Editing Inode (section)

===Historical possibility of directory hard linking===

Historically, it was possible to [[hard link]] directories. This made the directory structure an arbitrary [[directed graph]] contrary to a [[directed acyclic graph]]. It was even possible for a directory to be its own parent. Modern systems generally prohibit this confusing state, except that the parent of ''root'' is still defined as root. The most notable exception to this prohibition is found in [[macOS|Mac OS X]] (versions 10.5 and higher) which allows hard links of directories to be created on [[HFS+]] file systems by the superuser.<ref>{{cite web | url = https://stackoverflow.com/questions/80875/what-is-the-unix-command-to-create-a-hardlink-to-a-directory-in-os-x|title=What is the Unix command to create a hardlink to a directory in OS X?|website=[[Stack Overflow]]|date=16 Jan 2011|access-date=5 Jan 2020|archive-url= https://web.archive.org/web/20200105174407/https://stackoverflow.com/questions/80875/what-is-the-unix-command-to-create-a-hardlink-to-a-directory-in-os-x|archive-date=5 January 2020|url-status=live}}</ref>