[root@localhost yum]# yum update Loaded plugins: fastestmirror, refresh-packagekit, security 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 Repository contrib is listed more than once in the configuration Determining fastest mirrors epel/metalink | 4.6 kB 00:00 * epel: mirrors.yun-idc.com * rpmforge: mirrors.neusoft.edu.cn http://mirrors.163.com/centos/$releasever/os/i386/repodata/repomd.xml: [Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404 Not Found" Trying other mirror. Error: Cannot retrieve repository metadata (repomd.xml) for repository: base. Please verify its path and try again [root@localhost yum]# vi /etc/yum.conf [root@localhost yum]# yum update -y Loaded plugins: fastestmirror, refresh-packagekit, security 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 Repository contrib is listed more than once in the configuration Loading mirror speeds from cached hostfile epel/metalink | 4.6 kB 00:00 * epel: mirrors.yun-idc.com * rpmforge: mirrors.neusoft.edu.cn base | 3.7 kB 00:00 extras | 3.5 kB 00:00 rpmforge
输入下面的命令即可解决问题：
yum clean all
yum makecache