RHEL 7 timedatectl and NTP

查看当前系统时间和NTP是否启用：

[root@localhost ~]# timedatectl
      Local time: Tue 2019-05-28 19:59:48 PDT
  Universal time: Wed 2019-05-29 02:59:48 UTC
        RTC time: Wed 2019-05-29 02:59:48
       Time zone: America/Los_Angeles (PDT, -0700)
     NTP enabled: yes
NTP synchronized: yes
 RTC in local TZ: no
      DST active: yes
 Last DST change: DST began at
                  Sun 2019-03-10 01:59:59 PST
                  Sun 2019-03-10 03:00:00 PDT
 Next DST change: DST ends (the clock jumps one hour backwards) at
                  Sun 2019-11-03 01:59:59 PDT
                  Sun 2019-11-03 01:00:00 PST

查看时区列表：

[root@localhost ~]# timedatectl list-timezones 
Africa/Abidjan
Africa/Accra
Africa/Addis_Ababa
......

设置时区：

[root@localhost ~]# timedatectl set-timezone Asia/Hong_Kong
 

取消NTP：

[root@localhost ~]# timedatectl set-ntp no
[root@localhost ~]# timedatectl status
      Local time: Wed 2019-05-29 11:10:14 HKT
  Universal time: Wed 2019-05-29 03:10:14 UTC
        RTC time: Wed 2019-05-29 03:10:14
       Time zone: Asia/Hong_Kong (HKT, +0800)
     NTP enabled: no
NTP synchronized: yes
 RTC in local TZ: no
      DST active: n/a

启用NTP：

[root@localhost ~]# timedatectl set -ntp yes

NTP服务：

[root@localhost /]# systemctl status chronyd
 

NTP配置文件：

[root@localhost /]# less /etc/chrony.conf 
 

NTP启用状态下无法设置系统时间：

[root@localhost /]# timedatectl set-time "2019-05-29 11:40:00"
Failed to set time: Automatic time synchronization is enabled
[root@localhost /]# 

禁用NTP后可以修改系统时间：

[root@localhost /]# timedatectl set-ntp no
[root@localhost /]# timedatectl set-time "2019-05-29 11:40:00"
[root@localhost /]# timedatectl status 
      Local time: Wed 2019-05-29 11:40:07 HKT
  Universal time: Wed 2019-05-29 03:40:07 UTC
        RTC time: Wed 2019-05-29 03:40:07
       Time zone: Asia/Hong_Kong (HKT, +0800)
     NTP enabled: no
NTP synchronized: no
 RTC in local TZ: no
      DST active: n/a
[root@localhost /]#