添加Epel源:

方法一：
sudo yum install epel-release -y        
方法二：
sudo yum install https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm         
sudo yum install https://dl.fedoraproject.org/pub/epel/epel-release-latest-6.noarch.rpm
注：
1.
安装后执行yum install soft-package -y报
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
Error: Cannot retrieve Metalink for repository: epel. Please verify its path and try again
或
Peer cert cannot be verified or peer cert invalid；
解决方法：添加 "sslverify=false" 到 /etc/yum.conf

添加Elrepo源：

sudo rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org     
sudo rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm  
sudo rpm -Uvh http://www.elrepo.org/elrepo-release-6-6.el6.elrepo.noarch.rpm

添加Rpmforge源：

http://www.rpm-find.net/linux/RPM/apt.sw.be/redhat/el6/en/x86_64/rpmforge/RPMS/rpmforge-release-0.5.3-1.el6.rf.x86_64.html       
http://rpmfind.net/linux/RPM/dag/redhat/el6/x86_64/rpmforge-release-0.5.3-1.el6.rf.x86_64.html  
直接搜索对应的软件包，下方软件包链接失效
rpm -Uvh ftp://ftp.pbone.net/mirror/apt.sw.be/redhat/el6/en/x86_64/rpmforge/RPMS/rpmforge-release-0.5.3-1.el6.rf.x86_64.rpm

添加Remi源：

rpm -Uvh http://rpms.famillecollet.com/enterprise/remi-release-7.rpm        
rpm -Uvh http://rpms.famillecollet.com/enterprise/remi-release-6.rpm

添加IUS repo源：

sudo yum install epel-release       
sudo rpm -Uvh https://centos7.iuscommunity.org/ius-release.rpm      
sudo rpm -Uvh https://centos6.iuscommunity.org/ius-release.rpm

添加Webtatic源：

rpm -Uvh http://rpms.famillecollet.com/enterprise/remi-release-7.rpm        
rpm -Uvh http://repo.webtatic.com/yum/el7/webtatic-release.rpm      
rpm -Uvh http://rpms.famillecollet.com/enterprise/remi-release-6.rpm        
rpm -Uvh http://repo.webtatic.com/yum/el6/latest.rpm

#search it      
sudo yum search htop

#get more info,if found        
sudo yum info htop
 
#install it     
sudo yum install htop