How to synchronize time on systemd system (Ubuntu 15.04) using command line?(Note: simply running timedatectl set_ntp true is not updating the time)
synchronize time by remote server
systemd
To keep your system time synchcronised with a remote server, under systemd  as of version 213 (note: you must be using systemd-networkd to manage your network connectivity) you would use systemd-timesyncd. To start and enable this service, run:timedatectl set-ntp true You can set the time with:timedatectl set-time $current_timeSee man timedatectl for the details.To configure NTP pool servers to synchromise with, add them in /etc/systemd/timesyncd.conf, like so:[Time]NTP=0.arch.pool.ntp.org 1.arch.pool.ntp.org 2.arch.pool.ntp.org 3.arch.pool.ntp.orgFallbackNTP=0.pool.ntp.org 1.pool.ntp.org 0.fr.pool.ntp.orgAs Lennart Poettering notes in the announcement:In contrast to NTP          implementations such as chrony or the NTP reference server          this only implements a client side, and does not bother with          the full NTP complexity, focusing only on querying time from          one remote server and synchronizing the local clock to          it. Unless you intend to serve NTP to networked clients or          want to connect to local hardware clocks this simple NTP          client should be more than appropriate for most          installations.See the man page for the service for details.