Mysql服务启动错误之(MySQL manager or server PID file could not be found)
对于类似的错误，网上很多，但是多归多，找到解决思路的方法才是最为重要的！现在我们来看，当我执行
[root@cacti init.d]# service mysqld start
Starting MySQL................................... [FAILED]
无法启动，/etc/init.d/mysqld start仍然无法启动，对于无法启动，或者其他异常的信息出现时，我们首先应该找到错误，通过什么，日志，是一个有力的反馈给我的信息捷径。。
于是，到/usr/local/mysql/var/查看日志文件*.err的文件，我们vim编辑看下里面的内容
120919 17:19:31 mysqld started
120919 17:19:31 InnoDB: Started; log sequence number 0 43655
120919 17:19:31 [Note] /usr/local/mysql/libexec/mysqld: ready for connections.
Version: '5.0.22-log' socket: '/tmp/mysql.sock' port: 3306 Source distribution
120919 17:41:09 [Note] /usr/local/mysql/libexec/mysqld: Normal shutdown
120919 17:41:09 InnoDB: Starting shutdown...
120919 17:41:11 InnoDB: Shutdown completed; log sequence number 0 43655
120919 17:41:11 [Note] /usr/local/mysql/libexec/mysqld: Shutdown complete
120919 17:41:11 mysqld ended
120919 17:41:12 mysqld started
^G/usr/local/mysql/libexec/mysqld: File './mysql-bin.index' not found (Errcode: 13)
120919 17:41:12 [ERROR] Aborting
120919 17:41:12 [Note] /usr/local/mysql/libexec/mysqld: Shutdown complete
120919 17:41:12 mysqld ended
120919 17:42:07 mysqld started
^G/usr/local/mysql/libexec/mysqld: File './mysql-bin.index' not found (Errcode: 13)
120919 17:42:07 [ERROR] Aborting
^G/usr/local/mysql/libexec/mysqld: File './mysql-bin.index' not found (Errcode: 13)
120919 17:41:12 [ERROR] Aborting
120919 17:41:12 [Note] /usr/local/mysql/libexec/mysqld: Shutdown complete
120919 17:41:12 mysqld ended
120919 17:42:07 mysqld started
^G/usr/local/mysql/libexec/mysqld: File './mysql-bin.index' not found (Errcode: 13)
120919 17:42:07 [ERROR] Aborting
120919 17:42:07 [Note] /usr/local/mysql/libexec/mysqld: Shutdown complete
120919 17:42:07 mysqld ended
120919 17:42:54 mysqld started
^G/usr/local/mysql/libexec/mysqld: File './mysql-bin.index' not found (Errcode: 13)
120919 17:42:54 [ERROR] Aborting
120919 17:42:54 [Note] /usr/local/mysql/libexec/mysqld: Shutdown complete
120919 17:42:54 mysqld ended
120919 17:43:57 mysqld started
^G/usr/local/mysql/libexec/mysqld: File './mysql-bin.index' not found (Errcode: 13)
120919 17:43:57 [ERROR] Aborting
120919 17:43:57 [Note] /usr/local/mysql/libexec/mysqld: Shutdown complete
120919 17:43:57 mysqld ended
120919 17:51:30 mysqld started
^G/usr/local/mysql/libexec/mysqld: File './mysql-bin.index' not found (Errcode: 13)
120919 17:51:30 [ERROR] Aborting
看到红色错误了吗？是找不到mysql-bin.index文件，当我退出编辑状态，回到/usr/local/mysql/var目录下可以明细看到又该文件！以下为信息
[root@cacti var]# ll
total 21880
drwx------ 2 root mysql 12288 Sep 19 16:42 cactidb
-rw-rw---- 1 mysql mysql 6433 Sep 20 13:05 cacti.err
-rw-rw---- 1 root mysql 10485760 Sep 19 17:41 ibdata1
-rw-rw---- 1 root mysql 5242880 Sep 19 17:41 ib_logfile0
-rw-rw---- 1 root mysql 5242880 Sep 19 13:13 ib_logfile1
drwx------ 2 root mysql 4096 Sep 19 13:12 mysql
-rw-rw---- 1 root mysql 15117 Sep 19 13:12 mysql-bin.000001
-rw-rw---- 1 root mysql 484379 Sep 19 13:12 mysql-bin.000002
-rw-rw---- 1 root mysql 281933 Sep 19 16:52 mysql-bin.000003
-rw-rw---- 1 root mysql 117 Sep 19 16:52 mysql-bin.000004
-rw-rw---- 1 root root 117 Sep 19 17:19 mysql-bin.000005
-rw-rw---- 1 root root 484379 Sep 19 17:19 mysql-bin.000006
-rw-rw---- 1 root root 255 Sep 19 17:41 mysql-bin.000007
-rw-rw---- 1 root mysql 133 Sep 19 17:19 mysql-bin.index
drwx------ 2 root mysql 4096 Sep 19 13:12 test
于是，我再次查看/etc/init.d/mysqld这个启动文件查看启动这个文件的变量，完全没有差异，/etc/my.cnf也没有任何的错误配置。这里我想到了权限的设置(蓝色的提示)，这是想起权限出现了问题，mysqld无法读取改文件，做一下命令即可变更权限设置
[root@cacti mysql]# chown -R root .
[root@cacti mysql]# chgrp -R mysql .
[root@cacti mysql]# chown -R mysql var
[root@cacti mysql]# ll
total 80
drwxr-xr-x 2 root mysql 4096 Sep 19 17:19 bin
drwxr-xr-x 3 root mysql 4096 Sep 19 13:09 include
drwxr-xr-x 2 root mysql 4096 Sep 19 17:19 info
drwxr-xr-x 3 root mysql 4096 Sep 19 13:09 lib
drwxr-xr-x 2 root mysql 4096 Sep 19 17:19 libexec
drwxr-xr-x 3 root mysql 4096 Sep 19 13:10 man
drwxr-xr-x 7 root mysql 4096 Sep 19 17:19 mysql-test
drwxr-xr-x 3 root mysql 4096 Sep 19 13:10 share
drwxr-xr-x 5 root mysql 4096 Sep 19 17:19 sql-bench
drwx------ 5 mysql mysql 4096 Sep 20 13:12 var
变更完成后，启动成功，以下为提示信息，
[root@cacti var]# service mysqld start
Starting MySQL [ OK ]
总结：
遇到错误一定要看错误提示信息，从哪里我们可以找到原始的提示信息，可以给出我们提出相关的解决方案的思路！