今天在測試環境把LAMP(Linxu+Apache+Mysql+PHP/Python/Perl)架構搭建起來以後，出現了兩個問題
1，php鏈接mysql出錯，結果是沒有加載對應的mysql模塊
2，創建了兩個虛擬機，訪問的時候卻始終只會訪問其中一個默認的(我看了下是按我配置文件名排序的第一個文件創建的虛擬機）
解決方法
1，在php的文件 /etc/php.ini 當中有個配置參數 extension_dir ，默認是註銷的，我看了下我本地對應的mysql模塊是存在，有 mysql.so 文件。
此時可以執行 php -m 去查看對應的模塊是否加載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]
這裏可以發現問題所在，所以修改extension_dir參數爲 “extension_dir = "/usr/lib64/php/modules/" ”
再次執行php -m 不會又任何warning信息，此時會正常顯示全部已經加載的模塊，
經過測試之後php鏈接mysql ok
2，兩個虛擬主機訪問都指向了同一個默認的主機，卻沒有報錯，後來httpd -S 去check看配置文件是否有錯，顯示
[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
雖然語法正確，但是有個warn顯示： _default_ VirtualHost overlap on port 80, the first has precedence
原來是我的主配置文件裏面的 #NameVirtualHost *:80 是註銷的，所以當第二個虛擬主機訪問的時候會訪問第一個默認的，
去掉這個參數前面的註銷符，然後重啓apache service之後在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]#
再次頁面訪問測試，一切OK