What is an inode, what it stores, how directories map names to inodes, hard link creation and deletion, link count.

What symlinks are, how they differ from hard links, dangling links, symlink chains, which syscalls follow them.

Creating hard links with link(), removing them with unlink(), when files are truly deleted, the anonymous temp file trick.

Renaming and moving files, creating directories, removing directories, atomic file updates with rename().

opendir(), readdir(), closedir(), rewinddir(), struct dirent, d_type, fdopendir(), readdir_r().

Recursively walking a directory tree, preorder vs postorder, flags, recursive deletion, find-like searches.

getcwd(), chdir(), fchdir() for save/restore, openat() for thread-safe file ops, chroot() jails.

Creating symlinks, reading symlink contents, resolving canonical paths, splitting pathnames into parts.