Troubleshooting · Lesson 8 of 26 · 8 minutes

Package change triage

Use package logs to explain recent changes.

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

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1
Find upgrades
Run grep upgrade /var/log/dpkg.log.
Hint & worked example
Select input lines that match a pattern; -i ignores case, -n adds line numbers, and -v inverts selection.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
grep upgrade /var/log/dpkg.log
```
Remember: No matches is exit status 1, which is different from a malformed invocation.
2
Check package policy
Run apt policy fake-openssh.
Hint & worked example
Inspect a fixed training package inventory. The simulator cannot install or upgrade your computer.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
apt policy fake-openssh
```
Remember: Candidate, installed, and repository versions answer different questions.
3
Check status
Run dpkg -s fake-openssh.
Hint & worked example
Inspect installed-package records in the synthetic Debian-style environment.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
dpkg -s fake-openssh
```
Remember: Repository availability and installed package state are separate evidence.

Understand the pattern

Junior operators build confidence by gathering evidence before changing systems.

grep: Select input lines that match a pattern; -i ignores case, -n adds line numbers, and -v inverts selection.
No matches is exit status 1, which is different from a malformed invocation.
apt: Inspect a fixed training package inventory. The simulator cannot install or upgrade your computer.
Candidate, installed, and repository versions answer different questions.
dpkg: Inspect installed-package records in the synthetic Debian-style environment.
Repository availability and installed package state are separate evidence.

Worked example and expected result

$ grep upgrade /var/log/dpkg.log

2026-05-26 08:01:00 upgrade fake-openssh 9.9

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

$ apt policy fake-openssh

fake-openssh:
  Installed: 1.0-training
  Candidate: 1.0-training
  Version table: simulated

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

$ dpkg -s fake-openssh

Package: fake-openssh
Status: install ok installed
Version: 1.0-training

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 “Package change triage”, which interpretation is safe?A command appearing in history proves it completed successfully.A successful first check guarantees that every dependent service is healthy.Candidate, installed, and repository versions answer different questions.

Apply it elsewhere

Before adapting the apt workflow from “Package change triage” 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.

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