Linux cron Guide

⏰ Linux cron Guide

Complete beginner-friendly guide to cron on Linux, covering Arch Linux, CachyOS, and other distributions including installation, crontab configuration, and scheduled tasks.

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Table of Contents

1. Understanding cron
2. cron Installation
3. Crontab Configuration
4. Cron Syntax
5. Troubleshooting

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Understanding cron

What is cron?

cron schedules tasks to run automatically.

Components:

• cron daemon: Runs scheduled tasks
• crontab: User's cron configuration
• cron jobs: Scheduled commands

Common uses:

• Backups: Automated backups
• Updates: System updates
• Maintenance: Regular maintenance

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cron Installation

Install cron

Arch/CachyOS:

# Install cronie
sudo pacman -S cronie

# Enable service
sudo systemctl enable --now cronie

Debian/Ubuntu:

sudo apt install cron

Fedora:

sudo dnf install cronie

Verify Installation

Check cron:

# Check service
systemctl status cronie

# Check crontab
crontab -l

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Crontab Configuration

Edit Crontab

Edit user crontab:

# Edit crontab
crontab -e

# List crontab
crontab -l

# Remove crontab
crontab -r

System Crontab

System-wide:

# Edit system crontab
sudo vim /etc/crontab

# Or add to /etc/cron.d/

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⏰ Cron Syntax

Cron Format

Cron syntax:

* * * * * command
│ │ │ │ │
│ │ │ │ └── Day of week (0-7, 0 or 7 = Sunday)
│ │ │ └──── Month (1-12)
│ │ └────── Day of month (1-31)
│ └──────── Hour (0-23)
└────────── Minute (0-59)

Examples

Common examples:

# Every minute
* * * * * command

# Every hour
0 * * * * command

# Daily at midnight
0 0 * * * command

# Weekly on Sunday
0 0 * * 0 command

# Monthly on 1st
0 0 1 * * command

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Troubleshooting

Cron Not Running

Check service:

# Check cron service
systemctl status cronie

# Check logs
journalctl -u cronie

# Or cron log
grep CRON /var/log/syslog

Job Not Executing

Check crontab:

# List crontab
crontab -l

# Check syntax
# Use absolute paths
# Set environment variables

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Summary

This guide covered cron installation, crontab configuration, and scheduled tasks for Arch Linux, CachyOS, and other distributions.

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Next Steps

• System Configuration - System setup
• Backup and Restore - Automated backups
• cron Documentation: man crontab

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This guide covers Arch Linux, CachyOS, and other Linux distributions. For distribution-specific details, refer to your distribution's documentation.