To sync your linux server’s time with the NTP Pool Time Servers, use the following command.
ntpdate pool.ntp.org
If you’d like to sync with a time server weekly, add a new file named ntpdate-sync to /etc/cron.weekly. Then set the file permissions to 755 and set owner:group to root:root. Finally, exit set the file contents to the following.
#! /bin/sh
/usr/sbin/ntpdate pool.ntp.org
To sync on a custom schedule, add a new file named ntpdate-sync to /etc/cron.d. Then set the file permissions to 644 and set owner:group to root:root. Finally set the file contents as follows.
# /etc/cron.d/ntpdate-sync: crontab fragment for ntpdate
# Run ntpdate every 15 minutes
0,15,30,45 * * * * root /usr/sbin/ntpdate 2>&1 | /usr/bin/tee -a /var/log/cron/ntpdate-sync.log



