转：https://www.liquidweb.com/kb/how-to-install-memcached-on-centos-7/

http://devdocs.magento.com/guides/v2.0/config-guide/memcache/memcache_centos.html

评注：

1. 写的非常好。清晰易懂，

Install and configure memcached on CentOS

This section provides instructions to install memcached on CentOS and Ubuntu. For additional information, consult the memcached wiki.

To install memcached on CentOS, perform the following tasks as a user with root privileges:

1. Install memcached and its dependencies:

   yum -y update
   
   yum install -y libevent libevent-devel
   
   yum install -y memcached
   
   yum install -y php-pecl-memcache
   

   The syntax of the preceding commands might depend on what package repositories you use. For example, if you use webtatic and PHP 5.6, enter yum install -y php56w-pecl-memcache. Use yum search memcache|grep php to find the appropriate package name.

2. Change the memcached configuration setting for CACHESIZE and OPTIONS:

   1. Open /etc/sysconfig/memcached in a text editor.

   2. Locate the value for CACHESIZE and change it to at least 1GB.

      For example,

      CACHESIZE="1GB"
      

   3. Locate the value for OPTIONS and change it to localhost or 127.0.0.1

   For more information about configuring memcached, see the memcached wiki.

3. Save your changes to memcached and exit the text editor.

4. Restart memcached.

   service memcached restart
   

5. Restart your web server.

   For Apache, service httpd restart

6. Continue with the next section.