Text and logs · Lesson 23 of 38 · 8 minutes

Logrotate config review

Read log rotation settings as text.

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 rotation config
Run cat /etc/logrotate.d/nginx.
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.
```
cat /etc/logrotate.d/nginx
```
Remember: Reading a source file should precede changing it; avoid printing real secrets.
2
Find retention count
Run grep rotate /etc/logrotate.d/nginx.
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 rotate /etc/logrotate.d/nginx
```
Remember: No matches is exit status 1, which is different from a malformed invocation.
3
Preview config window
Run sed 1,3p /etc/logrotate.d/nginx.
Hint & worked example
Preview a supported substitution or line range without changing the source file.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
sed 1,3p /etc/logrotate.d/nginx
```
Remember: Without a global flag, a substitution normally changes only the first match on each line.

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.
sed: Preview a supported substitution or line range without changing the source file.
Without a global flag, a substitution normally changes only the first match on each line.

Worked example and expected result

$ cat /etc/logrotate.d/nginx

/var/log/nginx-*.log {
  daily
  rotate 7
  compress
  missingok
  notifempty
}

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

$ grep rotate /etc/logrotate.d/nginx

  rotate 7

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

$ sed 1,3p /etc/logrotate.d/nginx

/var/log/nginx-*.log {
  daily
  rotate 7

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

Apply it elsewhere

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

Keep the momentum.

Complete the lab, then explain and apply the pattern.

Next: Logrotate dry run 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