Today I learned that PHP’s mkdir() with the octal permission argument apparently doesn’t support any value other than 0 in the leftmost octal spot (where setuid, setgid, and sticky bit go). If you try something like 2755 or '2755', it will interpret it as or typecast it to an integer, and your permissions will end up very different than what you want. An octal in PHP is just a special language format to define a regular integer, where you put a 0 at the beginning of a number. So 02755 is the PHP octal to match octal 2755. This sets the 755 correctly, but it still doesn’t handle the 2 spot at all. I’m not sure why. I guess that has to be done after the fact.