更改CentOS7 yum源

方法一：更改相关文件

（1）先将yum源文件备份

cp CentOS-Base.repo CentOs-Base.repo.backup

（2）转到yum源目录，便于下一步操作

cd /etc/yum.repos.d

（3）更改配置文件

vi CentOS-Base.repo	

将文件中的内容改为下面的代码

# 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=$basearch&repo=os
baseurl=http://mirrors.163.com/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=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=$basearch&repo=updates
baseurl=http://mirrors.163.com/centos/$releasever/updates/$basearch/
gpgcheck=1
gpgkey=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=$basearch&repo=extras
baseurl=http://mirrors.163.com/centos/$releasever/extras/$basearch/
gpgcheck=1
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7

#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus - 163.com
baseurl=http://mirrors.163.com/centos/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7

方法二：将国外镜像源改为国内的

（1）首先还是将文件备份

cp CentOS-Base.repo CentOs-Base.repo.backup

（2）转到相关目录

cd /etc/yum.repos.d

（3） 更换yum源        //我这里是将镜像源切换成了阿里云镜像源

sudo curl-o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/CentOS-7.repo

相关镜像源还有

阿里云开源镜像站：阿里巴巴开源镜像站-OPSX镜像站-阿里云开发者社区阿里巴巴开源镜像站，免费提供Linux镜像下载服务，拥有Ubuntu、CentOS、Deepin、MongoDB、Apache、Maven、Composer等多种开源软件镜像源，此外还提供域名解析DNS、网络授时NTP等服务，致力于为互联网用户提供全面，高效和稳定的基础服务。https://mirrors.aliyun.com/

网易开源镜像站：欢迎访问网易开源镜像站https://mirrors.163.com/

中科大开源镜像站：USTC Open Source Software Mirrorhttps://mirrors.ustc.edu.cn/

清华开源镜像站：清华大学开源软件镜像站 | Tsinghua Open Source Mirror清华大学开源软件镜像站，致力于为国内和校内用户提供高质量的开源软件镜像、Linux 镜像源服务，帮助用户更方便地获取开源软件。本镜像站由清华大学 TUNA 协会负责运行维护。https://mirrors.tuna.tsinghua.edu.cn/

（4）清除旧的yum缓存

yum clean all

（5）生成新的yum缓存

yum makecache

（6）更新软件包

yum update -y

关于yum的一些指令（以下载nginx为例）

yum install epel-release -y    #yum安装拓展yum仓库

yum install nginx -y    #下载

yum remove ngnix -y    #卸载

yum repolist    #查看rpm的数量