须有配置好的环境 详情见：centos6.5下yum安装lnmp(适合刚入职的新手的方法) http://www.cnblogs.com/qzjpkfj/p/4211126.html
具体安装步骤详情见：
转载自：Linux下安装php开发框架yaf http://www.linuxde.net/2013/07/14805.html
1.下载并安装yaf扩展http://pecl.php.net/package/yaf
#wget http://pecl.php.net/get/yaf-2.2.9.tgz
#tar zxvf yaf-2.2.9.tgz
#cd yaf-2.2.9 [root@bogon yaf-2.2.9]# whereis phpize
phpize: /usr/bin/phpize /usr/share/man/man1/phpize.1.gz (有可能 whereis phpize 运行的是空的，我配置就是；是因为phpize没安；一条命令安装：yum install php-devel)
/usr/bin/phpize [root@bogon yaf-2.2.9]# /usr/bin/phpize
Configuring for:
PHP Api Version: 20090626
Zend Module Api No: 20090626
Zend Extension Api No: 220090626
#whereis php-config
php-config: /usr/bin/php-config /usr/share/man/man1/php-config.1.gz #./configure --with-php-config=/usr/bin/php-config （如果提示错误：configure: error: in `/root/yaf-2.2.9':configure: error: no acceptable C compiler found in $PATHSee `config.log' for more details. 说明没安装gcc 一条命令安装 yum -y install gcc）
#make && make install
（make && make install 如果执行出错如下）
In file included from /root/yaf-2.1.2/yaf_router.c:28:
/usr/include/php/ext/pcre/php_pcre.h:29:18: error: pcre.h: No such file or directory
In file included from /root/yaf-2.1.2/yaf_router.c:28:
/usr/include/php/ext/pcre/php_pcre.h:45: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token
/usr/include/php/ext/pcre/php_pcre.h:46: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token
/usr/include/php/ext/pcre/php_pcre.h:52: error: expected specifier-qualifier-list before ‘pcre’
make: *** [yaf_router.lo] 错误 1
解决办法
# yum install pcre-devel 安装 pcre-devel即可解决了。
2.添加扩展配置到PHP.ini
在/etc/php.ini文件里添加一行
extension=yaf.so
重启webserver 即可。