Why not just not support hard links?

Posted Sep 3, 2004 16:41 UTC (Fri) by giraffedata (guest, #1954)
In reply to: Why not just not support hard links? by walles
Parent article: More notes on reiser4

He's using a rather expansive definition of "hard link." Usually, "hard link" refers only to a reference to a file from a directory entry. The kind of reference you get when you open a file isn't called a hard link. (It's just called a reference).

Incidentally, most of this thread is using "hard link" in a too restrictive way. When you create a file 'foo', you create one hard link to the file (from the directory entry with name 'foo'). When you ln foo bar, you create a second hard link to the file. Note that Unix files themselves do not have names -- not text ones anyway; they are traditionally named by inode number.

Directories have lots of hard links. There's the one from the parent directory, the one from '.', and all the ones from the subdirectories' '..' entries. In some modern models, '.' and '..' aren't actually considered directory entries, but you'll still see them -- for historical purposes -- in the directory's link count (e.g. from ls -l).

But you can't make an arbitrary hard link to a directory. Only the specific ones described above are allowed to exist.