The difference between /proc and /sys
The difference between procfs and sysfs
/dev, /proc, /sys
wikipedia: Device file
wikipedia: procfs
wikipedia: tmpfs
wikipedia: sysfs

What are those /dev/ Files?
What are those /dev/ Files?

A device file or special file is an interface for a device driver that appears in a file system as if it were an ordinary file, it allow software to interact with a device driver using standard input/output system calls, which simplifies many tasks and unifies user-space I/O mechanisms.

tty, pty, pts, ptmx, console, xconsole
man 4 pts
wikipedia: devpts
Pseudoterminal
tty/pty/pts/ptmx详解
Linux Containers, /dev/pts/ptmx, and Gentoo

ls –ignore={sda,tty,vbox,vcs,loop}*