So far, we've been looking at permissions from the perspective of regular files. When it comes to directories, things are a bit different. Directories use the same permissions flags, but they are interpreted to mean slightly different things.

For a directory, if the 'read' flag is set, you may list the contents of the directory; 'write' means you may create files in the directory, and 'execute' means you may enter the directory and access any sub-directories inside. Without the 'execute' flag, the filesystem objects inside a directory aren't accessible. Without a 'read' flag, the filesystem objects inside a directory aren't viewable, but objects inside the directory can still be accessed as long as someone knows the full path to the object on disk.