I’m new to Linux-like operating systems, and I’ve come across an issue where when a program tries to create a file or directory, it doesn’t have the proper permissions. Specifically, PHP running as the user www-data cannot access or create files or directories when the working directory is owned by the root user. I tried changing individual file permissions with chmod but that did not work; I was successful with using chown to allow PHP to create a file in a directory it owned, but now I as a root user cannot access any of the files it creates without moving them to a directory owned by root (even though the PHP-owned directory is still owned by the root group). Is there a way to give multiple users ownership of a directory? Thanks!