Troubleshooting · Lesson 1 of 26 · 8 minutes

Triage baseline

Start troubleshooting with system, service, and capacity facts.

Open the lab Course map

Mastery 0/3Run itExplain itApply it

learner@clairos:~ $

↑ history · Tab complete · Ctrl+C cancel · Esc, Tab to leaveExit 0

Your objectives

Hints are always available. Wrong turns never cost XP.

1
Check load
Run uptime.
Hint & worked example
Read simulated runtime and load information.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
uptime
```
Remember: Load average is not a direct CPU percentage.
2
Check disk
Run df -h.
Hint & worked example
Inspect the virtual filesystem capacity report. Real systems can run out of space or inodes independently.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
df -h
```
Remember: Available space is a snapshot, not a guarantee that a later write will succeed.
3
Check nginx
Run systemctl status nginx.
Hint & worked example
Inspect or change a simulated systemd service. Status, active state, and unit configuration reveal different evidence.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
systemctl status nginx
```
Remember: A service can be active while an application endpoint is unhealthy; verify both layers.

Understand the pattern

Junior operators build confidence by gathering evidence before changing systems.

uptime: Read simulated runtime and load information.
Load average is not a direct CPU percentage.
df: Inspect the virtual filesystem capacity report. Real systems can run out of space or inodes independently.
Available space is a snapshot, not a guarantee that a later write will succeed.
systemctl: Inspect or change a simulated systemd service. Status, active state, and unit configuration reveal different evidence.
A service can be active while an application endpoint is unhealthy; verify both layers.

Worked example and expected result

$ uptime

 10:26:04 up 12 days,  4:18,  1 learner,  load average: 0.04, 0.03, 0.01

Exit status: 0. The command completed successfully in the training fixture.

$ df -h

Filesystem      Size  Used Avail Use% Mounted on
lab-root         20G  6.4G   14G  32% /
lab-logs        2.0G  180M  1.9G   9% /var/log

Exit status: 0. The command completed successfully in the training fixture.

$ systemctl status nginx

nginx.service - simulated nginx
   Loaded: loaded
   Active: active
   Notes: serving the simulated static learn site

Exit status: 0. The command completed successfully in the training fixture.

Try a variation

Repeat this workflow in the sandbox with a different scratch filename. Keep the system fixtures unchanged and compare the observed output with your expectation before moving on.

Explain it

In “Triage baseline”, which interpretation is safe?A command appearing in history proves it completed successfully.A successful first check guarantees that every dependent service is healthy.Available space is a snapshot, not a guarantee that a later write will succeed.

Apply it elsewhere

Before adapting the df workflow from “Triage baseline” to another server, what should you do?Skip output inspection whenever the command is familiar.Confirm the current directory, target identity, permissions, and the installed command behavior first.Paste the training paths unchanged into production.

Keep the momentum.

Complete the lab, then explain and apply the pattern.

Next: Failed service drill Try an incident drill

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