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Linux Time Synchronization

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Mattscreative edited this page Dec 5, 2025 · 2 revisions

⏰ Linux Time Synchronization Guide

Complete beginner-friendly guide to time synchronization on Linux, covering Arch Linux, CachyOS, and other distributions including NTP, systemd-timesyncd, and timezone configuration.

Table of Contents

  1. Understanding Time Synchronization
  2. Timezone Configuration
  3. systemd-timesyncd
  4. NTP Configuration
  5. Hardware Clock
  6. Troubleshooting

Understanding Time Synchronization

What is Time Synchronization?

Time synchronization keeps system time accurate.

What it does:

  • Accurate time: Keeps time correct
  • Network sync: Syncs with time servers
  • Timezone: Handles timezones
  • Consistency: Consistent time across network

Why it matters:

  • Security: Certificates require accurate time
  • Logs: Accurate timestamps
  • Scheduling: Cron jobs, etc.
  • Network: Network protocols need accurate time

Timezone Configuration

Set Timezone

List timezones:

# List available timezones
timedatectl list-timezones

Set timezone:

# Set timezone
sudo timedatectl set-timezone America/New_York

# Or
sudo timedatectl set-timezone Europe/London

Check timezone:

# Check time and timezone
timedatectl

⏱ systemd-timesyncd

Enable timesyncd

Enable service:

# Enable timesyncd
sudo systemctl enable systemd-timesyncd
sudo systemctl start systemd-timesyncd

# Check status
timedatectl status

Configure timesyncd

Edit config:

# Edit config
sudo vim /etc/systemd/timesyncd.conf

Example:

[Time]
NTP=0.arch.pool.ntp.org 1.arch.pool.ntp.org
FallbackNTP=0.pool.ntp.org 1.pool.ntp.org

Restart service:

sudo systemctl restart systemd-timesyncd

NTP Configuration

Install NTP

Install NTP:

# Arch/CachyOS
sudo pacman -S ntp

# Debian/Ubuntu
sudo apt install ntp

# Fedora
sudo dnf install ntp

Enable NTP

Enable service:

# Enable service
sudo systemctl enable ntpd
sudo systemctl start ntpd

# Check status
systemctl status ntpd

Configure NTP

Edit config:

# Edit config
sudo vim /etc/ntp.conf

Add servers:

server 0.arch.pool.ntp.org
server 1.arch.pool.ntp.org
server 2.arch.pool.ntp.org
server 3.arch.pool.ntp.org

Restart:

sudo systemctl restart ntpd

Hardware Clock

Check Hardware Clock

Check clock:

# Check hardware clock
sudo hwclock --show

# Check system clock
date

Sync Hardware Clock

Sync to system:

# Sync hardware clock to system
sudo hwclock --systohc

# Sync system to hardware clock
sudo hwclock --hctosys

Set Hardware Clock

Set clock:

# Set hardware clock
sudo hwclock --set --date "2024-01-15 10:00:00"

Troubleshooting

Time Not Syncing

Check sync status:

# Check timesyncd
timedatectl status

# Check NTP
ntpq -p

Wrong Timezone

Set timezone:

# List timezones
timedatectl list-timezones

# Set timezone
sudo timedatectl set-timezone Your/Timezone

Summary

This guide covered time synchronization for Arch Linux, CachyOS, and other distributions, including timezone configuration, systemd-timesyncd, NTP, and hardware clock.

Next Steps

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

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