centos7系统时间校准与同步

#!/bin/bash

# ########## 脚本执行参数 #########
# 时间同步服务器地址
time_sync_domain="cn.pool.ntp.org"
# 时间同步服务器ip地址
time_sync_ip="172.28.72.81"
# 更新命令
sync_cmd="ntpdate"
###################################

# 删除定时更新命令到crontab
sed -i '/'${sync_cmd}'/d' /etc/crontab

# 删除时间同步服务器dns
sed -i '/'${time_sync_domain}'/d' /etc/hosts

# 安装时间同步服务
yum install -y ntp
systemctl enable ntpd
systemctl start ntpd
timedatectl set-timezone Asia/Shanghai
echo "OPTIONS=\"-g -x\"" > /etc/sysconfig/ntpd
/bin/systemctl restart ntpd.service

# 添加时间同步服务器dns
result=`cat /etc/hosts | grep ${time_sync_domain}`
if [ x"${result}" == x"" -a x"${time_sync_ip}" != x"" ];then
echo "${time_sync_ip} ${time_sync_domain}" >> /etc/hosts
fi

# 更新系统时间
ntpdate -u ${time_sync_domain}

# 添加定时更新命令到crontab
result=`cat /etc/crontab | grep ${sync_cmd}`
if [ x"${result}" = x"" ];then
echo "30 1 * * * root ${sync_cmd} -u ${time_sync_domain};hwclock --systohc" >> /etc/crontab
fi