pear是PHP的扩展和应用程序库，包含了很多有用的类，安装好php5.0后，pear实际上并没有被安装，可以执行一下命令来安装
pear sudo cp /private/etc/php.ini.default /private/etc/php.ini sudo php /usr/lib/php/install-pear-nozlib.phar pear config-set php_ini /private/etc/php.ini pecl config-set php_ini /private/etc/php.ini sudo pear upgrade-all
如果执行第二个语句的时候，遇到以下类似的提示信息，说明你的~/ 下面已经存在.pearrc文件了，可以先删除.pearrc然后在执行就可以了 [PEAR] Archive_Tar: upgrade to a newer version (1.3.7 is not newer than 1.3.7) [PEAR] Console_Getopt: upgrade to a newer version (1.3.0 is not newer than 1.3.0) [PEAR] Structures_Graph: upgrade to a newer version (1.0.4 is not newer than 1.0.4) [PEAR] XML_Util: upgrade to a newer version (1.2.1 is not newer than 1.2.1) [PEAR] PEAR: upgrade to a newer version (1.9.4 is not newer than 1.9.4)
