今天在测试环境把LAMP(Linxu+Apache+Mysql+PHP/Python/Perl)架构搭建起来以后，出现了两个问题
1，php链接mysql出错，结果是没有加载对应的mysql模块
2，创建了两个虚拟机，访问的时候却始终只会访问其中一个默认的(我看了下是按我配置文件名排序的第一个文件创建的虚拟机）
解决方法
1，在php的文件 /etc/php.ini 当中有个配置参数 extension_dir ，默认是注销的，我看了下我本地对应的mysql模块是存在，有 mysql.so 文件。
此时可以执行 php -m 去查看对应的模块是否加载ok了，
[root@colinspace etc]# php -m
PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php/modules/mysql.so' - /usr/lib/php/modules/mysql.so: cannot open shared object file: No such file or directory in Unknown on line 0
PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php/modules/mysqli.so' - /usr/lib/php/modules/mysqli.so: cannot open shared object file: No such file or directory in Unknown on line 0
PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php/modules/pdo.so' - /usr/lib/php/modules/pdo.so: cannot open shared object file: No such file or directory in Unknown on line 0
PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php/modules/pdo_mysql.so' - /usr/lib/php/modules/pdo_mysql.so: cannot open shared object file: No such file or directory in Unknown on line 0
PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php/modules/pdo_sqlite.so' - /usr/lib/php/modules/pdo_sqlite.so: cannot open shared object file: No such file or directory in Unknown on line 0
[PHP Modules]
bz2
calendar
Core
ctype
date
ereg
exif
filter
ftp
gettext
gmp
hash
iconv
libxml
openssl
pcntl
pcre
readline
Reflection
session
shmop
SimpleXML
sockets
SPL
standard
tokenizer
xml
zlib
[Zend Modules]
这里可以发现问题所在，所以修改extension_dir参数为 “extension_dir = "/usr/lib64/php/modules/" ”
再次执行php -m 不会又任何warning信息，此时会正常显示全部已经加载的模块，
经过测试之后php链接mysql ok
2，两个虚拟主机访问都指向了同一个默认的主机，却没有报错，后来httpd -S 去check看配置文件是否有错，显示
[root@colinspace etc]# httpd -S
httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1 for ServerName
[Sat Mar 08 20:08:14 2014] [warn] _default_ VirtualHost overlap on port 80, the first has precedence
VirtualHost configuration:
wildcard NameVirtualHosts and _default_ servers:
*:80 bbs.example.com (/etc/httpd/conf.d/bbs.conf:1)
*:80 blog.example.com (/etc/httpd/conf.d/blog.conf:1)
Syntax OK
虽然语法正确，但是有个warn显示： _default_ VirtualHost overlap on port 80, the first has precedence
原来是我的主配置文件里面的 #NameVirtualHost *:80 是注销的，所以当第二个虚拟主机访问的时候会访问第一个默认的，
去掉这个参数前面的注销符，然后重启apache service之后在check，就ok了
[root@colinspace etc]# /etc/init.d/httpd restart
Stopping httpd: [ OK ]
Starting httpd: httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1 for ServerName
[ OK ]
[root@colinspace etc]# httpd -S
httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1 for ServerName
VirtualHost configuration:
wildcard NameVirtualHosts and _default_ servers:
*:80 is a NameVirtualHost
default server bbs.example.com (/etc/httpd/conf.d/bbs.conf:1)
port 80 namevhost bbs.example.com (/etc/httpd/conf.d/bbs.conf:1)
port 80 namevhost blog.example.com (/etc/httpd/conf.d/blog.conf:1)
Syntax OK
[root@colinspace etc]#
再次页面访问测试，一切OK