[20200313]centos 7修改时区.txt

--//无意中检查发现同事安装的linux服务器时区不对.更正过来做一个记录.

--//当前时间是。
# date
Fri Mar 13 16:06:11 EDT 2020

# timedatectl
      Local time: Fri 2020-03-13 16:06:30 EDT
  Universal time: Fri 2020-03-13 20:06:30 UTC
        RTC time: Fri 2020-03-13 16:09:13
       Time zone: America/New_York (EDT, -0400)
     NTP enabled: n/a
NTP synchronized: no
 RTC in local TZ: no
      DST active: yes
 Last DST change: DST began at
                  Sun 2020-03-08 01:59:59 EST
                  Sun 2020-03-08 03:00:00 EDT
 Next DST change: DST ends (the clock jumps one hour backwards) at
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                  Sun 2020-11-01 01:59:59 EDT
                  Sun 2020-11-01 01:00:00 EST
--//tmd:好像还打开类似夏令时的东西.

# timedatectl  set-timezone Asia/Shanghai

# timedatectl
      Local time: Sat 2020-03-14 04:08:11 CST
  Universal time: Fri 2020-03-13 20:08:11 UTC
        RTC time: Fri 2020-03-13 16:10:53
       Time zone: Asia/Shanghai (CST, +0800)
     NTP enabled: n/a
NTP synchronized: no
 RTC in local TZ: no
      DST active: n/a

--//现在时间完全不对
# date
Sat Mar 14 04:11:02 CST 2020

--//最简单就是使用ntpdate与时间服务器同步，检查发现没有安装ntpd,centos 7采用chrony,这个也没有安装
--//只能先手工设置:

# date -s "Fri Mar 13 16:14:11 CST 2020"
Fri Mar 13 16:14:11 CST 2020

--//同步硬件时间。
# hwclock -w ;date
Fri Mar 13 16:17:54 CST 2020

# hwclock ;date
Fri 13 Mar 2020 04:18:19 PM CST  -0.500730 seconds
Fri Mar 13 16:18:19 CST 2020
--//这些应该在安装数据库前仔细检查,实际上这个就是分工带来的麻烦.