11/3/71                                             DIRECTORY (V)

NAME            format of directories

SYNOPSIS        --

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-node of the file represented by the

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

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

                null padded on the right.  These bytes are not

                necessarily 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 without a mount

                system call.  Therefore in both cases ".." has

                the same meaning as ".".

FILES           --

SEE ALSO        file system format


BUGS            --

OWNER           ken, dmr