file_descriptor_in_unix.txt

	What is a file descriptor in unix?

	real files
	directories
	symbolic links

	devices drivers (c,b,u,p)

	named/unnamed pipe
	named/unnamed unix socket

	tcp listening sockets
	tcp connections
	netlink sockets

	weird stuff:
	============
	signal file descriptors
	event file descriptors
	timer file descriptors
	inotify (directory or file watch) file descriptors.
	virtual files (tell you about the OS, processes, modules or other things).
	pts's (pseudo terminals)