Managing User Permissions on Unix

I am basically posting this here as a reference for myself, but I’m sure the information will be helpful to other people out there, as well.

Occasionally, when working on my Web server, I need to create a new user on the server and grant one or more other users permission to view and edit files within the new user’s home directory. This task, in itself, does not seem all that difficult on the surface. However, because most Unix servers are set up (and rightfully so, for security purposes) not to allow most users to navigate outside of their own home directories, it becomes a problem.

Let’s say, for example, that you have two users on your Web server that you want to allow permissions to view and edit each other’s home directories, but you don’t want them to have access to any other files and folders on the Web server.