Cron log monitoring in Linux CLI - Mini Project: Build & Apply

Cron Log Monitoring

📖 Scenario: You are a system administrator who wants to monitor cron job executions on a Linux server. Cron jobs run scheduled tasks, and their logs are stored in a system file. You want to check how many cron jobs ran successfully today.

🎯 Goal: Build a simple script that reads the cron log file, filters entries for today's date, counts how many cron jobs ran successfully, and displays the count.

📋 What You'll Learn

Use the grep command to filter cron logs by today's date

Use the grep command to filter successful cron job entries

Use the wc -l command to count the number of matching lines

Store intermediate results in variables

Print the final count with a descriptive message

💡 Why This Matters

🌍 Real World

System administrators often need to monitor cron jobs to ensure scheduled tasks run correctly and troubleshoot failures.

💼 Career

Knowing how to parse logs and automate monitoring with shell commands is a key skill for DevOps and system administration roles.

1

Set the date variable

Create a variable called today that stores the current date in the format MMM DD (e.g., Jun 15) using the date command.

Linux CLI

# Create a variable called today with the current date in 'MMM DD' format
# Your code here

Need a hint?

Use date '+%b %e' to get the month abbreviation and day with a space for single-digit days.

2

Filter cron log entries for today

Use the grep command to filter lines from /var/log/cron that contain the date stored in the today variable. Store the result in a variable called today_logs.

Linux CLI

today=$(date '+%b %e')
# Filter /var/log/cron for lines containing $today and store in today_logs
# Your code here

Need a hint?

Use double quotes around $today to expand the variable inside grep.

3

Count successful cron job runs

Use grep to filter lines from today_logs that contain the word CMD, which indicates a cron job command ran. Then use wc -l to count these lines. Store the count in a variable called success_count.

Linux CLI

today=$(date '+%b %e')
today_logs=$(grep "$today" /var/log/cron)
# Count lines containing 'CMD' in today_logs and store in success_count
# Your code here

Need a hint?

Use echo "$today_logs" | grep 'CMD' | wc -l to count matching lines.

4

Display the count of successful cron jobs

Print the message "Number of cron jobs run today: X" where X is the value of the success_count variable.

Linux CLI

today=$(date '+%b %e')
today_logs=$(grep "$today" /var/log/cron)
success_count=$(echo "$today_logs" | grep 'CMD' | wc -l)
# Print the number of cron jobs run today
# Your code here

Need a hint?

Use echo with double quotes and variable expansion to print the message.