P2 grading is done

Unions:
	Let's do an actual demo
		Poor unions always get swept under the rug

The nature of data:  Structures, strings, and arrays
	"pickle", or just write to disk
		padding can cause issues doing this directly
		Dynamic data structures may take some searching
		Memory addresses won't be ok if written/resurrected

File Systems, OS Perspective
	Unified file tree (independent of hardware)
	open file table
	Multiple users may open a file at once
	Open count and lsof
	Use count
	inode (index node?)
		- ls -i
		- ReiserFS omits inode table
		- struct inode
		- vnodes in BSD
	Links to inodes and stat
	Loops in linking and symbolic links vs. hard links
		- find with symbolic link loop
	Copy using hard link
	types and file
	"magic numbers" in files
	#!
	permissions and execution
	Mounting directories (sshfs, usb)
		- automount daemons
		- mounting in multiple places
	Multiple users and tail -f
	Unix permissions vs. ACL
	opening a file and file descriptors

OS structures:
	inode (index node)
	dentry (directory entry)
	superblock (describes a filesystem)
	file (file object, directories have one too)
	Each of this contains a _operations structure
	If these aren't on the disk, they must be generated
		- Some filesystems always generate all of them
		- dentry is typically generated
		- Reiserfs generates inodes
		- Non-unix filesystems generate them
		- You can just write a struct to disk

OO concepts:
	We don't have c++
		- No implicit this/self
	VFS is designed using an OO paradigm
	In some cases a default operation can be inherited

Operations for each of these
	
So could we just add operations, like lseek or whatever?
	Sure
	Let's add a secret command to some module we wrote