其实memcached源码安装很简单，只要把依赖的libevent安装好了，就万事大吉。
但问题就出在libevent上面
为啥？
安装好之后，总是会报缺失libevent-2.0.so.5模块，memcached无法启动。
先讲这些，开始正式的安装过程。
1，下载软件 http://www.monkey.org/~provos/libevent-2.0.10-stable.tar.gz
2，解压缩验证 tar zxvf libevent-2.0.10-stable.tar.gz
3，安装libevent ./configure && make和make install
4，其实安装到这里已经结束了，并不会出现问题。
但是默认情况下，libevent是安装到了/usr/local/lib目录下，而memcached找ibevent-2.0.so.5模块的路径
却是/usr/lib目录，可想而知，肯定找不到的啊，因此需要你软链接过去，或者你指定安装目录也行。
ln -s /usr/local/lib/libevent-2.0.so.5 /usr/lib/libevent-2.0.so.5
好了，到此为止，才算只真正的安装好了libevent.
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安装memcached其实也很简单。
1，下载文件 http://memcached.googlecode.com/files/memcached-1.4.5.tar.gz
2，解压缩验证 tar zxvf memcached-1.4.5.tar.gz
3，开始安装./configure –prefix=/home/miotour/memcached指定安装目录
make后make test这个时候会发现缺失lib的情况，如果你没有装好的话，之后make install
4，好了，到此为止，memcached已经安装好了，就等你启动了。
5， 启用memcached ./memcached -d -m 100 -p 11211 -u miotour
就是说，在11211端口上，分配100M内存，通过用户miotour来启用后台进程
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还是之前那个问题，报错内容：
# ./memcached -d -m 10 -p 11211 -u miotour
error while loading shared libraries: libevent-2.0.so.5: cannot open shared object file: No such file or directory
查看memcached寻找libevent-2.0.so.5模块的路径
LD_DEBUG=libs ./memcached -v
会有如下结果显示：
以下是引用片段：
[root@localhost memcached-1.2.2]# LD_DEBUG=libs /usr/local/memcached/bin/memcached -v
18999: find library=libevent-1.4.so.2 [0]; searching
18999: search cache=/etc/ld.so.cache
18999: search path=/lib/tls/i686/sse2:/lib/tls/i686:/lib/tls/sse2:/lib/tls:/lib/i686/sse2:/lib/i686:
/lib/sse2:/lib:/usr/lib/tls/i686/sse2:/usr/lib/tls/i686:/usr/lib/tls/sse2:/usr/lib/tls:/usr/lib/i686/sse2:
/usr/lib/i686:/usr/lib/sse2:/usr/lib (system search path)
18999: trying file=/lib/tls/i686/sse2/libevent-1.4.so.2
18999: trying file=/lib/tls/i686/libevent-1.4.so.2
18999: trying file=/lib/tls/sse2/libevent-1.4.so.2
18999: trying file=/lib/tls/libevent-1.4.so.2
18999: trying file=/lib/i686/sse2/libevent-1.4.so.2
18999: trying file=/lib/i686/libevent-1.4.so.2
18999: trying file=/lib/sse2/libevent-1.4.so.2
18999: trying file=/lib/libevent-1.4.so.2
18999: trying file=/usr/lib/tls/i686/sse2/libevent-1.4.so.2
18999: trying file=/usr/lib/tls/i686/libevent-1.4.so.2
18999: trying file=/usr/lib/tls/sse2/libevent-1.4.so.2
18999: trying file=/usr/lib/tls/libevent-1.4.so.2
18999: trying file=/usr/lib/i686/sse2/libevent-1.4.so.2
18999: trying file=/usr/lib/i686/libevent-1.4.so.2
18999: trying file=/usr/lib/sse2/libevent-1.4.so.2
18999: trying file=/usr/lib/libevent-1.4.so.2
18999:
/usr/local/memcached/bin/memcached: error while loading shared libraries: libevent-1.4.so.2: cannot open shared object file: No such file or directory
从上面的内容你可以看到memcached是从哪些路径里面去寻找libevent-1.4.so.2的。
既然知道了他会寻找哪些路径，那你随便找一个路径，软链接过去不就可以了吗
例如 ln -s /usr/local/lib/libevent-1.4.so.2 /usr/lib/libevent-1.4.so.2
重新运行：/usr/local/memcached/bin/memcached -d -m 10 -p 11211 -u root