Security administration · Lesson 25 of 35 · 8 minutes

Account inventory review

Inventory users, groups, and service accounts.

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
List users
Run cut -d : -f 1 /etc/passwd.
Hint & worked example
Extract delimiter-separated fields or character ranges from text.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
cut -d : -f 1 /etc/passwd
```
Remember: A delimiter parser is not a general CSV parser with quoted fields.
2
Find web user
Run grep www-data /etc/passwd.
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 www-data /etc/passwd
```
Remember: No matches is exit status 1, which is different from a malformed invocation.
3
Show learner identity
Run id.
Hint & worked example
Inspect user identity and group membership.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
id
```
Remember: A file group is useful only when the acting user belongs to it or has an applicable override.

Understand the pattern

Junior operators build confidence by gathering evidence before changing systems.

cut: Extract delimiter-separated fields or character ranges from text.
A delimiter parser is not a general CSV parser with quoted fields.
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.
id: Inspect user identity and group membership.
A file group is useful only when the acting user belongs to it or has an applicable override.

Worked example and expected result

$ cut -d : -f 1 /etc/passwd

root
learner
www-data

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

$ grep www-data /etc/passwd

www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin

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

$ id

uid=1000(learner) gid=1000(learners) groups=1000(learners),27(sudo-readonly)

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 “Account inventory review”, which interpretation is safe?A command appearing in history proves it completed successfully.A successful first check guarantees that every dependent service is healthy.No matches is exit status 1, which is different from a malformed invocation.

Apply it elsewhere

Before adapting the grep workflow from “Account inventory review” 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: Package security deep review Try an incident drill

Anonymous lesson and mastery progress lasts for this session. Sign in to keep synced lesson XP between sessions; mastery stays device-local. No speed bonus, lost lives, or hint penalties.

Keep learning

GNU Coreutils manual · GNU Bash manual