To restart the NTPD (Network Time Protocol daemon) service on a Linux system, you can use the following command:
sudo systemctl restart ntpd
This command will restart the NTPD service and apply any changes that you have made to its configuration. If you are using a different init system (such as System V or Upstart), you may need to use a different command to restart the NTPD service. For example, on a System V-based system, you can use the following command:
sudo service ntpd restart
Remember to use sudo to execute the command with root privileges, as the NTPD service is typically run as the root user.