Scenes
[root@localhost bin]# ./mysqld
2020-01-15 17:52:02 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2020-01-15 17:52:02 0 [Note] --secure-file-priv is set to NULL. Operations related to importing and exporting data are disabled
2020-01-15 17:52:02 0 [Note] ./mysqld (mysqld 5.6.44) starting as process 90367 ...
2020-01-15 17:52:02 90367 [Note] Plugin 'FEDERATED' is disabled.
2020-01-15 17:52:02 90367 [Note] InnoDB: Using atomics to ref count buffer pool pages
2020-01-15 17:52:02 90367 [Note] InnoDB: The InnoDB memory heap is disabled
2020-01-15 17:52:02 90367 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2020-01-15 17:52:02 90367 [Note] InnoDB: GCC builtin __atomic_thread_fence() is used for memory barrier
2020-01-15 17:52:02 90367 [Note] InnoDB: Compressed tables use zlib 1.2.11
2020-01-15 17:52:02 90367 [Note] InnoDB: Using Linux native AIO
2020-01-15 17:52:02 90367 [Note] InnoDB: Not using CPU crc32 instructions
2020-01-15 17:52:02 90367 [Note] InnoDB: Initializing buffer pool, size = 128.0M
2020-01-15 17:52:02 90367 [Note] InnoDB: Completed initialization of buffer pool
2020-01-15 17:52:02 90367 [Note] InnoDB: Highest supported file format is Barracuda.
2020-01-15 17:52:02 90367 [Note] InnoDB: 128 rollback segment(s) are active.
2020-01-15 17:52:02 90367 [Note] InnoDB: Waiting for purge to start
2020-01-15 17:52:02 90367 [Note] InnoDB: 5.6.44 started; log sequence number 18755961
2020-01-15 17:52:02 90367 [Note] Server hostname (bind-address): '*'; port: 3306
2020-01-15 17:52:02 90367 [Note] IPv6 is available.
2020-01-15 17:52:02 90367 [Note] - '::' resolves to '::';
2020-01-15 17:52:02 90367 [Note] Server socket created on IP: '::'.
2020-01-15 17:52:02 90367 [ERROR] Can't start server : Bind on unix socket: Address already in use
2020-01-15 17:52:02 90367 [ERROR] Do you already have another mysqld server running on socket: /tmp/mysql.sock ?
2020-01-15 17:52:02 90367 [ERROR] Aborting
Investigation process
1) pipe file already exists
2020-01-15 17:52:02 90367 [ERROR] Can't start server : Bind on unix socket: Address already in use
2020-01-15 17:52:02 90367 [ERROR] Do you already have another mysqld server running on socket: /tmp/mysql.sock ?
2) Check the file properties and viewing the process of occupation
[root@localhost tmp]# file mysqld.sock
mysqld.sock: socket
[root@localhost tmp]# fuser /tmp/mysql.sock
Did not find any process of occupation, stating that the file was not created by mysqld process, and there is no service occupation of the pipeline file, the file is generally used for pipes local mysql server and client end of the communication channel. By default, mysql main process creates when it starts the file, quit when the file is deleted by deleting the file, to solve the above problems.
3) start mysql service, see the occupancy process
[root@localhost tmp]# fuser /tmp/mysql.sock
/tmp/mysqld.sock: 76533
[root@localhost tmp]# lsof /tmp/mysql.sock
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
mysqld 76533 mysql 22u unix 0x00000000f901123c 0t0 8234599 /tmp/mysql.sock