service mysql start
报错：
Starting MySQL. ERROR! The server quit without updating PID file（xxx/x.pid）
查看日志：
[ERROR] Could not create unix socket lock file /usr/local/mysql/sock/mysql.sock.lock.
2018-11-30T03:01:12.764913Z 0 [ERROR] Unable to setup unix socket lock file.
2018-11-30T03:01:12.764928Z 0 [ERROR] Aborting
原因：
mysql用户没有/usr/local/mysql/sock/权限
解决办法：
chown -R mysql.mysql /usr/local/mysql/sock/