Linux systemd Timers Guide

⏰ Linux systemd Timers Guide

Complete beginner-friendly guide to systemd timers on Linux, covering Arch Linux, CachyOS, and other distributions including creating timers, scheduling tasks, and replacing cron.

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Table of Contents

1. Understanding systemd Timers
2. Creating Timers
3. Timer Configuration
4. Timer Management
5. Troubleshooting

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Understanding systemd Timers

What are systemd Timers?

systemd timers are systemd's replacement for cron.

Advantages:

• Logging: Integrated with journald
• Dependencies: Can depend on other units
• Calendar: Flexible scheduling
• OnBoot/OnCalendar: Multiple trigger types

Components:

• Timer unit: .timer file
• Service unit: .service file (what to run)

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Creating Timers

Create Service

Create service file:

# Create service
sudo vim /etc/systemd/system/my-task.service

Add:

[Unit]
Description=My Task

[Service]
Type=oneshot
ExecStart=/usr/bin/my-script.sh

Create Timer

Create timer file:

# Create timer
sudo vim /etc/systemd/system/my-task.timer

Add:

[Unit]
Description=Run My Task

[Timer]
OnCalendar=daily
OnBootSec=15min

[Install]
WantedBy=timers.target

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Timer Configuration

Calendar Format

OnCalendar syntax:

OnCalendar=Mon *-*-* 00:00:00  # Every Monday
OnCalendar=*-*-* 02:00:00       # Daily at 2 AM
OnCalendar=*-*-01 00:00:00      # Monthly on 1st
OnCalendar=hourly               # Every hour

Relative Time

Relative timers:

OnBootSec=15min
OnUnitActiveSec=1h
OnStartupSec=10min

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Timer Management

Enable Timer

Enable and start:

# Enable timer
sudo systemctl enable my-task.timer

# Start timer
sudo systemctl start my-task.timer

# Check status
systemctl status my-task.timer

List Timers

View timers:

# List all timers
systemctl list-timers

# List active timers
systemctl list-timers --active

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Troubleshooting

Timer Not Running

Check status:

# Check timer
systemctl status my-task.timer

# Check service
systemctl status my-task.service

# Check logs
journalctl -u my-task.service

Timer Errors

Check configuration:

# Test timer
systemctl list-timers my-task.timer

# Check service
systemctl cat my-task.service

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Summary

This guide covered systemd timers, creating scheduled tasks, and timer management for Arch Linux, CachyOS, and other distributions.

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Next Steps

• systemd Advanced - Advanced systemd
• System Configuration - System setup
• systemd Timers: https://wiki.archlinux.org/title/Systemd/Timers

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