Package/process ops · Lesson 3 of 20 · 8 minutes

DPKG package list

Use dpkg to review installed package records.

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Your objectives

Hints are always available. Wrong turns never cost XP.

1
List dpkg packages
Run dpkg -l.
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 -l
```
Remember: Repository availability and installed package state are separate evidence.
2
Show package status
Run dpkg -s fake-nginx.
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-nginx
```
Remember: Repository availability and installed package state are separate evidence.
3
Count package log
Run wc -l /var/log/dpkg.log.
Hint & worked example
Count input. -l counts newline characters, -w counts whitespace-delimited words, and -c counts bytes.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
wc -l /var/log/dpkg.log
```
Remember: Text without a final newline may have fewer counted lines than visible rows.

Understand the pattern

Junior operators build confidence by gathering evidence before changing systems.

dpkg: Inspect installed-package records in the synthetic Debian-style environment.
Repository availability and installed package state are separate evidence.
wc: Count input. -l counts newline characters, -w counts whitespace-delimited words, and -c counts bytes.
Text without a final newline may have fewer counted lines than visible rows.

Worked example and expected result

$ dpkg -l

ii  fake-nginx     1.0  training web server
ii  fake-openssh   9.9  training ssh server
ii  coreutils      9.5  training utilities

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

$ dpkg -s fake-nginx

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

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

$ wc -l /var/log/dpkg.log

2 /var/log/dpkg.log

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 “DPKG package list”, which interpretation is safe?A successful first check guarantees that every dependent service is healthy.Repository availability and installed package state are separate evidence.A command appearing in history proves it completed successfully.

Apply it elsewhere

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

Keep the momentum.

Complete the lab, then explain and apply the pattern.

Next: DPKG files Try an incident drill

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