DIRECTORY (V)                3/15/72                DIRECTORY (V)

NAME            format of directories

DESCRIPTION     A directory behaves exactly like an ordinary

                file, save that no user may write into a direc-

                tory.  The fact that a file is a directory is in-

                dicated by a bit in the flag word of its i-node


                Directory entries are 10 bytes long.  The first

                word is the i-number of the file represented by

                the entry, if non-zero; if zero, the entry is


                Bytes 2-9 represent the (8-character) file name,

                null padded on the right.  These bytes are not

                cleared for empty slots.

                By convention, the first two entries in each di-

                rectory are for "." and "..".  The first is an

                entry for the directory itself.  The second is

                for the parent directory.  The meaning of ".." is

                modified for the root directory of the master

                file system and for the root directories of re-

                movable file systems.  In the first case, there

                is no parent, and in the second, the system does

                not permit off-device references.  Therefore in

                both cases ".." has the same meaning as ".".

SEE ALSO        file system (V)