CentOS通过yum安装Mariadb(MySQL)无法启动服务或者找不到mysql.sock(2)

今天在Linux主机（CentOS 7）安装（yum install方式）Mariadb（即开源MySQL）后，无法启动mariadb，其实是安装不完整，当然启动不了，更不用说输入
#mysql -u root
提示
Can’t connect to local MySQL server through socket ‘/tmp/mysql.sock’ (2)

安装mariadb，先搜索一发：
#yum search mariadb
出现：

#yum search mariadbLoaded plugins: langpacks============================= N/S matched: mariadb =============================mariadb-bench.x86_64 : MariaDB benchmark scripts and datamariadb-devel.i686 : Files for development of MariaDB/MySQL applicationsmariadb-devel.x86_64 : Files for development of MariaDB/MySQL applicationsmariadb-embedded.i686 : MariaDB as an embeddable librarymariadb-embedded.x86_64 : MariaDB as an embeddable librarymariadb-embedded-devel.i686 : Development files for MariaDB as an embeddable : librarymariadb-embedded-devel.x86_64 : Development files for MariaDB as an embeddable  : librarymariadb-libs.i686 : The shared libraries required for MariaDB/MySQL clientsmariadb-libs.x86_64 : The shared libraries required for MariaDB/MySQL clientsmariadb-server.x86_64 : The MariaDB server and related filesmariadb.x86_64 : A community developed branch of MySQLmariadb-test.x86_64 : The test suite distributed with MariaD

嗯，把 mariadb mariadb-bench mariadb-server mariadb-embdedeb mariadb-libs都安装：
#yum install mariadb-embedded mariadb-libs mariadb-bench mariadb mariadb-server -y

先启动（service命令就不要用了）

# systemctl start mariadb

开机启动

$ systemctl enable mariadb