Processes, ps, pstree, top, kill, nice, jobs, at and cron. You only read what is right for you: pick a path, and every topic shows just that level. Switch level on any topic whenever you want to go simpler or deeper.
👆 Pick a path to begin. You can change it any time.
💻 The Process Lab terminal
A safe simulated server with real-looking processes. You are user student. Missions are grouped by level (B / I / E) and follow your chosen path. Type help to see supported commands.
Try: ps -ef | grep sshd · pstree -p · top · kill 3150 · renice -n 10 -p 2890 · sleep 300 & · jobs · kill -9 3777 · echo "0 2 * * * /home/student/backup.sh" | crontab -. ↑ recalls history.
🎯 MCQ Challenge
10 questions per level (30 in total). +10 XP for each question answered correctly for the first time, +5 bonus for every 3rd correct in a row. Score 90%+ in a set for the Quiz Master badge.
❓ FAQ: questions learners really ask
🗣️ Practice questions with model answers
Answer in your own words first, then reveal. These are typical exam and interview questions.
🏆 Cheat sheet and key takeaways
| I want to… | Command |
|---|---|
| List all processes | ps -ef · ps aux |
| Find one service | ps -ef | grep sshd · pgrep -a sshd · pidof sshd |
| See the family tree | pstree -p · pstree -a |
| Watch live usage | top (q quit, M mem, P CPU) · top -b -n 1 |
| Stop a process | kill PID then kill -9 PID if needed |
| Pause / resume | kill -19 PID / kill -18 PID |
| Change priority | nice -n 10 cmd · renice -n 10 -p PID |
| Background / foreground | cmd & · Ctrl+Z · bg %1 · fg %1 · jobs |
| Survive logout | nohup cmd & · tmux · systemd unit |
| Run once later | at 17:30 · atq · atrm N |
| Run repeatedly | crontab -e · crontab -l · 0 2 * * * /path/cmd |
Linux runs daemons, services and programs as processes with a PID · ps and pstree display them · top shows them live with resource use · kill, nice and renice control them · at and cron schedule when commands run.
🎓 Your progress
Earn 180 XP to unlock your summary.