Daniel Harris says, root-owned configuration files often need to be edited by those without root privileges; instead of using programs like sudo or calife and risking shell escapes in editors, it would be better just to allow certain non-owners to edit these files. Access Control Lists (ACLs) solve these problems. They allow more flexibility than the standard Unix user/group/other set of permissions. ACLs have been available in commercial UNIXes such as IRIX, Solaris and in Windows NT for years. Read more.