Permissions are inheritance, accumulation, priority, and cross.
The inheritance is to say that the lower level directory is set by the following directory. There is also a case where you want to explain that when copying your directory or file within a partition, copy past directory and file will have the previous directory permissions set now. However, when moving catalogs or files in partitions, moving past directorys and files will have its original permissions settings.
Accumulation is to say that there are two users in Group1, but they are "read" and "write" on a file or directory, then Group Group1 is accessible to the file or directory. The sum of the access rights for user1 and user2, is actually taken the biggest one, ie "read" "write" = "write". Another example is the user user1 belongs to group group1 and group2, and Group1 is "read-only" type for a file or directory, and Group2 is "fully controlled" type for this file or folder. , The user user1 is accumulated in two grouping rights for the file or folder, namely "read-only" "full control" = "complete control".
Priority, this feature of permissions includes two sub-characteristics, one is the permission of the document access rights priority, that is, the file permissions can be across the directory, regardless of the settings of the first level folder. Another feature is "reject" permission priority other permissions, that is, "reject" permissions can cross all other permissions, once the "Reject" permissions are selected, other permissions can not take any effect, which is equivalent to not set.
The crossability means that the same folder sets the shared permissions for a user and sets the folder for the user, and the principle of payment is inconsistent with the permissions, it is the intersection of two privileges. That is, the most stringent, minimal permissions. If the directory A is the shared permission set for the user USER1, "Read-only", and the directory A is "full control" set for the user USER1, and the final access to the user is "read-only".
