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rootnode-academy/content/root/root-01-computing-linux-foundations/m05-processes/02-demonstration-watching-a-process-die.md
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ced4568andClaude Sonnet 5 15b616274b feat(root01): author Computing & Linux Foundations, and the real 01->05 prerequisite chain
Adds all 6 ROOT 01 modules (how computers run software, the shell, filesystem navigation,
files & text, processes, users & permissions foundations), each with a real lesson,
demonstration/guided exercise, knowledge check where warranted, a hands-on Lab, and a
reflection — 35 activities, 29 new content files.

Adds 6 new hands-on Linux scenarios (linux-inspect-hardware, linux-shell-basics,
linux-filesystem-navigation, linux-files-and-text, linux-process-management,
linux-permissions-foundations) plus 2 MCQ scenarios, using the existing generic scenario/
validation engine (docs/ROOT_FOUNDATIONS_LAB_STRATEGY.md §1) — every one tested end-to-end via
the real scenario setup/validate API, including negative tests confirming they correctly FAIL
when not actually solved (e.g. the process-management scenario fails while the target process
is still running; the permissions scenario is tested against a real `su - labuser` denial).

Wires rootnode-linux-foundations-assessment (2 required + 4 random-draw scenarios) using the
existing Phase 3B assessment engine.

Adds a real, server-side ROOT 01->02->03->04->05 course prerequisite chain
(courses.prerequisites) — verified live on two students: one who completed ROOT 01 sees ROOT 02
unlock; a fresh student sees ROOT 02 correctly locked while 03/04/05 stay vacuously satisfied
(their own prerequisite courses are still empty). ROOT 06+ and the Capstone are unaffected.

Co-Authored-By: Claude Sonnet 5 <[email protected]>
2026-08-26 12:59:52 -05:00

54 lines
1.1 KiB
Markdown

# Demonstration: Watching a Process Actually Terminate
## OBSERVE
Start a long-running background process and note its PID:
```
$ sleep 300 &
[1] 1421
```
`1421` is the PID (yours will differ every time).
## HYPOTHESIS
Predict: will `kill -0 1421` print anything if the process is still running?
## INSPECT
```
$ kill -0 1421 && echo "still running"
still running
```
`kill -0` sends no real signal — silence (or, here, our own `echo`) means the process exists.
## CHANGE
Now actually terminate it:
```
$ kill 1421
```
## VERIFY
```
$ kill -0 1421 2>/dev/null && echo "still running" || echo "gone"
gone
```
The exact same check now reports the opposite result — real, observable proof the process is
gone, not an assumption.
## Instructor Notes
**Demo goal:** Make "checking before and after" a visible habit, not just narrated — students
should see the SAME command return a different real answer once state actually changed.
**Approximate timing:** 8 minutes live.
**Common mistake to watch for:** reaching for `kill -9` by default "to be safe" — reinforce that
plain `kill` (SIGTERM) is the correct first attempt almost always.