How to Sync Linux Server Time with NTP, ntpdate, and Chrony

1. Sync Time Using the NTP Service

Install the ntp package and start the service:

# yum -y install ntp
# systemctl start ntpd
# systemctl enable ntpd

Verify the service status: # systemctl status ntpd Edit /etc/ntp.conf to use a public server (e.g., server ntp.aliyun.com iburst) and restart the service:

# vim /etc/ntp.conf
# systemctl restart ntpd

Check synchronization with:

# ntpq -p

2. One‑off Sync with ntpdate

Run the command to adjust the clock immediately: # ntpdate ntp.aliyun.com Confirm the current time:

# date

3. Fixing ntpdate Sync Failures

If you encounter the error "the NTP socket is in use", stop the running NTP daemon first: # service ntpd stop # or: systemctl stop ntpd Then retry the synchronization:

# ntpdate ntp1.aliyun.com

4. Using Chrony for Time Synchronization

Install Chrony and enable it:

# yum -y install chrony
# systemctl enable --now chronyd

Check its status: # systemctl status chronyd Modify /etc/chrony.conf to point to a preferred server (e.g., server ntp1.aliyun.com iburst) and restart:

# vim /etc/chrony.conf
# systemctl restart chronyd

Verify the source list:

# chronyc sources

5. Manual Time Adjustments

Set the system clock directly:

# date -s "2012-05-23 01:01:01"
# date

Alternative date format (MMDDhhmmYYYY.ss): # date 090621282021.28 Synchronize hardware clock to system clock: # hwclock -w Display the date in a custom format: # date "+%Y-%m-%d %H:%M:%S" Set the timezone to Shanghai:

# timedatectl list-timezones | grep Shanghai
# timedatectl set-timezone Asia/Shanghai