Which component maintains all the UNIX directories?

An inode is the fundamental data structure in UNIX filesystems that maintains metadata about files and directories, including permissions, ownership, timestamps, and pointers to data blocks. Every file and directory in UNIX is represented by an inode. The Kernel uses inodes to manage the filesystem, init is a process manager, and fcntl is a file control function—none of these directly maintain directory structures.

Step-by-step Derivation:
In UNIX filesystems:

• Inode: A data structure containing metadata (permissions, owner, timestamps, block pointers) for each file/directory. Inodes are indexed and stored in the inode table.
• Kernel: Manages inode structures but does not 'maintain' them in the architectural sense.
• init: The first user-space process (PID 1) that manages other processes, not filesystem structures.
• fcntl: A system call for file descriptor control (locks, flags), not directory maintenance.
  The inode is the component that actually maintains directory information through its structure and the directory entries it points to.