Overview

kill sends signals to processes. It is used for graceful shutdowns, reloads, or forced termination.

Syntax

kill [options] pid...

Arguments

• pid: One or more process IDs.

Options Table

Examples

kill -TERM 1234
kill -HUP $(cat /var/run/nginx.pid)

Real-world Usage

Use -TERM before -KILL to allow cleanup and logs to flush.

Common Mistakes

• Using -KILL immediately without trying graceful signals.
• Killing the wrong PID by copying stale output.

Performance Notes

Signals are immediate, but process cleanup may take time.

Security Considerations

Only privileged users should send signals to system processes.

Related Commands

pkill, pgrep, systemctl

Practice Exercises

1. Send HUP to a daemon to reload configuration.
2. Identify a stuck process and terminate it gracefully.