September 28, 2025

Quick Guide: Sync the Clock on Any Linux Server

Keep Linux clocks correct in seconds. This quick guide gives copy‑paste one‑liners for chrony, systemd‑timesyncd, and legacy ntpd across RHEL/Alma/Rocky, Amazon Linux, Ubuntu/Debian, and SUSE. Includes verification commands, common gotchas, and how to point at your own NTP servers.

Time drift breaks TLS, logs, Kerberos, cron, and more. Here’s a fast, copy‑pasteable guide to bring the clock into sync on today’s major Linux distributions—without wading through man pages.

TL;DR – One‑liners

chrony (most common on servers):

sudo systemctl enable --now chronyd && sudo chronyc -a makestep && sudo hwclock --systohc

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sudo systemctl enable --now chronyd && sudo chronyc -a makestep && sudo hwclock --systohc

systemd‑timesyncd (minimal hosts/containers):

sudo timedatectl set-ntp true && sudo systemctl restart systemd-timesyncd && sudo hwclock --systohc

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sudo timedatectl set-ntp true && sudo systemctl restart systemd-timesyncd && sudo hwclock --systohc

Legacy ntpd:

sudo systemctl enable --now ntpd && sudo ntpd -gq && sudo hwclock --systohc

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sudo systemctl enable --now ntpd && sudo ntpd -gq && sudo hwclock --systohc

Verify:

timedatectl status

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timedatectl status

What you’re doing (and why)

Enable a time service so the clock keeps syncing (chrony, timesyncd, or ntpd).
Force an immediate step to fix any large drift now.
Write to hardware clock so the setting persists across reboots.

Pick the right command for your distro

RHEL / CentOS / AlmaLinux / Rocky (7–9)

Default is chrony (RHEL 7+). Use:

sudo systemctl enable --now chronyd && sudo chronyc -a makestep && sudo hwclock --systohc

1 2	sudo systemctl enable --now chronyd && sudo chronyc -a makestep && sudo hwclock --systohc

Check:

chronyc tracking && chronyc sources -v

1 2	chronyc tracking && chronyc sources -v

Amazon Linux 2 & 2023

Amazon Linux defaults to chrony. Use the same commands:

sudo systemctl enable --now chronyd && sudo chronyc -a makestep && sudo hwclock --systohc

1 2	sudo systemctl enable --now chronyd && sudo chronyc -a makestep && sudo hwclock --systohc

Ubuntu / Debian

Server installs often ship with systemd-timesyncd by default; many admins prefer chrony for richer controls. Pick one:

timesyncd (simple):

sudo timedatectl set-ntp true && sudo systemctl restart systemd-timesyncd && sudo hwclock --systohc

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sudo timedatectl set-ntp true && sudo systemctl restart systemd-timesyncd && sudo hwclock --systohc
chrony (recommended on servers):

sudo apt-get update && sudo apt-get install -y chrony \ && sudo systemctl enable --now chronyd \ && sudo chronyc -a makestep && sudo hwclock --systohc

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sudo apt-get update && sudo apt-get install -y chrony \
&& sudo systemctl enable --now chronyd \
&& sudo chronyc -a makestep && sudo hwclock --systohc

SUSE / openSUSE

Modern releases use chrony:

sudo systemctl enable --now chronyd && sudo chronyc -a makestep && sudo hwclock --systohc

1 2	sudo systemctl enable --now chronyd && sudo chronyc -a makestep && sudo hwclock --systohc

Older/Legacy hosts using ntpd

If you’re stuck on ntpd:

sudo systemctl enable --now ntpd && sudo ntpd -gq && sudo hwclock --systohc

1 2	sudo systemctl enable --now ntpd && sudo ntpd -gq && sudo hwclock --systohc

Tip: ntpd -gq corrects large offsets once and exits; the service keeps it in sync afterward.

How to tell what you’re running

# Is chrony active?
systemctl is-active --quiet chronyd && echo "chrony"
# Is systemd-timesyncd present?
systemctl list-unit-files | grep -q systemd-timesyncd && echo "timesyncd"
# Is ntpd installed?
command -v ntpd >/dev/null && echo "ntpd"
# Quick status view
sudo timedatectl status

# Is chrony active?

systemctl is-active --quiet chronyd && echo "chrony"

# Is systemd-timesyncd present?

systemctl list-unit-files | grep -q systemd-timesyncd && echo "timesyncd"

# Is ntpd installed?

command -v ntpd >/dev/null && echo "ntpd"

# Quick status view

sudo timedatectl status

Verify it worked

Universal: timedatectl status (look for System clock synchronized: yes).
chrony: chronyc tracking (check Reference ID, Root delay, Offset).
ntpd: ntpq -p (see peers and reachability).

You should also see your timezone and NTP service enabled:

timedatectl | sed -n '1,6p'

1 2	timedatectl \| sed -n '1,6p'

Common gotchas (quick fixes)

No network egress to NTP: allow UDP/123 to the internet or your internal NTP servers.
Virtual machines drifting: ensure the hypervisor provides stable time; still keep NTP in the guest.
Containers: prefer the host to handle time; in a container use timedatectl/timesyncd only if it’s a full systemd container. For app containers, avoid bundling NTP.
Large jumps fail to smooth: chronyc -a makestep (chrony) or ntpd -gq (ntpd) permits big corrections.
Hardware clock errors: some cloud VMs don’t expose a hardware clock—omit hwclock --systohc if it errors.

One command to “just fix it” (best‑effort)

If you’re not sure which client you have, this tries chrony → timesyncd → ntpd, then writes the hardware clock:

( command -v chronyc >/dev/null && sudo systemctl enable --now chronyd && sudo chronyc -a makestep ) \
|| ( systemctl list-unit-files | grep -q systemd-timesyncd && sudo timedatectl set-ntp true && sudo systemctl restart systemd-timesyncd ) \
|| ( command -v ntpd >/dev/null && sudo systemctl enable --now ntpd && sudo ntpd -gq ); \
sudo hwclock --systohc || true

( command -v chronyc >/dev/null && sudo systemctl enable --now chronyd && sudo chronyc -a makestep ) \

|| ( systemctl list-unit-files | grep -q systemd-timesyncd && sudo timedatectl set-ntp true && sudo systemctl restart systemd-timesyncd ) \

|| ( command -v ntpd >/dev/null && sudo systemctl enable --now ntpd && sudo ntpd -gq ); \

sudo hwclock --systohc || true

Appendix: Point to your own NTP servers

chrony: edit /etc/chrony.conf (or /etc/chrony/chrony.conf on Debian/Ubuntu) and replace pool … lines with server ntp1.example.com iburst entries. Then sudo systemctl restart chronyd.
timesyncd: set NTP=ntp1.example.com ntp2.example.com in /etc/systemd/timesyncd.conf, then sudo systemctl restart systemd-timesyncd.
ntpd: set server ntp1.example.com iburst in /etc/ntp.conf, then sudo systemctl restart ntpd.