Berkeley Unix networking device which appears to an

application program as an ordinary terminal but which is in

fact connected via the network to a process running on a

different host or a windowing system. Pseudo-ttys have a

slave half and a control half. The slave tty (/dev/ttyp*) is

the device that user programs use and the control tty

(/dev/ptyp*) is used by daemons to talk to the net.