Stage 4 · Lesson 4 of 8

Stopping processes: signals and kill

You stop a by sending it a , a small message from the system. Pressing sends SIGINT to the program in front of you. kill PID sends SIGTERM, a polite request to finish up and exit.

kill -9 PID sends SIGKILL, which the program cannot catch or ignore. It stops at once, with no chance to save data or tidy up its . pkill -f name sends a signal to processes by name.

Well-written programs handle SIGTERM so they can finish their work cleanly, which matters later for servers and .

Common trapreaching for kill -9 first, which can leave half-written files and stale lock files behind.

A question to check yourself, an AI practice session and 1 cheat sheet entry come when you add the roadmap to your account. Add it

Resources for this stage

Start with· follow one of these

BookFree
The Linux Command Line
William Shotts · Beginner
Its chapters on permissions and processes are the clearest free explanation of this stage
GuideFree
The Linux Command Line for Beginners (Ubuntu)
Canonical · Beginner
Includes a short, careful section on the superuser and when to use sudo

Practise

OverTheWire: Bandit
Later levels need permissions, setuid binaries and processes to progress

Keep handy

nvm (Node Version Manager)
The official README for installing nvm and switching Node versions per project
Windows Subsystem for Linux Documentation
How WSL handles Linux permissions and Windows files, and its troubleshooting guide

Also worth your time

roadmap.sh: LinuxGo deeper
See the users, permissions and process management branches of the Linux map