PHP regex problem

PHP allows the use of the PCRE library, but PHP5 comes with an interesting, undocumented twitch: You have to add -with-pcre-regex if you want to use preg_match(), a quite commonly used function. With PHP4, all you did was -with-pcre and you got the whole package, and the -with-pcre-regex is undocumented in the configure program of PHP5 which is where people look for this.