Crontab Real-World Scenario Quiz

Scenario 1 Not answered

Scenario: A Linux server needs to run a backup script every night at 2:00 AM. The script is located at `/opt/scripts/backup.sh`.

Which cron entry is correct?

* 2 * * * /opt/scripts/backup.sh 0 2 * * * /opt/scripts/backup.sh 2 0 * * * /opt/scripts/backup.sh 0 * 2 * * /opt/scripts/backup.sh

Explanation: `0 2 * * *` means minute 0, hour 2, every day. So it runs daily at 2:00 AM.

Scenario 2 Not answered

Scenario: Your DevOps team wants to run a health check script every 5 minutes. The script is `/opt/scripts/health-check.sh`.

Which cron expression should you use?

5 * * * * /opt/scripts/health-check.sh */5 * * * * /opt/scripts/health-check.sh * */5 * * * /opt/scripts/health-check.sh 0 5 * * * /opt/scripts/health-check.sh

Explanation: `*/5` in the minute field means every 5 minutes.

Scenario 3 Not answered

Scenario: A script works manually, but it does not run from cron. The crontab entry is `* * * * * backup.sh`.

What is the most likely issue?

Cron cannot run every minute The script name is too short Full path is missing Cron only runs Python scripts

Explanation: Cron has a limited environment. Use the full path, such as `/home/khalid/scripts/backup.sh`.

Scenario 4 Not answered

Scenario: A backup cron job runs, but you cannot see any output or errors.

What should you add to the cron entry?

Redirect output and errors to a log file Remove the script Disable cron service Move the script to `/tmp` only

Explanation: Use `>> /var/log/backup.log 2>&1` to append output and errors to a log file.

Scenario 5 Not answered

Scenario: Your manager wants a report generated every Monday to Friday at 9:00 AM.

Which cron entry is correct?

9 0 * * 1-5 /opt/scripts/report.sh 0 9 * * 1-5 /opt/scripts/report.sh 0 9 1-5 * * /opt/scripts/report.sh */9 * * * 1-5 /opt/scripts/report.sh

Explanation: `0 9 * * 1-5` means 9:00 AM, Monday through Friday.

Scenario 6 Not answered

Scenario: A cron job is scheduled correctly, but the script does not execute. You check the file and see `-rw-r--r--` permissions.

What should you do?

Delete the script Make the script executable with `chmod +x` Restart the server only Change only the cron time

Explanation: The script needs execute permission. Use `chmod +x /opt/scripts/cleanup.sh`.

Scenario 7 Not answered

Scenario: A job needs to clean system cache and requires root permission.

Where should you place the cron job?

Normal user crontab only Root crontab using `sudo crontab -e` Inside `/home/user/Documents` In browser settings

Explanation: If a job requires root permissions, schedule it in root's crontab with `sudo crontab -e`.

Scenario 8 Not answered

Scenario: A cron job runs every 5 minutes, but sometimes the previous run is still running when the next one starts.

What should you use to prevent overlapping runs?

grep chmod flock pwd

Explanation: `flock` uses a lock file so a new run does not start if the previous run is still active.

Scenario 9 Not answered

Scenario: A cron job did not run on an Ubuntu server.

Which command can help check cron logs?

grep CRON /var/log/syslog cat /etc/passwd df -h lsblk

Explanation: On Ubuntu/Debian, cron logs are commonly found in `/var/log/syslog`.

Scenario 10 Not answered

Scenario: Your SRE team wants to run a maintenance script on the first day of every month at midnight.

Which cron expression is correct?

1 0 * * * /opt/scripts/maintenance.sh 0 1 0 * * /opt/scripts/maintenance.sh 0 0 1 * * /opt/scripts/maintenance.sh * * 1 0 0 /opt/scripts/maintenance.sh

Explanation: `0 0 1 * *` means midnight on the first day of every month.

Result

Which cron entry is correct?

Which cron expression should you use?

What is the most likely issue?

What should you add to the cron entry?

Which cron entry is correct?

What should you do?

Where should you place the cron job?

What should you use to prevent overlapping runs?

Which command can help check cron logs?

Which cron expression is correct?