epel的安装以及yum的使用

epel是软件包的镜像源，用于配合yum进行Centos下软件的安装。

epel镜像源的安装

首先备份原镜像源,通常原镜像源位于 /etc/yum.repos.d/目录下：

mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup

建议安装阿里云的epel镜像源，命令如下：

wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo 

安装成功依次进行清理和生成缓存命令。

yum clean all
yum makecache

至此可以使用新的镜像源利用yum进行软件安装。

yum的使用

非常便捷的安装工具，以安装r为例：

yum install R

安装成功后，输入大写的R即可进入R环境下：

R

R的经典启动页面就会显示到屏幕上：

R version 3.5.2 (2018-12-20) -- "Eggshell Igloo"
Copyright (C) 2018 The R Foundation for Statistical Computing
Platform: x86_64-redhat-linux-gnu (64-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

  Natural language support but running in an English locale

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.