Maurice Bach, "The Design of the UNIX Operating System", on page 73 describes the format of directory entries: https://archive.org/details/DesignOfTheUnixOperat

Maurice Bach, "The Design of the UNIX Operating System", on page 73 describes the format of directory entries: https://archive.org/details/DesignOfTheUnixOperatingSystemByMauriceBach/page/n85 https://archive.org/details/DesignOfTheUnixOperatingSystemBy... "Directory entries may be empty, indicated by an inode number of 0". So if the pseudo-code is correct, this may be an utility to squeeze out those empty entries.