Permissions and users · Lesson 25 of 33 · 8 minutes

Sudoers readonly review

Read a limited sudo rule without changing privileges.

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
Read sudo rule
Run sudo cat /etc/sudoers.d/learners.
Hint & worked example
Read one or more files to standard output without editing their contents.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
sudo cat /etc/sudoers.d/learners
```
Remember: Reading a source file should precede changing it; avoid printing real secrets.
2
Find sudo marker
Run sudo grep NOPASSWD /etc/sudoers.d/learners.
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.
```
sudo grep NOPASSWD /etc/sudoers.d/learners
```
Remember: No matches is exit status 1, which is different from a malformed invocation.
3
Inspect sudo rule file
Run stat /etc/sudoers.d/learners.
Hint & worked example
Inspect a file or directory metadata record, including ownership, permissions, and size.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
stat /etc/sudoers.d/learners
```
Remember: Metadata and file contents answer different questions.

Understand the pattern

Junior operators build confidence by gathering evidence before changing systems.

cat: Read one or more files to standard output without editing their contents.
Reading a source file should precede changing it; avoid printing real secrets.
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.
stat: Inspect a file or directory metadata record, including ownership, permissions, and size.
Metadata and file contents answer different questions.

Worked example and expected result

$ sudo cat /etc/sudoers.d/learners

learner ALL=(root) NOPASSWD: /usr/bin/systemctl status *
# fake readonly training rule

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

$ sudo grep NOPASSWD /etc/sudoers.d/learners

learner ALL=(root) NOPASSWD: /usr/bin/systemctl status *

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

$ stat /etc/sudoers.d/learners

Path: /etc/sudoers.d/learners
Type: file
Mode: -r--r-----
Owner: root
Group: root
Size: 86 bytes

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 “Sudoers readonly 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 “Sudoers readonly 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: Web root mode 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