一，备份源文件：
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak
二、建立修改源文件
cd /etc/yum.repos.d/vi CentOS-Base.repo替换里面的CentOS-Base.repo
# 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.
[os]
name=Qcloud centos os - $basearch
baseurl=http://mirrors.cloud.tencent.com/centos/$releasever/os/$basearch/
enabled=1
gpgcheck=1
gpgkey=http://mirrors.cloud.tencent.com/centos/RPM-GPG-KEY-CentOS-7
[updates]
name=Qcloud centos updates - $basearch
baseurl=http://mirrors.cloud.tencent.com/centos/$releasever/updates/$basearch/
enabled=1
gpgcheck=1
gpgkey=http://mirrors.cloud.tencent.com/centos/RPM-GPG-KEY-CentOS-7
[centosplus]
name=Qcloud centosplus - $basearch
baseurl=http://mirrors.cloud.tencent.com/centos/$releasever/centosplus/$basearch/
enabled=0
gpgcheck=1
gpgkey=http://mirrors.cloud.tencent.com/centos/RPM-GPG-KEY-CentOS-7
[cr]
name=Qcloud centos cr - $basearch
baseurl=http://mirrors.cloud.tencent.com/centos/$releasever/cr/$basearch/
enabled=0
gpgcheck=1
gpgkey=http://mirrors.cloud.tencent.com/centos/RPM-GPG-KEY-CentOS-7
[extras]
name=Qcloud centos extras - $basearch
baseurl=http://mirrors.cloud.tencent.com/centos/$releasever/extras/$basearch/
enabled=1
gpgcheck=1
gpgkey=http://mirrors.cloud.tencent.com/centos/RPM-GPG-KEY-CentOS-7
[fasttrack]
name=Qcloud centos fasttrack - $basearch
baseurl=http://mirrors.cloud.tencent.com/centos/$releasever/fasttrack/$basearch/
enabled=0
gpgcheck=1
gpgkey=http://mirrors.cloud.tencent.com/centos/RPM-GPG-KEY-CentOS-7
三、清除原缓存
yum clean all
四、创建新缓存
yum makecache
