NTP
NTP 是一种 TCP/IP 协议，用于通过网络同步时间
ubuntu 时间同步
相关服务和工具
由于 Ubuntu 16.04 timedatectl / timesyncd（它们是 systemd 的一部分）替换了大部分ntpdate / ntp。
timedatectl -h #查看帮助
systemctl status systemd-timesyncd # 查看时间同步服务状态
同步服务配置文件
NAME
timesyncd.conf, timesyncd.conf.d - Network Time Synchronization configuration files
SYNOPSIS
/etc/systemd/timesyncd.conf
/etc/systemd/timesyncd.conf.d/*.conf
/run/systemd/timesyncd.conf.d/*.conf
/usr/lib/systemd/timesyncd.conf.d/*.conf
修改NTP= FallbackNTP= 可以修改同步时间服务器(NTP)
timesyncd.conf默认配置
# This file is part of systemd.
#
# systemd is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2.1 of the License, or
# (at your option) any later version.
#
# Entries in this file show the compile time defaults.
# You can change settings by editing this file.
# Defaults can be restored by simply deleting this file.
#
# See timesyncd.conf(5) for details.
[Time]
#NTP=ntp.ubuntu.com
#FallbackNTP=ntp.ubuntu.com
#RootDistanceMaxSec=5
#PollIntervalMinSec=32
#PollIntervalMaxSec=2048