Centos7安装后修改yum和epel源

cd /etc/yum.repos.d/
mkdir repo_bak
mv *.repo repo_bak/

wget http://mirrors.aliyun.com/repo/Centos-7.repo
wget http://mirrors.163.com/.help/CentOS7-Base-163.repo
ls
#结果显示
Centos-7.repo  CentOS-Base-163.repo  repo.bak

yum clean all #清除所有的缓存
#结果显示
Loaded plugins: fastestmirror
Repository base is listed more than once in the configuration
Repository updates is listed more than once in the configuration
Repository extras is listed more than once in the configuration
Repository centosplus is listed more than once in the configuration
Cleaning repos: base extras updates
Cleaning up list of fastest mirrors
yum makecache #生成yum缓存

yum list | grep epel-release
Repository base is listed more than once in the configuration
Repository updates is listed more than once in the configuration
Repository extras is listed more than once in the configuration
Repository centosplus is listed more than once in the configuration
epel-release.noarch                       7-11                        extras 
yum install -y epel-release
#结果显示

# 下载阿里开源镜像的epel源文件
wget -O /etc/yum.repos.d/epel-7.repo http://mirrors.aliyun.com/repo/epel-7.repo 

yum repolist enabled #查询可用的源
yum repolist all#查询所有的源

yum -y update

yum -y install cronie
yum -y install yum-cron

/etc/cron.daily/0yum.cron
#每天执行这个档案一次，它根据配置档案 /etc/yum/yum-cron.conf 来更新软件
/etc/yum/yum-cron.conf
#这是每天执行yum-cron的配置档案，默认只会下载更新的软件，并不安装，用意是让管理员检视yum-cron的输出，选取需要更新的软件进行手动安装。

vim /etc/yum/yum-cron.conf

apply_updates=no 
#修改为
apply_updates=yes
#确认一下参数一致
update_messages=yes
download_updates=yes
apply_updates=yes

systemctl start crond
systemctl start yum-cron

yum install firewalld

firewall-cmd --list-all