linux 报错：E: Package 'libmemcached' has no installation candidate
网上查资料说是软件安装源没有这个软件，需要添加软件源。
1.备份源列表
sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak
2.添加源列表
在这个网站上选择适合你的版本型号的源列表（一定要选对版本）
http://wiki.ubuntu.org.cn/Qref/Source#Hardy.288.04.29_.E7.89.88.E6.9C.AC。
3.刷新列表
sudo apt-get update
sudo apt-get upgrade
以上是网上搜到的资料，说是很多都那样解决了，
但是尝试了如下一堆的软件源还是没有成功安装memcached的客户端libmemcached。
deb http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiversei deb http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse deb http://cn.archive.ubuntu.com/ubuntu/ trusty main restricted universe multiverse deb http://cn.archive.ubuntu.com/ubuntu/ trusty-security main restricted universe multiverse deb http://cn.archive.ubuntu.com/ubuntu/ trusty-updates main restricted universe multiverse deb http://cn.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty main restricted universe multiverse deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty-security main restricted universe multiverse deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty-updates main restricted universe multiverse deb-src http://cn.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse deb http://archive.canonical.com/ubuntu/ trusty partner deb http://extras.ubuntu.com/ubuntu/ trusty main deb http://archive.ubuntu.com/ubuntu trusty-backports main restricted universe multiverse deb-src http://archive.ubuntu.com/ubuntu trusty-backports main restricted universe multiverse deb http://security.ubuntu.com/ubuntu trusty-security main restricted deb-src http://security.ubuntu.com/ubuntu trusty-security main restricted deb http://security.ubuntu.com/ubuntu trusty-security universe deb-src http://security.ubuntu.com/ubuntu trusty-security universe deb http://security.ubuntu.com/ubuntu trusty-security multiverse deb-src http://security.ubuntu.com/ubuntu trusty-security multiverse
暂时不使用apt-get方式安装libmemcached，换用编译安装的方式。
1. 下载libmemcached，当前最新版本：libmemcached-1.0.18.tar.gz，官网：https://launchpad.net/libmemcached/
wget https://launchpad.net/libmemcached/1.0/1.0.18/+download/libmemcached-1.0.18.tar.gz
2.解压
tar zxvf libmemcached-1.0.18.tar.gz
3.进入目录
cd libmemcached-1.0.18/
4.编译安装
./configure make sudo make install