repos.d/etc/yum.repos.d.backup2。设置一个新的yum目录mkdir/etc/yum.repos.d3。安装wget（我没安装，没关系，可能我之前安装过）yuminstall-ywget4。被下载配置坑了一晚上（一定要区分自己的系统版本，不然肯定过不了）CentOS5wget-O/etc/yum.repos.d/CentOS-Base.repohttp://mirrors.aliyun.com/repo/Centos-5.repoCentOS6wget-O/etc/yum.repos.d/CentOS-Base.repohttp://mirrors.aliyun.com/repo/Centos-6.repoCentOS7wget-O/etc/百胜。repos.d/CentOS-Base.repohttp://mirrors.aliyun.com/repo/Centos-7.repoCentOS8wget-O/etc/yum.repos.d/CentOS-Base.repohttp://mirrors.aliyun.com/repo/Centos-8.repo5。清除文件并重建元数据缓存yumcleanallyummakecache6。最后更新软件包，这一步需要下载安装或者升级软件包，比较费时间！百胜更新-y
