PHP allows you to set a variety of configuration settings in either the web server’s configuration (e.g. Apache’s httpd.conf or .htaccess) and using the ini_set function. The PHP manual contains a complete list of php.ini directives and this short post is simply my place of bookmarking the list, as I often need to refer to it.
The page in the manual lists all the configuration options, the default value, where it can be changed, and which version of PHP it is applicable from. The name of the option is also linked to the approprate section on a second page with more details describing it and its use.
For example, the allow_url_fopen setting allows file opening functions to open remote files via ftp or http when enabled. The default setting from the manual page is “1” (meaning it is enabled), and it can be changed anywhere for PHP versions <= 4.3.4 but only in the system configuration (httpd.conf or php.ini) for later versions.
The manual page is here: http://www.php.net/manual/en/ini.list.php