apache上php运行主要两种方式，一种是将php以apache的模块加载，另一种是运行单独的php-cgi进程，解析php。
php模块安装相应软件包即可，如debian下apt-get install libapache2-mod-php5。

fastcgi网上可以搜索到fastcgi和fcgid两个模块，较适合使用的为fcgid，在apache项目的页面上有单独的链接页面。debian下运行apt-get install libapache2-mod-fcgid。

下面是其他相关的配置，来自apache项目上的在线文档：
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# FcgidMaxRequestsPerProcess should be <= PHP_FCGI_MAX_REQUESTS
# The example PHP wrapper script overrides the default PHP setting.
FcgidMaxRequestsPerProcess 10000

# Uncomment the following line if cgi.fix_pathinfo is set to 1 in
# php.ini:
# FcgidFixPathinfo 1

Alias /phpapp/ /usr/local/phpapp/
<Location /phpapp/>
AddHandler fcgid-script .php
Options +ExecCGI
FcgidWrapper /usr/local/bin/php-wrapper .php

# Customize the next two directives for your requirements.
Order allow,deny
Allow from all
 </Location>
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新建的/usr/local/bin/php-wrapper
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PHP wrapper script - /usr/local/bin/php-wrapper #!/bin/sh
# Set desired PHP_FCGI_* environment variables.
# Example:
# PHP FastCGI processes exit after 500 requests by default.
PHP_FCGI_MAX_REQUESTS=10000
export PHP_FCGI_MAX_REQUESTS

# Replace with the path to your FastCGI-enabled PHP executable
exec /usr/local/bin/php-cgi
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