ERROR! MariaDB is running but PID file could not be found

在CentOS7.6上安装了MariaDB10.3，采用的yum方式安装的，用命令查看数据库的状态会报错误

[root@centos7 ~]# service mysql status
 ERROR! MariaDB is running but PID file could not be found

在配置文件/etc/my.cnf中增加一行，pid_file=/var/lib/mysql/centos7.pid
然后在查询mysql的状态，正常！

[root@centos7 ~]# service mysql status
 SUCCESS! MariaDB running (3867)