Server operations · Lesson 15 of 36 · 7 minutes

Scheduled tasks

Inspect simulated cron configuration and related logs.

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Your objectives

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1
Read crontab
Run cat /etc/crontab.
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/crontab
```
Remember: Reading a source file should precede changing it; avoid printing real secrets.
2
Search cron logs
Run grep cron /var/log/syslog.
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 cron /var/log/syslog
```
Remember: No matches is exit status 1, which is different from a malformed invocation.
3
Check cron service
Run systemctl status cron.
Hint & worked example
Inspect or change a simulated systemd service. Status, active state, and unit configuration reveal different evidence.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
systemctl status cron
```
Remember: A service can be active while an application endpoint is unhealthy; verify both layers.

Understand the pattern

Timers and cron jobs are common sources of surprise changes.

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.
systemctl: Inspect or change a simulated systemd service. Status, active state, and unit configuration reveal different evidence.
A service can be active while an application endpoint is unhealthy; verify both layers.

Worked example and expected result

$ cat /etc/crontab

SHELL=/bin/sh
*/15 * * * * root /usr/local/bin/fake-maintenance
# training cron only

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

$ grep cron /var/log/syslog

May 26 08:15:00 clairos-learn cron[126]: ran fake maintenance

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

$ systemctl status cron

cron.service - simulated cron
   Loaded: loaded
   Active: active
   Notes: running scheduled simulated maintenance

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 “Scheduled tasks”, 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 “Scheduled tasks” 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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