chmod - change the permissions mode of a file
        (4 read, 2 write, 1 execute) example:

        drwxr-x--x ericfitz example.file date time
         ^^^^^^^^^
          |  | _|_executable by others
          |  |
          | ---readable and executable by group
          |
          >owner has permission for all

        chmod 751 example.file - would give us these permissions