[NTLUG:Discuss] inodes

[Leroy Tennison]

Another interview question dealt with what inodes contain.  Google is 
leading to confusion.  I suspect the reason is inadequate qualification 
of statements but I'd rather find out than be mis-informed.  Statements 
I'm finding:

There is no difference between a file and a directory since the latter 
is just a special type of file. 

Some references say that inodes describe files 
(www.cse.psu.edu/~anand/spring01/linux/files.ppt  - slide 2 and 
http://www.freeos.com/articles/3851/) while one reference 
(http://www-rohan.sdsu.edu/doc/debian/ch-advanced.html) says that the 
inode contains the file.

A hard link is a pointer to an inode.

A directory is simply a list of filename and inode pairs.

You can not have a hard link to a directory in most UNIXes.

Questions:

If a directory is a file and files are accessed through inodes and users 
access inodes through hard links then how does a  user access a 
directory if it doesn't have a hard link in another directory?  Should 
the statement about most UNIXes not allowing hard links to directories 
really say that they don't allow more than one hard link to a directory 
or is there some other answer?

Is the most accurate description of an inode that it contains both 
information about a file (or directory) such as ownership and 
permissions as well as  pointers to it's data blocks and, as a result, 
is the only mechanism for accessing those data blocks as a file?  (I'm 
excluding the concept of accessing the data blocks as raw storage by 
lower-level functions doing disk maintenance).


Thanks for helping me understand.