The TTY subsystem contains the TTY driver, line discipline(s) and hardware drivers (keyboard driver, display driver). Let's say I use a virtual terminal/console. So, my current session uses
/dev/tty1 (TTY device 1). When I press Ctrl+Alt+F2, I open another session which now uses
/dev/tty2 (TTY device 2).
So, who controls which
/dev/ttyN is the active one?
How about output from inactive
Input from process attached to it cannot be output to line discipline
because it is an inactive tty. So, input from process will just be dropped?