Question

centos6.5里面启动mysql出现PID文件加载失败问题，请问要怎么解决呀？

就是在centos里面安装mysql的时候初始化就报错了，我在网上油进行相关的搜索，但是没有找到对应我这个问题的，求问！谢谢大佬们！

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Answer 1

1. /etc/my.cnf的默认配置
配置文件的内容如下：
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Default to using old password format for compatibility with mysql 3.x
# clients (those using the mysqlclient10 compatibility package).
old_passwords=1
[mysql.server]
user=mysql
basedir=/var/lib
[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
由于项目需要需要修改datadir的值，如下
datadir=/usr/local/project/etc/data
在CentOS中启动MySQL：
[wzhwho@local~]#service mysqld start
Starting mysqld daemon [FAILED]
2. 先看错误日志
采用rpm安装的MySQL日志文件的默认路径是/var/log/mysqld.log
mysqld started
InnoDB: Operating system error number 13 in a file operation.
InnoDB: The error means mysqld does not have the access rights to
InnoDB: the directory.
InnoDB: File name /usr/local/project/etc/data/ibdata1
InnoDB: File operation call: 'create'.
InnoDB: Cannot continue operation.
mysqld ended
从日志可以知道，mysql的数据文件目录没有权限，所以我需要按照/var/lib/mysql目录的权限给/usr/local/project/etc/data目录设置权限和属主。
[wzhwho@local~]#ll /var/lib
drwxr-x-r-x 1 mysql mysql 4 Apr 11 2009 mysql
[wzhwho@local~]#ll /var/lib
[wzhwho@local~]chown -R mysql:mysql /usr/local/project/etc/data
[wzhwho@local~]chmod -R 755 /usr/local/project/etc/data
[wzhwho@local~]#ll /usr/local/project/etc
drwxr-x-r-x 1 mysql mysql 4 Apr 11 2009 data
接着我又启动了MySQL，但是还是失败，日志信息还是一样。
3. 修改配置文件/etc/selinux/config
最后，我在外国友人的邮件来往中查到这样的回复：
If you are using SE linux, set it to permissive mode by editing /etc/selinux/config
and changing
SELINUX=enforcing to SELINUX=permissive
This solved all of my problems with the
"Operating system error number 13 in a file operation" error
所以，最后确定为selinux的问题，输入命令ls -Z，你会发现在文件或文件夹上面打的标签。如果一个文件是在selinux打开的时候创建的，那么即使你关闭selinux，它的权限控制还是会起作用的。可以通过chcon来改变权限。
4. MySQL成功启动
[wzhwho@local~]#service mysqld start
Starting mysqld daemon [OK]