yum install libevent libevent-devel libmemcached libmemcached-devel
    (libmemcached-devel:error: yum设置epel源：yum install https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm)

    设置国内yum源https://blog.csdn.net/zhaluo_dehezi/article/details/86689322
    centos8问题：https://blog.csdn.net/doubleface999/article/details/108836126
    1.安装

    1. tar -zxvf memcached.tar.gz
    2. cd memcached
    3. ./configure --prefix=/usr/local/memcached

    2.启动

    1. /usr/local/memcached -d -u nobody -l localhost -m 1024 -p 11211