一、yum源简介
Yum（全称为 Yellow dog Updater, Modified）是一个在Fedora和RedHat以及CentOS中的Shell前端软件包管理器。基于RPM包管理，能够从指定的服务器自动下载RPM包并且安装，可以自动处理依赖性关系，并且一次安装所有依赖的软件包，无须繁琐地一次次下载、安装。 （来自百度百科）
默认yum源为CentOS官方源：mirrorlist.centos.org。
因其服务器在国外，直接从官方源下载安装软件时稳定性、速度等有时并不是很好，国内有如阿里云源、网易源等镜像站点，比官方源更稳定、速度更快。
二、yum安装软件命令
安装软件(以foo-x.x.x.rpm为例）：yum install foo-x.x.x.rpm
删除软件：yum remove foo-x.x.x.rpm或者yum erase foo-x.x.x.rpm
升级软件：yum update foo或者yum update foo
查询信息：yum info foo
三、修改yum源为阿里云
3.1 yum源配置文件路径：
/etc/yum.repos.d/CentOS-Base.repo
3.2 查看CentOS-Base.repo文件内容：
cat /etc/yum.repos.d/CentOS-Base.repo
root@sheng yum.repos.d\]# cat 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. # # \[base
name=CentOS-$releasever - Base - mirrors.aliyun.com
failovermethod=priority
baseurl=http://mirrors.aliyun.com/centos/$releasever/os/$basearch/
http://mirrors.aliyuncs.com/centos/$releasever/os/$basearch/
http://mirrors.cloud.aliyuncs.com/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
#released updates
updates
name=CentOS-$releasever - Updates - mirrors.aliyun.com
failovermethod=priority
baseurl=http://mirrors.aliyun.com/centos/$releasever/updates/$basearch/
http://mirrors.aliyuncs.com/centos/$releasever/updates/$basearch/
http://mirrors.cloud.aliyuncs.com/centos/$releasever/updates/$basearch/
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
#additional packages that may be useful
extras
name=CentOS-$releasever - Extras - mirrors.aliyun.com
failovermethod=priority
baseurl=http://mirrors.aliyun.com/centos/$releasever/extras/$basearch/
http://mirrors.aliyuncs.com/centos/$releasever/extras/$basearch/
http://mirrors.cloud.aliyuncs.com/centos/$releasever/extras/$basearch/
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
#additional packages that extend functionality of existing packages
centosplus
name=CentOS-$releasever - Plus - mirrors.aliyun.com
failovermethod=priority
baseurl=http://mirrors.aliyun.com/centos/$releasever/centosplus/$basearch/
http://mirrors.aliyuncs.com/centos/$releasever/centosplus/$basearch/
http://mirrors.cloud.aliyuncs.com/centos/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
#contrib - packages by Centos Users
contrib
name=CentOS-$releasever - Contrib - mirrors.aliyun.com
failovermethod=priority
baseurl=http://mirrors.aliyun.com/centos/$releasever/contrib/$basearch/
http://mirrors.aliyuncs.com/centos/$releasever/contrib/$basearch/
http://mirrors.cloud.aliyuncs.com/centos/$releasever/contrib/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
root@sheng yum.repos.d\]# 3.3 备份官方源配置： cp /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak 3.4 下载阿里云yum源配置文件覆盖原官方源配置文件： curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo 此时该文件（ /etc/yum.repos.d/CentOS-Base.repo）已是阿里云yum源配置文件，可用 cat /etc/yum.repos.d/CentOS-Base.repo 查看文件内容。 3.5 清理缓存并生成新的缓存： yum clean all yum makecache 3.6 更新软件 sudo yum -y update 完 注意：如果Linux 机器中没有CURL 命令，可以COPY 项目aliyun 上面repo 的内容。