经常当php页面中利用include, require, require_once包含了一些其他位置的页面时，会出现错误，比如没有发现次页面，或者权限不允许等，可以根据以下方法来排除
1. 出现“未找到文件“类似的错误时候，检查include文件的位置是否正确，下面引用php手册页面的原话：
Files for including are first looked in include_path relative to the current working directory and then in the directory of the current script. E.g. if your include_path is libraries, current working directory is /www/, you included include/a.php and there is include "b.php" in that file, b.php is first looked in /www/libraries/ and then in /www/include/. If filename begins with ./ or ../, it is looked only in include_path relative to the current working directory.
2. 当出现permission deny 类似错误的时候，按以下方法排除
a) 检测被包含的文件读权限是否打开
b) 检测被包含的文件路径上的每个目录的x权限是否打开，该权限决定了目录能否被浏览。