错误描述：

#yum install php-mcrypt

Setting up Install Process

No package php-mcrypt available.
Error: Nothing to do

我们会看到centos yum从仓库中根本找不到这几个包。

yum  install epel-release  //扩展包更新包

# yum install php-mcrypt

Loaded plugins: fastestmirror, security
Loading mirror speeds from cached hostfile
Error: Cannot retrieve metalink for repository: epel. Please verify its path and try again

 编辑vi /etc/yum.repos.d/epel.repo，如下

#baseurl
mirrorlist
改成
baseurl
#mirrorlist

#yum install php-mcrypt