[root@localhost mysql]# /etc/init.d/mysqld start
Starting MySQL...... ERROR! Manager of pid-file quit without updating file.


下面是错误日志
[root@localhost mysql]# cat /data/mysql/localhost.err 
151229 11:28:34 mysqld_safe Starting mysqld daemon with databases from /data/mysql
151229 11:28:34 [Warning] '--skip-locking' is deprecated and will be removed in a future release. Please use '--skip-external-locking' instead.
151229 11:28:34 [Note] Plugin 'FEDERATED' is disabled.
InnoDB: The first specified data file ./ibdata1 did not exist:
InnoDB: a new database to be created!
151229 11:28:34 InnoDB: Setting file ./ibdata1 size to 10 MB
InnoDB: Database physically writes the file full: wait...
151229 11:28:34 InnoDB: Log file ./ib_logfile0 did not exist: new to be created
InnoDB: Setting log file ./ib_logfile0 size to 5 MB
InnoDB: Database physically writes the file full: wait...
151229 11:28:34 InnoDB: Log file ./ib_logfile1 did not exist: new to be created
InnoDB: Setting log file ./ib_logfile1 size to 5 MB
InnoDB: Database physically writes the file full: wait...
InnoDB: Doublewrite buffer not found: creating new
InnoDB: Doublewrite buffer created
InnoDB: Creating foreign key constraint system tables
InnoDB: Foreign key constraint system tables created
151229 11:28:34 InnoDB: Started; log sequence number 0 0
151229 11:28:34 [ERROR] Can't start server: Bind on TCP/IP port: Address already in use
151229 11:28:34 [ERROR] Do you already have another mysqld server running on port: 3306 ?
151229 11:28:34 [ERROR] Aborting

151229 11:28:34 InnoDB: Starting shutdown...
151229 11:28:39 InnoDB: Shutdown completed; log sequence number 0 44233
151229 11:28:39 [Note] /usr/local/mysql/bin/mysqld: Shutdown complete

151229 11:28:39 mysqld_safe mysqld from pid file /data/mysql/localhost.pid ended

解决办法:kill掉占用3306端口的进程。