PHP safe_mode is not present on PHP 5.4 and later versions. Although it offers valuable protection to users of earlier versions, it is annoying to work with. If you don't want to deal with it, update to a supported version of PHP.
We used to offer a way to disable safe_mode in earlier versions called PHP Flex, but this was an inferior CGI-based mechanism that is very slow compared to the other alternatives. The new PHP 5.4+ mechanism offers all the features and security of PHP Flex, uses compatible paths, and is much faster. Seriously, don't use PHP Flex. If you're following a HOWTO online that refers to PHP Flex, use PHP instead and please advise the author to update their document.