一、用Centos镜像搭建本地Yum源
由于安装centos后的默认Yum源为centos的官方地址，所以在国内使用很慢甚至无法访问，所以一般的做法都是把默认的Yum源替换成aliyun的Yum源或者163等国内的Yum源(下文介绍如何配置)。
但是以上的方法都是需要网络的，当没有网络的时候就无法使用了，所以还有一个常用的方法就是用Centos的ISO镜像搭建本地Yum源，这样安装软件的速度就会飞快，缺点是可能有些包没有。
安装Centos后默认的Yum源如下
[root@kangvcar ~]# ll /etc/yum.repos.d/
total 32
-rw-r--r--. 1 root root 1664 Dec 9 2015 CentOS-Base.repo
-rw-r--r--. 1 root root 1309 Dec 9 2015 CentOS-CR.repo
-rw-r--r--. 1 root root 649 Dec 9 2015 CentOS-Debuginfo.repo
-rw-r--r--. 1 root root 290 Dec 9 2015 CentOS-fasttrack.repo
-rw-r--r--. 1 root root 630 Dec 9 2015 CentOS-Media.repo
-rw-r--r--. 1 root root 1331 Dec 9 2015 CentOS-Sources.repo
-rw-r--r--. 1 root root 1952 Dec 9 2015 CentOS-Vault.repo
把默认Yum源备份(可选)
[root@kangvcar ~]# mkdir /opt/centos-yum.bak
[root@kangvcar ~]# mv /etc/yum.repos.d/* /opt/centos-yum.bak/
在虚拟机上挂载CentOS镜像文件
[root@kangvcar ~]# mount -t iso9660 /dev/sr0 /opt/centos
mount: /dev/sr0 is write-protected, mounting read-only
编写repo文件并指向镜像的挂载目录
[root@kangvcar ~]# vi /etc/yum.repos.d/local.repo
[local]
name=local
baseurl=file:///opt/centos
enabled=1
gpgcheck=0
清除缓存
[root@kangvcar ~]# yum clean all
Loaded plugins: fastestmirror
Cleaning repos: local
Cleaning up everything
Cleaning up list of fastest mirrors
[root@kangvcar ~]# yum makecache //把Yum源缓存到本地，加快软件的搜索好安装速度
[root@kangvcar ~]# yum list //列出了3780个包
二、把默认的CentOS Yum源修改成国内的aliyun Yum源
阿里云官方教程：http://mirrors.aliyun.com/help/centos
安装Centos后默认的Yum源如下
[root@kangvcar ~]# ll /etc/yum.repos.d/
total 32
-rw-r--r--. 1 root root 1664 Dec 9 2015 CentOS-Base.repo
-rw-r--r--. 1 root root 1309 Dec 9 2015 CentOS-CR.repo
-rw-r--r--. 1 root root 649 Dec 9 2015 CentOS-Debuginfo.repo
-rw-r--r--. 1 root root 290 Dec 9 2015 CentOS-fasttrack.repo
-rw-r--r--. 1 root root 630 Dec 9 2015 CentOS-Media.repo
-rw-r--r--. 1 root root 1331 Dec 9 2015 CentOS-Sources.repo
-rw-r--r--. 1 root root 1952 Dec 9 2015 CentOS-Vault.repo
把默认Yum源备份(可选)
[root@kangvcar ~]# mkdir /opt/centos-yum.bak
[root@kangvcar ~]# mv /etc/yum.repos.d/* /opt/centos-yum.bak/
下载aliyun Yum源repo文件(对应自己的系统版本下载即可)
#各系统版本repo文件对应的下载操作
CentOS 5
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-5.repo
CentOS 6
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo
CentOS 7
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
[root@kangvcar ~]# cat /etc/redhat-release //查看系统的版本
CentOS Linux release 7.2.1511 (Core)
[root@kangvcar ~]# wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
--2017-06-20 06:43:08-- http://mirrors.aliyun.com/repo/Centos-7.repo
Resolving mirrors.aliyun.com (mirrors.aliyun.com)... 112.124.140.210, 115.28.122.210
Connecting to mirrors.aliyun.com (mirrors.aliyun.com)|112.124.140.210|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 2573 (2.5K) [application/octet-stream]
Saving to: ‘/etc/yum.repos.d/CentOS-Base.repo’
100%[==========] 2,573 --.-K/s in 0s
2017-10-27 06:43:08 (118 MB/s) - ‘/etc/yum.repos.d/CentOS-Base.repo’ saved [2573/2573]
清除缓存
[root@kangvcar ~]# yum clean all
Loaded plugins: fastestmirror
Cleaning repos: base extras updates
Cleaning up everything
Cleaning up list of fastest mirrors
[root@kangvcar ~]# yum makecache //把Yum源缓存到本地，加快软件的搜索好安装速度
[root@kangvcar ~]# yum list //总共列出了9954个包
三、把默认的CentOS Yum源修改成国内的163源
163官方教程：http://mirrors.163.com/.help/centos.html
安装Centos后默认的Yum源如下
[root@kangvcar ~]# ll /etc/yum.repos.d/
total 32
-rw-r--r--. 1 root root 1664 Dec 9 2015 CentOS-Base.repo
-rw-r--r--. 1 root root 1309 Dec 9 2015 CentOS-CR.repo
-rw-r--r--. 1 root root 649 Dec 9 2015 CentOS-Debuginfo.repo
-rw-r--r--. 1 root root 290 Dec 9 2015 CentOS-fasttrack.repo
-rw-r--r--. 1 root root 630 Dec 9 2015 CentOS-Media.repo
-rw-r--r--. 1 root root 1331 Dec 9 2015 CentOS-Sources.repo
-rw-r--r--. 1 root root 1952 Dec 9 2015 CentOS-Vault.repo
把默认Yum源备份(可选)
[root@kangvcar ~]# mkdir /opt/centos-yum.bak
[root@kangvcar ~]# mv /etc/yum.repos.d/* /opt/centos-yum.bak/
下载163 Yum源repo文件
#各系统版本repo文件对应的下载操作
CentOS 5
wget -O /etc/yum.repos.d/CentOS5-Base-163.repo http://mirrors.163.com/.help/CentOS5-Base-163.repo
CentOS 6
wget -O /etc/yum.repos.d/CentOS6-Base-163.repo http://mirrors.163.com/.help/CentOS6-Base-163.repo
CentOS 7
wget -O /etc/yum.repos.d/CentOS7-Base-163.repo http://mirrors.163.com/.help/CentOS7-Base-163.repo
[root@kangvcar ~]# cat /etc/redhat-release //查看系统的版本
CentOS Linux release 7.2.1511 (Core)
[root@kangvcar ~]# wget -O /etc/yum.repos.d/CentOS7-Base-163.repo http://mirrors.163.com/.help/CentOS7-Base-163.repo
--2017-06-20 06:29:47-- http://mirrors.163.com/.help/CentOS7-Base-163.repo
Resolving mirrors.163.com (mirrors.163.com)... 123.58.173.185, 123.58.173.186
Connecting to mirrors.163.com (mirrors.163.com)|123.58.173.185|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1572 (1.5K) [application/octet-stream]
Saving to: ‘/etc/yum.repos.d/CentOS7-Base-163.repo’
100%[=========] 1,572 --.-K/s in 0s
2017-10-27 06:29:47 (293 MB/s) - ‘/etc/yum.repos.d/CentOS7-Base-163.repo’ saved [1572/1572]
清除缓存
[root@kangvcar ~]# yum clean all
Loaded plugins: fastestmirror
Cleaning repos: base extras updates
Cleaning up everything
Cleaning up list of fastest mirrors
[root@kangvcar ~]# yum makecache //把Yum源缓存到本地，加快软件的搜索好安装速度
[root@kangvcar ~]# yum list //总共列出了9951个包
四、修改Yum源的优先级
当既有本地Yum源又有163源的时候，我们在装软件包的时候当然希望先用本地的Yum源去安装，本地找不到可用的包时再使用163源去安装软件,这里就涉及到了优先级的问题，Yum提供的插件yum-plugin-priorities.noarch可以解决这个问题
查看系统是否安装了优先级的插件
[root@kangvcar ~]# rpm -qa | grep yum-plugin-
yum-plugin-fastestmirror-1.1.31-34.el7.noarch
//这里看到没有安装yum-plugin-priorities.noarch这个插件
[root@kangvcar ~]# yum search yum-plugin-priorities
//用search查看是否有此插件可用
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: mirrors.aliyun.com
* extras: mirrors.aliyun.com
* updates: mirrors.aliyun.com
=========== N/S matched: yum-plugin-priorities ===========
yum-plugin-priorities.noarch : plugin to give priorities to packages from different repos
安装yum-plugin-priorities.noarch插件
[root@kangvcar ~]# yum -y install yum-plugin-priorities.noarch
查看插件是否启用
[root@kangvcar ~]# cat /etc/yum/pluginconf.d/priorities.conf
[main]
enabled = 1
//1为启用；0为禁用
修改本地Yum源优先使用
[root@kangvcar ~]# ll /etc/yum.repos.d/
total 8
-rw-r--r--. 1 root root 2573 May 15 2015 CentOS-Base.repo
-rw-r--r--. 1 root root 67 Jun 20 06:04 local.repo
//有两个repo文件
[root@kangvcar ~]# vi /etc/yum.repos.d/local.repo
[local]
name=local
baseurl=file:///opt/centos
enabled=1
gpgcheck=0
priority=1
//在原基础上加入priority=1 ；数字越小优先级越高
//可以继续修改其他源的priority值，经测试仅配置本地源的优先级为priority=1就会优先使用本地源了
测试
配置优先级前：(使用阿里云Yum源)
[root@kangvcar ~]# yum -y install vim
Dependencies Resolved
Package Arch Version Repository Size
Installing:
vim-enhanced x86_64 2:7.4.160-1.el7_3.1 updates 1.0 M
Updating for dependencies:
vim-common x86_64 2:7.4.160-1.el7_3.1 updates 5.9 M
省略...
配置优先级后：(使用本地Yum源)
[root@kangvcar ~]# yum -y install vim
Dependencies Resolved
Package Arch Version Repository Size
Installing:
vim-enhanced x86_64 2:7.4.160-1.el7 local 1.0 M
Installing for dependencies:
gpm-libs x86_64 1.20.7-5.el7 local 32 k
perl x86_64 4:5.16.3-286.el7 local 8.0 M
perl-Carp noarch 1.26-244.el7 local 19 k
perl-Encode x86_64 2.51-7.el7 local 1.5 M
perl-Exporter noarch 5.68-3.el7 local 28 k
perl-File-Path noarch 2.09-2.el7 local 26 k
perl-File-Temp noarch 0.23.01-3.el7 local 56 k
省略...