**centos默認的安裝源在官方centos.org上,而redis在第三方的yum源裏,因此沒法安裝redis
1. 首先爲yum添加epel源centos
yum install epel-release
2. 而後安裝rediscode
yum install redis
3. 啓動redis服務class
systemctl start redis