The normal Linux file and directory permissions settings are okay, but they're not very granular. With an ACL, we can allow only a certain person to access a file or directory, or we can allow multiple people to access a file or directory with different permissions for each person. If we have a file or a directory that's wide open for everyone, we can use an ACL to allow different levels of access for either a group or an individual. Towards the end of the chapter, we'll put what we've learned all together in order to manage a shared directory for a group.

You would use getfacl to view an access control list for a file or directory. (Note that you can't use it to view all files in a directory at once.) To begin, let's use getfacl to see if we have any access control lists already set on...