mysql启动不起来

在刚编译安装完成mysql，启动mysql时报了下面错误：

/etc/init.d/mysqld start
Starting MySQL... ERROR! The server quit without updating PID file (/application/mysql-5.6.40/data/ZabbixServer.pid).

显示是没有mysq的pid文件

创建之后还是启动不起来，报上述错误。

查看mysql错误日志：

2018-09-14 08:28:25 2524 [Note] Plugin 'FEDERATED' is disabled.
2018-09-14 08:28:25 2524 [Note] InnoDB: Using atomics to ref count buffer pool pages
2018-09-14 08:28:25 2524 [Note] InnoDB: The InnoDB memory heap is disabled
2018-09-14 08:28:25 2524 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2018-09-14 08:28:25 2524 [Note] InnoDB: Memory barrier is not used
2018-09-14 08:28:25 2524 [Note] InnoDB: Compressed tables use zlib 1.2.3
2018-09-14 08:28:25 2524 [Note] InnoDB: Using Linux native AIO
2018-09-14 08:28:25 2524 [Note] InnoDB: Using CPU crc32 instructions
2018-09-14 08:28:25 2524 [Note] InnoDB: Initializing buffer pool, size = 128.0M
2018-09-14 08:28:25 2524 [Note] InnoDB: Completed initialization of buffer pool
2018-09-14 08:28:25 2524 [Note] InnoDB: Highest supported file format is Barracuda.
2018-09-14 08:28:25 2524 [Note] InnoDB: 128 rollback segment(s) are active.
2018-09-14 08:28:25 2524 [Note] InnoDB: Waiting for purge to start
2018-09-14 08:28:25 2524 [Note] InnoDB: 5.6.40 started; log sequence number 1626087
2018-09-14 08:28:25 2524 [Note] Server hostname (bind-address): '*'; port: 3306
2018-09-14 08:28:25 2524 [Note] IPv6 is available.
2018-09-14 08:28:25 2524 [Note]   - '::' resolves to '::';
2018-09-14 08:28:25 2524 [Note] Server socket created on IP: '::'.
2018-09-14 08:28:25 2524 [ERROR] Can't start server : Bind on unix socket: Permission denie
d
2018-09-14 08:28:25 2524 [ERROR] Do you already have another mysqld server running on socke
t: /application/mysql-5.6.40/tmp/mysql.sock ?
2018-09-14 08:28:25 2524 [ERROR] Aborting

socket套接字没有权限；那就加上权限chmod 777 tmp

重启：/etc/init.d/mysqld start

Starting MySQL. SUCCESS!

启动成功，

提示：遇到错误，首先要学会看报错日志，判断问题出现在什么地方，然后再上网查阅解决办法。