Monday Mission: How to Look Up Cron Syntax Fast

[TudorRaduta]

Happy Monday, everyone!

Let’s kick off the week with a better study habit. For a long time, I tried to memorize the exact order of the crontab fields. It turns out that’s not the best approach.

The Mission

The real RHCSA skill isn’t memorizing every detail. It’s knowing how to find information quickly with the tools built into the system. For cron, that means using the man pages.

Here’s the built-in map you can rely on during the exam. It shows the exact syntax and options you need.

The Real Map: man 5 crontab

Tip: Section 5 covers file formats, which is exactly what crontab is.

Your Turn

1. What is one thing you stopped memorizing and now look up quickly with man or info?
2. Quick challenge: Using man 5 crontab, write the cron line to run /usr/local/bin/backup.sh at 02:30 every Sunday.

Drop your answers in the comments. Let’s work smarter, not harder.

[Priyanshu20041]

Step 1: Open the correct manual page

Cron syntax is a file format, so we check section 5

# man 5 crontab

Step 2: Understand the field order

From the man page, the format is:

# minute hour day-of-month month day-of-week command

Step 3: Translate the requirement

• 02:30 AM → minute 30 , hour 2

• Every day of the month → *

• Every month →*

• Every Sunday → 0 (or 7on some systems)

• Command → /usr/local/bin/backup.sh 

Step 4: Write the cron entry

# 30 2 * * 0 /usr/local/bin/backup.sh

Step 5: Validate the approach

This matches exactly what man 5 crontab  documents and works reliably across RHEL-based systems.

Instead of memorizing, I now routinely check man pages like:

• man 5 crontab

•  man systemd.service

• man firewalld.zone

It’s faster, safer, and more accurate — especially in exams and production.