process, usually to stop or control it. It can ask a process to stop gently or force it to quit.

beginner

What is the difference between SIGTERM and SIGKILL signals?

SIGTERM politely asks a process to stop, allowing it to clean up. SIGKILL forces the process to stop immediately without cleanup.

beginner

How do you send a SIGINT signal using the kill command?

Use kill -2 <pid> or kill -SIGINT <pid>. SIGINT is like pressing Ctrl+C to interrupt a process.

beginner

What signal number is usually used to force kill a process?

Signal number 9 (SIGKILL) is used to force kill a process immediately.

beginner

Why should you prefer SIGTERM over SIGKILL when stopping a process?

SIGTERM lets the process close files and save data safely. SIGKILL stops it instantly, which might cause data loss.

Which signal number corresponds to SIGKILL?

A 9

B 15

C 2

D 1

SIGKILL is signal number 9, used to forcefully stop a process.

What does the kill -15 <pid> command do?

A Sends SIGHUP to reload the process

B Sends SIGKILL to force stop the process

C Sends SIGINT to interrupt the process

D Sends SIGTERM to politely stop the process

kill -15 sends SIGTERM, which politely asks the process to stop.

Which signal is sent when you press Ctrl+C in the terminal?

A SIGTERM

B SIGINT

C SIGKILL

D SIGSTOP

Ctrl+C sends SIGINT to interrupt the running process.

If a process ignores SIGTERM, which signal should you use next?

A SIGKILL

B SIGINT

C SIGHUP

D SIGSTOP

If SIGTERM is ignored, SIGKILL (signal 9) forces the process to stop.

What is the purpose of the SIGHUP signal?

A Terminate the process immediately

B Pause the process

C Reload configuration or restart the process

D Ignore the process

SIGHUP usually tells a process to reload its configuration or restart.

Explain how the kill command works and name three common signals it can send.

Think about how you stop or control a process using signals.

Describe the difference between SIGTERM and SIGKILL and why you might choose one over the other.

Consider what happens to a process when it receives each signal.