Synchronize date and time

Source:

• https://askubuntu.com/questions/228/how-to-set-ubuntu-to-synchronize-my-clock-with-a-time-server

sudo ntpdate pool.ntp.org

See also

• https://www.digitalocean.com/community/tutorials/how-to-set-up-time-synchronization-on-ubuntu-16-04

sudo timedatectl set-ntp on