mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-6.repowget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-6.repoyum clean all
yum makecache

mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repowget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repoyum clean all
yum makecache

#卸载redhat资源yum程序rpm -qa | grep yum | xargs rpm -e --nodeps#下载安装软件包wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-3.4.3-168.el7.centos.noarch.rpmwget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-rhn-plugin-2.0.1-10.el7.noarch.rpmwget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.31-54.el7_8.noarch.rpmwget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-metadata-parser-1.1.4-10.el7.x86_64.rpmwget http://mirrors.163.com/centos/7/os/x86_64/Packages/rpm-4.11.3-45.el7.x86_64.rpmwget http://mirrors.163.com/centos/7/os/x86_64/Packages/rpm-libs-4.11.3-45.el7.x86_64.rpmwget http://mirrors.163.com/centos/7/os/x86_64/Packages/rpm-python-4.11.3-45.el7.x86_64.rpmwget http://mirrors.163.com/centos/7/os/x86_64/Packages/rpm-build-libs-4.11.3-45.el7.x86_64.rpmrpm -Uvh rpm-*.rpm#替换.repo文件中的$releasever版本为7sed -i "s/\$releasever/7/g" /etc/yum.repos.d/CentOS-Base.repo
yum install epel-release#检查yum源可用性yum repolist && yum list all#yum update提示"Error: initscripts conflicts with redhat-release-server"yum check-update && yum update --skip-broken