In this section, we'll take a look at the Linux permissions and ownership model. We've already seen that every file is owned by one user and one group. This is the very core of the permissions model in Linux. You can view the user and group of a file in a ls -l listing:

$ ls -l /bin/bash
-rwxr-xr-x    1 root     wheel      430540 Dec 23 18:27 /bin/bash

In this particular example, the /bin/bash executable is owned by root and is in the wheel group. The Linux permissions model works by allowing three independent levels of permission to be set for each filesystem object -- those for the file's owner, the file's group, and for all other users.