centos7手动更新源

centos7默认最小化安装，所以很多的软件没有，然而系统自带的是国外的源，所以必须要更新国内的源，打开
http://mirrors.163.com/.help/centos.html
选择centos7,下载的文件中有如下的内容

# CentOS-Base.repo## The mirror system uses the connecting IP address of the client and the# update status of each mirror to pick mirrors that are updated to and# geographically close to the client.  You should use this for CentOS updates# unless you are manually picking other mirrors.## If the mirrorlist= does not work for you, as a fall back you can try the # remarked out baseurl= line instead.##[base]name=CentOS-$releasever - Base - 163.com#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=osbaseurl=http://mirrors.163.com/centos/$releasever/os/$basearch/gpgcheck=1gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7#released updates[updates]name=CentOS-$releasever - Updates - 163.com#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updatesbaseurl=http://mirrors.163.com/centos/$releasever/updates/$basearch/gpgcheck=1gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7#additional packages that may be useful[extras]name=CentOS-$releasever - Extras - 163.com#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extrasbaseurl=http://mirrors.163.com/centos/$releasever/extras/$basearch/gpgcheck=1gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7#additional packages that extend functionality of existing packages[centosplus]name=CentOS-$releasever - Plus - 163.combaseurl=http://mirrors.163.com/centos/$releasever/centosplus/$basearch/gpgcheck=1enabled=0gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7

在/etc/目录下创建CentOS-Base.repo这个文件（一般都有，但是我这里不知道为什么没有了），然后把前面网站上下载的文件中的内容黏贴过来，保存

yum clean all

yum makecache