An Error Was Encountered
The Encrypt library requires the Mcrypt extension.

CI 框架 缺少 mcrypt 扩展

yum 安装 mcrypt

yum install libmcrypt libmcrypt-devel mcrypt mhash

源码编译没试，可参考这篇文章 

安装 php 的 mcrypt 扩展

扩展在 php 安装包的 ext 目录下

[root@instance-jewlel2q ~]# cd php-5.6.30/
[root@instance-jewlel2q php-5.6.30]# cd ext/mcrypt/
[root@instance-jewlel2q mcrypt]# /usr/local/php5/bin/phpize 

返回

Configuring for:
PHP Api Version:         20131106
Zend Module Api No:      20131226
Zend Extension Api No:   220131226

[root@instance-jewlel2q mcrypt]# ./configure --with-php-config=/usr/local/php5/bin/php-config

返回

creating libtool
appending configuration tag "CXX" to libtool
configure: creating ./config.status
config.status: creating config.h

编译

[root@instance-jewlel2q mcrypt]# make
[root@instance-jewlel2q mcrypt]# make install
Installing shared extensions:     /usr/local/php5/lib/php/extensions/no-debug-non-zts-20131226/

查看扩展目录

[root@instance-jewlel2q mcrypt]# cd  /usr/local/php5/lib/php/extensions/no-debug-non-zts-20131226/
[root@instance-jewlel2q no-debug-non-zts-20131226]# ll
total 2092
-rwxr-xr-x 1 root root  170080 Nov  1 17:02 mcrypt.so
-rwxr-xr-x 1 root root 1340288 Nov  1 14:59 opcache.a
-rwxr-xr-x 1 root root  623648 Nov  1 14:59 opcache.so

安装成功

向 php.ini 写入扩展目录

vim /usr/local/php5/lib/php.ini

重启，查看 phpinfo

采坑记录

php 的配置文件应放在 lib 目录下，自己在 ext 目录下一直不生效，换到 lib 目录下重载后生效了

PHP

function click($id){
	$this->db->where(array('id'=>$id));
	$this->db->set('click','click + 1',FALSE);
	$this->db->update('table');
}