查询卸载已安装PHP
sudo aptitude purge dpkg -l | grep php| awk '{print $2}' |tr "\n" " "

2.通过ppa安装
sudo add-apt-repository ppa:ondrej/php

sudo apt-get update
sudo apt-get install php5.6或者sudo apt-get install php5.6-fpm php5.6-cli php5.6-mcrypt

4.配置PHP
sudo vim /etc/php/5.6/fpm/php.ini

打开PHP配置文件，找到cgi.fix_pathinfo选项，去掉它前面的注释分号;，然后将它的值设置为0,如下
cgi.fix_pathinfo=0

5.启用php5-mcrypt:

sudo phpenmod mcrypt

6.重启php5-fpm:

sudo service php5.6-fpm restart