ced4568andClaude Sonnet 5
15b616274b
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]>
50 lines
1.4 KiB
Markdown
50 lines
1.4 KiB
Markdown
# Demonstration: Watching Exit Codes in Real Time
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## OBSERVE
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Run a command you know will succeed, then immediately check its exit code:
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```
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$ true
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$ echo $?
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0
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```
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## HYPOTHESIS
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Now predict: what will the exit code be if the command fails instead?
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## INSPECT
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Run a command that fails, and check immediately:
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```
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$ ls /this-does-not-exist
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ls: cannot access '/this-does-not-exist': No such file or directory
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$ echo $?
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2
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```
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## CHANGE
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Try a few other failing commands and note their codes: `grep nomatch /etc/hostname` (exit 1 —
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"no matches found," a different kind of failure than "file not found").
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## VERIFY
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Notice: exit codes aren't just "0 or 1" — different failures often get different non-zero
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codes. `0` always means success; the exact non-zero value's MEANING varies by command, but ANY
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non-zero value reliably means "something went wrong," which is the part every script actually
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relies on (`if command; then ... else ...`).
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## Instructor Notes
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**Demo goal:** Make the abstract "exit code" concept concrete by actually watching `$?` change
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in real time, immediately after each command — this is far more convincing live than described
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in prose.
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**Approximate timing:** 8 minutes live.
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**Common mistake to watch for:** running `echo $?` after ANY other command in between (even
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`ls`) silently checks the WRONG command's exit code — emphasize "check it immediately."
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