An important aspect of computer security involves granting and denying permissions. A permission is the ability to perform a specific operation, such as gaining access to data or executing code. Permissions are granted at the level of folders, files, or apps. Use the Server app to set up File Sharing service permissions.
The term privileges refers to the combination of ownership and permissions, whereas the term permissions refers to the permission settings that each user category can have (Read & Write, Read Only, Write Only, and None).
If you’re new to OS X and aren’t familiar with UNIX-based operating systems, there are differences in the way ownership and permissions are handled compared to Windows.
To increase security and reliability, OS X sets many system folders (for example, /Library/) to be owned by the root user (literally, a user named root). You can only change or delete files and folders if you authenticate as an administrator.
Note: The Finder calls the root user system.
By default, files and folders are owned by the user who creates them. After they’re created, items keep their privileges (a combination of ownership and permissions) even when moved, unless the privileges are explicitly changed by their owner or an administrator.
WARNING: There are few restrictions on what you can do when you log in as root, and changes to system data can cause problems. An alternative to logging in as root is to use the sudo command.
Therefore, new files and folders you create aren’t accessible by users if they’re created in a folder that users don’t have privileges for. When setting up share points, make sure that items have the correct access privileges for the users you want to share them with.