linux下Mysql启动问题及Linux下安装mysql-python并使用mysql和ssh无法使用

启动MySQL折腾近一下午

1、开始

[root@letfly ~]# service mysqld start
Redirecting to /bin/systemctl start  mysqld.service

Job failed. See system logs and 'systemctl status' for details.

[root@letfly ~]# cd /var/log/

[root@letfly log]# more mysqld.log
140812 16:11:56 mysqld_safe Starting mysqld daemon with databases from /var/li
b/mysql
140812 16:11:56 [Note] Plugin 'FEDERATED' is disabled.
140812 16:11:56 InnoDB: The InnoDB memory heap is disabled
140812 16:11:56 InnoDB: Mutexes and rw_locks use GCC atomic builtins
140812 16:11:56 InnoDB: Compressed tables use zlib 1.2.5
140812 16:11:56 InnoDB: Using Linux native AIO
140812 16:11:56 InnoDB: Initializing buffer pool, size = 128.0M
140812 16:11:56 InnoDB: Completed initialization of buffer pool
140812 16:11:56 InnoDB: highest supported file format is Barracuda.
140812 16:11:56  InnoDB: Waiting for the background threads to start
140812 16:11:57 [ERROR] Do you already have another mysqld server running on port: 3306 ?

查看3306端口

[root@letfly ~]# netstat -tunlp | grep :3306

没结果

折腾了一段时间，果断yum remove mysql

2、接着

[root@letfly ~]# yum install mysql

[root@letfly ~]# yum install mysql-devel

[root@letfly ~]# yum install mysql-server

接着启动MySQL：

[root@letfly ~]# clear
[root@letfly ~]# service mysqld start
Redirecting to /bin/systemctl start  mysqld.service
Job failed. See system logs and 'systemctl status' for details.

仍不行，查看日志，如下：

[root@letfly ~]# cd /var/log/
[root@letfly log]# more mysqld.log
140812 16:11:56 mysqld_safe Starting mysqld daemon with databases from /var/li
b/mysql
140812 16:11:56 [Note] Plugin 'FEDERATED' is disabled.
140812 16:11:56 InnoDB: The InnoDB memory heap is disabled
140812 16:11:56 InnoDB: Mutexes and rw_locks use GCC atomic builtins
140812 16:11:56 InnoDB: Compressed tables use zlib 1.2.5
140812 16:11:56 InnoDB: Using Linux native AIO
140812 16:11:56 InnoDB: Initializing buffer pool, size = 128.0M
140812 16:11:56 InnoDB: Completed initialization of buffer pool
140812 16:11:56 InnoDB: highest supported file format is Barracuda.
140812 16:11:56  InnoDB: Waiting for the background threads to start
140812 16:11:57 InnoDB: 1.1.8 started; log sequence number 1595675
140812 16:11:57 [Note] Server hostname (bind-address): '0.0.0.0'; port: 3306
140812 16:11:57 [Note]   - '0.0.0.0' resolves to '0.0.0.0';
140812 16:11:57 [Note] Server socket created on IP: '0.0.0.0'.
140812 16:11:57 [ERROR] Can't start server : Bind on unix socket: No such file
 or directory
140812 16:11:57 [ERROR] Do you already have another mysqld server running on s
ocket: /opt/lampp/var/mysql/mysql.sock ?

原来是socket问题

[root@letfly mysql]# find / -name 'my.cnf'
/etc/my.cnf

修改my.cnf里的

datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock（你先有的mysql位置）

[root@letfly mysql]# service mysqld start
Redirecting to /bin/systemctl start  mysqld.service

OK！！欧耶！！

mysql-python是一个用来在python中访问mysql数据库的类库，django中默认也是用这个类库来访问mysql。

一.下载

wget http://downloads.sourceforge.net/project/mysql-python/mysql-python-test/1.2.4b4/MySQL-python-1.2.4b4.tar.gz?use_mirror=ncu

二.修改site.cfg文件

修改site.cfg文件夹主要是告诉myslq-python的模块，mysql_config文件的路径，注意不是my.cnf文件。

将文件中下面这行配置的注释去掉，将“/usr/local/bin/mysql_config”改为你系统中mysql_conf文件所在路径。

#mysql_config = /usr/local/bin/mysql_config

三.安装

tar zxvf MySQL-python-1.2.4b4.tar.gz cd MySQL-python-1.2.4b4 python setup.py install

四.连接mysql

如没安装mysql

yum install mysql

测试非常简单，检查MySQLdb 模块是否可以正常导入。

[root@letfly opt]# ipython
Python 2.7.3 (default, Jul 24 2012, 11:41:34) 
Type "copyright", "credits" or "license" for more information.

IPython 0.12 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object', use 'object??' for extra details.

In [1]: import MySQLdb

常见问题：

1.Python版本不对

如果系统中有多个版本的python话，建议将django和mysql-python安装到高版本的python中。方法是安装时将python换为pythonxx，比如python2.7.3，安装命令就是：

python27 setup.py install

2.找不到libmysqlclient

开始使用mysql-python可能都会遇到错误提示如下

django.core.exceptions.ImproperlyConfigured: Error loading MySQLdb module: libmysqlclient_r.so.16: cannot open shared object file: No such file or directory

解决方法是：将“mysql安装目录/lib/mysql”目录下的libmysqlclient_r.so.16拷贝一份到“/usr/lib”目录。

1）问题：ImportError: libmysqlclient_r.so.16: cannot open shared object file: No such file or directory
原因是python无法找到mysql目录下的libmysqlclient_r.so.16动态库,其实MySQLdb是调用mysql的c函数库.所以本机上首先得安装了mysql
然后: export LD_LIBRARY_PATH=/usr/local/mysql/lib/mysql:$LD_LIBRARY_PATH
并且将/usr/local/mysql5.1/lib/mysql 放入/etc/ld.so.conf中
/etc/ld.so.conf改后内容为：
include ld.so.conf.d/*.conf
/usr/local/mysql5.1/lib/mysql

3._mysql.c:29:20: 致命错误：Python.h：没有那个文件或目录

yum install python-devel mysql-devel

最后重新再测试一下，就不会有上面的问题了